Service manual | American Standard 6065161.002 Indoor Furnishings User Manual

SERVICE MANUAL
COMMAND CV17-750
VERTICAL CRANKSHAFT
Contents
Section 1. Safety and General Information ............................................................................
Section 2. Tools & Aids ..........................................................................................................
Section 3. Troubleshooting .....................................................................................................
Section 4. Air Cleaner and Air Intake System ........................................................................
Section 5. Fuel System and Governor ....................................................................................
Section 5B. Electronic Fuel Injection (EFI) Fuel System ......................................................
Section 6. Lubrication System ................................................................................................
Section 7. Retractable Starter .................................................................................................
Section 8. Electrical System and Components .....................................................................
Section 9. Disassembly ...........................................................................................................
Section 10. Inspection and Reconditioning ...........................................................................
Section 11. Reassembly ...........................................................................................................
1
2
3
4
5
5B
6
7
8
9
10
11
Section 1
Safety and General Information
1
Section 1
Safety and General Information
Safety Precautions
To ensure safe operation please read the following statements and understand their meaning. Also
refer to your equipment manufacturer's manual for other important safety information. This manual
contains safety precautions which are explained below. Please read carefully.
WARNING
Warning is used to indicate the presence of a hazard that can cause severe personal injury, death,
or substantial property damage if the warning is ignored.
CAUTION
Caution is used to indicate the presence of a hazard that will or can cause minor personal injury or
property damage if the caution is ignored.
NOTE
Note is used to notify people of installation, operation, or maintenance information that is important
but not hazard-related.
For Your Safety!
These precautions should be followed at all times. Failure to follow these precautions could result in injury to yourself
and others.
WARNING
WARNING
Accidental Starts can cause
severe injury or death.
Rotating Parts can cause severe
injury.
Disconnect and ground spark plug
leads before servicing.
Stay away while engine is in
operation.
Accidental Starts!
Disabling engine. Accidental starting
can cause severe injury or death.
Before working on the engine or
equipment, disable the engine as follows:
1) Disconnect the spark plug lead(s). 2)
Disconnect negative (-) battery cable
from battery.
Rotating Parts!
Keep hands, feet, hair, and clothing away
from all moving parts to prevent injury.
Never operate the engine with covers,
shrouds, or guards removed.
WARNING
Hot Parts can cause severe burns.
Do not touch engine while operating
or just after stopping.
Hot Parts!
Engine components can get extremely
hot from operation. To prevent severe
burns, do not touch these areas while the
engine is running—or immediately after
it is turned off. Never operate the engine
with heat shields or guards removed.
1.1
Section 1
Safety and General Information
WARNING
WARNING
Explosive Fuel can cause fires
and severe burns.
Carbon Monoxide can cause severe
nausea, fainting or death.
Do not fill the fuel tank while the
engine is hot or running.
Avoid inhaling exhaust fumes, and
never run the engine in a closed
building or confined area.
Explosive Fuel!
Gasoline is extremely flammable and its
vapors can explode if ignited. Store
gasoline only in approved containers, in
well ventilated, unoccupied buildings,
away from sparks or flames. Do not fill
the fuel tank while the engine is hot or
running, since spilled fuel could ignite if
it comes in contact with hot parts or
sparks from ignition. Do not start the
engine near spilled fuel. Never use
gasoline as a cleaning agent.
WARNING
Lethal Exhaust Gases!
Engine exhaust gases contain poisonous
carbon monoxide. Carbon monoxide is
odorless, colorless, and can cause death if
inhaled. Avoid inhaling exhaust fumes,
and never run the engine in a closed
building or confined area.
WARNING
Uncoiling Spring can cause severe
injury.
Wear safety goggles or face
protection when servicing
retractable starter.
Cleaning Solvents can cause severe
injury or death.
Use only in well ventilated areas
away from ignition sources.
Flammable Solvents!
Carburetor cleaners and solvents are
extremely flammable. Keep sparks,
flames, and other sources of ignition
away from the area. Follow the cleaner
manufacturer’s warnings and
instructions on its proper and safe use.
Never use gasoline as a cleaning agent.
1.2
Spring Under Tension!
Retractable starters contain a powerful,
recoil spring that is under tension.
Always wear safety goggles when
servicing retractable starters and
carefully follow instructions in
"Retractable Starter" Section 7 for
relieving spring tension.
WARNING
Explosive Gas can cause fires and
severe acid burns.
Charge battery only in a well
ventilated area. Keep sources of
ignition away.
Explosive Gas!
Batteries produce explosive hydrogen gas
while being charged. To prevent a fire or
explosion, charge batteries only in well
ventilated areas. Keep sparks, open
flames, and other sources of ignition
away from the battery at all times. Keep
batteries out of the reach of children.
Remove all jewelry when servicing
batteries.
Before disconnecting the negative
(-) ground cable, make sure all switches
are OFF. If ON, a spark will occur at the
ground cable terminal which could cause
an explosion if hydrogen gas or gasoline
vapors are present.
CAUTION
Electrical Shock can cause injury.
Do not touch wires while engine is
running.
Electrical Shock!
Never touch electrical wires or
components while the engine is running.
They can be sources of electrical shock.
Section 1
Safety and General Information
Engine Identification Numbers
When ordering parts, or in any communication
involving an engine, always give the Model,
Specification and Serial Numbers, including letter
suffixes if there are any.
1
Identification
Decal
The engine identification numbers appear on a decal,
or decals, affixed to the engine shrouding. See Figure
1-1. An explanation of these numbers is shown in
Figure 1-2.
Figure 1-1. Engine Identification Decal Location.
A. Model No.
C V 18 S
Command Engine
Version Code
S = Electric Start
Vertical Crankshaft
or
Horsepower
17 = 17 HP
18 = 18 HP
20 = 20 HP
22 = 22 HP
23 = 23 HP
25 = 25 HP
26 = 26 HP
C. Serial No.
or
61500
B. Spec. No.
Engine Model Code
Code
Model
72
CV17
61
CV18
65
CV20
67
CV22
69
CV25
75
CV22/23
79
CV26
Numerical Designation
730
740
745
750
Variation of
Basic Engine
(624 cc)
CV730-0001
CV740-0001
CV745-0001
CV750-0001
Complete Spec Number
(Incorporating Model No.
with Variation No. of
Basic Spec.)
(674 cc)
3305810334
Year Manufactured Code
Factory Code
Code
Year
Code
Year
30
2000
21
1991
31
2001
22
1992
32
2002
23
1993
33
2003
24
1994
34
2004
25
1995
35
2005
26
1996
36
2006
27
1997
37
2007
28
1998
29
1999
Figure 1-2. Explanation of Engine Identification Numbers.
1.3
Section 1
Safety and General Information
Oil Recommendations
Using the proper type and weight of oil in the
crankcase is extremely important. So is checking oil
daily and changing oil regularly. Failure to use the
correct oil, or using dirty oil, causes premature engine
wear and failure.
Oil Type
Use high-quality detergent oil of API (American
Petroleum Institute) Service Class SG, SH, SJ or
higher. Select the viscosity based on the air
temperature at the time of operation as shown in the
following table.
**
*
*Use of synthetic oil having 5W-20 or 5W-30 rating is
acceptable, up to 40°F.
**Synthetic oils will provide better starting in extreme
cold (below -10°F).
NOTE: Using other than service class SG, SH, SJ or
higher oil or extending oil change intervals
longer than recommended can cause engine
damage.
NOTE: Synthetic oils meeting the listed
classifications may be used with oil changes
performed at the recommended intervals.
However, to allow piston rings to properly
seat, a new or rebuilt engine should be
operated for at least 50 hours using standard
petroleum based oil before switching to
synthetic oil.
A logo or symbol on oil containers identifies the API
service class and SAE viscosity grade. See Figure 1-3.
Figure 1-3. Oil Container Logo.
1.4
Refer to Section 6 - “Lubrication System” for detailed
procedures on checking the oil, changing the oil and
changing the oil filter.
Fuel Recommendations
WARNING: Explosive Fuel!
Gasoline is extremely flammable and its vapors can explode if
ignited. Before servicing the fuel system, make sure there are no
sparks, open flames or other sources of ignition nearby as these
can ignite gasoline vapors. Disconnect and ground the spark
plug leads to prevent the possibility of sparks from the ignition
system.
General Recommendations
Purchase gasoline in small quantities and store in clean,
approved containers. A container with a capacity of 2
gallons or less with a pouring spout is recommended.
Such a container is easier to handle and helps eliminate
spillage during refueling.
Do not use gasoline left over from the previous season,
to minimize gum deposits in your fuel system and to
ensure easy starting.
Do not add oil to the gasoline.
Do not overfill the fuel tank. Leave room for the fuel to
expand.
Fuel Type
For best results, use only clean, fresh, unleaded gasoline
with a pump sticker octane rating of 87 or higher. In
countries using the Research method, it should be 90
octane minimum.
Unleaded gasoline is recommended as it leaves less
combustion chamber deposits and reduces harmful
exhaust emissions. Leaded gasoline is not
recommended and must not be used on EFI engines, or
on other models where exhaust emissions are
regulated.
Gasoline/Alcohol blends
Gasohol (up to 10% ethyl alcohol, 90% unleaded
gasoline by volume) is approved as a fuel for Kohler
engines. Other gasoline/alcohol blends are not
approved.
Gasoline/Ether blends
Methyl Tertiary Butyl Ether (MTBE) and unleaded
gasoline blends (up to a maximum of 15% MTBE by
volume) are approved as a fuel for Kohler engines.
Other gasoline/ether blends are not approved.
Section 1
Safety and General Information
Periodic Maintenance Instructions
1
WARNING: Accidental Starts!
Disabling engine. Accidental starting can cause severe injury or death. Before working on the engine or equipment,
disable the engine as follows: 1) Disconnect the spark plug lead(s). 2) Disconnect negative (-) battery cable from battery.
Maintenance Schedule
These required maintenance procedures should be performed at the frequency stated in the table. They should
also be included as part of any seasonal tune-up.
Frequency
Daily or Before
Starting Engine
Every 25 Hours
Every 100 Hours
Every 200 Hours
Maintenance Required
Refer to:
•
•
•
•
•
•
•
•
•
•
•
•
Section 5
Section 6
Section 4
Section 4
Section 4
Fill fuel tank.
Check oil level.
Check air cleaner for dirty1, loose, or damaged parts.
Check air intake and cooling areas, clean as necessary1.
Service precleaner element1.
Replace air cleaner element1.
Change oil. (More frequently under severe conditions.)
Remove cooling shrouds and clean cooling areas1,3.
Check oil cooler fins, clean as necessary (if equipped).
Check spark plug condition and gap.
Change oil filter.
Check fuel filter (carbureted models)
Section 4
Section 6
Section 4
Section 6
Section 8
Section 6
Section 5
Every 250 Hours
Annually or
Every 500 Hours
• Replace heavy-duty air cleaner element and check inner element1.
• Have bendix starter drive serviced .
• Have solenoid shift starter disassembled and cleaned2.
Section 8
Section 8
Every 500 Hours
• Have crankshaft splines lubricated2.
Section 2
Every 1500 Hours
2
1
• Replace fuel filter (EFI engines).
Section 4
Section 5B
¹Perform these maintenance procedures more frequently under extremely dusty, dirty conditions.
²Only required for Denso starters. Not necessary on Delco starters. Have a Kohler Engine Service Dealer perform this service.
³Cleanout Kits 25 755 20-S (black) or 25 755 21-S (gold) allow cooling areas to be cleaned without removing shrouds.
Storage
If the engine will be out of service for two months or
more, use the following storage procedure:
1. Clean the exterior surfaces of the engine. On
Electronic Fuel Injected (EFI) engines, avoid
spraying water at the wiring harness or any of
the electrical components.
2. Change the oil and oil filter while the engine is
still warm from operation. See “Change Oil and
Oil Filter” in Section 6.
3. The fuel system must be completely emptied, or
the gasoline must be treated with a stabilizer to
prevent deterioration. If you choose to use a
stabilizer, follow the manufacturer’s
recommendations, and add the correct amount
for the capacity of the fuel system.
Fill the fuel tank with clean, fresh gasoline. Run
the engine for 2 to 3 minutes to get stabilized fuel
into the rest of the system. Close the fuel shut-off
valve when the unit is being stored or
transported.
To empty the system, run the engine until the
tank and the system is empty.
4. Remove the spark plugs and add one tablespoon
of engine oil into each spark plug hole. Install the
spark plugs, but do not connect the plug leads.
Crank the engine two or three revolutions.
5. On equipment with an EFI engine, disconnect the
battery or use a battery minder to keep the
battery charged during storage.
6. Store the engine in a clean, dry place.
1.5
Section 1
Safety and General Information
Dimensions in millimeters.
Inch equivalents shown in [ ].
Figure 1-4. Typical Engine Dimensions CV Series with Standard Flat Air Cleaner.
1.6
Section 1
Safety and General Information
Dimensions in millimeters.
Inch equivalents shown in [ ].
Figure 1-5. Typical Engine Dimensions CV Series with Commercial Mower Air Cleaner.
1.7
1
Section 1
Safety and General Information
Dimensions in millimeters.
Inch equivalents shown in [ ].
Figure 1-6. Typical Engine Dimensions CV EFI Series with Heavy-Duty Air Cleaner.
1.8
Section 1
Safety and General Information
General Specifications1
Power (@3600 RPM, exceeds Society of Automotive Engineers-Small Engine Test Code J1940.)
CV17 ........................................................................................................................................... 12.7 kW (17 HP)
CV18 ........................................................................................................................................... 13.4 kW (18 HP)
CV20 ........................................................................................................................................... 14.9 kW (20 HP)
CV22 ........................................................................................................................................... 16.4 kW (22 HP)
CV23 ........................................................................................................................................... 17.2 kW (23 HP)
CV25,CV730 .............................................................................................................................. 18.6 kW (25 HP)
CV26 ........................................................................................................................................... 19.4 kW (26 HP)
CV740 ......................................................................................................................................... 20.1 kW (27 HP)
CV745 ......................................................................................................................................... 20.9 kW (28 HP)
CV750 ......................................................................................................................................... 22.4 kW (30 HP)
1
Peak Torque
CV17 @ 2200 RPM .................................................................................................................... 35.9 N·m (28.7 ft. lb.)
CV18 @ 2200 RPM .................................................................................................................... 42.5 N·m (31.4 ft. lb.)
CV20 @ 2400 RPM .................................................................................................................... 45.1 N·m (33.3 ft. lb.)
CV22 @ 2200 RPM .................................................................................................................... 49.6 N·m (36.6 ft. lb.)
CV23 @ 2400 RPM .................................................................................................................... 54.5 N·m (40.2 ft. lb.)
CV25,CV730 @ 2400 RPM ........................................................................................................ 55.6 N·m (41.0 ft. lb.)
CV26 @ 2800 RPM .................................................................................................................... 54.2 N·m (40.0 ft. lb.)
CV740 @ 2800 RPM .................................................................................................................. 56.9 N·m (42.0 ft. lb.)
CV745 @ 2400 RPM .................................................................................................................. 60.0 N·m (44.3 ft. lb.)
CV750 @ 2600 RPM .................................................................................................................. 63.8 N·m (47.1 ft. lb.)
Bore
CV17 ........................................................................................................................................... 73 mm (2.87 in.)
CV18,CV20,CV22 (624 cc) ....................................................................................................... 77 mm (3.03 in.)
CV22/23 (674 cc) ....................................................................................................................... 80 mm (3.15 in.)
CV25,CV26,CV730-750 ........................................................................................................... 83 mm (3.27 in.)
Stroke
CV17-745 ................................................................................................................................... 67 mm (2.64 in.)
CV750 ......................................................................................................................................... 69 mm (2.7 in.)
Displacement
CV17 ........................................................................................................................................... 561 cc (34 cu. in.)
CV18,CV20,CV22 (624 cc) ....................................................................................................... 624 cc (38 cu. in.)
CV22/23 (674 cc) ....................................................................................................................... 674 cc (41 cu. in.)
CV25,CV26,CV730-745 ........................................................................................................... 725 cc (44 cu. in.)
CV750 ......................................................................................................................................... 755 cc (46 cu. in.)
Compression Ratio
CV17 ........................................................................................................................................... 8.2:1
CV18,CV20,CV22/23 ................................................................................................................ 8.5:1
CV25,CV26,CV730-745 ........................................................................................................... 9.0:1
CV750 ......................................................................................................................................... 9.4:1
Dry Weight
CV17,CV18,CV20,CV22/23 ..................................................................................................... 41 kg (90 lb.)
CV25,CV26,CV730-745 ........................................................................................................... 43 kg (94 lb.)
CV750 ......................................................................................................................................... 48 kg (105 lb.)
1
Values are in Metric units. Values in parentheses are English equivalents. Lubricate threads with engine oil
prior to assembly.
1.9
Section 1
Safety and General Information
General Specifications1 cont.
Oil Capacity (w/filter) - approximate,
determined by oil filter and oil cooler used: ........................................................ 1.6-1.8 L (1.7-1.9 U.S. qt.)
Angle of Operation - Maximum (At Full Oil Level) All Directions .................. 25°
Blower Housing and Sheet Metal
M5 Fasteners Torque ................................................................................................ 6.2 N·m (55 in. lb.) into new holes
4.0 N·m (35 in. lb.) into used holes
M6 Fasteners Torque ................................................................................................ 10.7 N·m (95 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
Rectifier-Regulator Fastener Torque ..................................................................... 1.4 N·m (12.6 in. lb.)
Camshaft
End Play (With Shim) .............................................................................................. 0.076/0.127 mm (0.0030/0.0050 in.)
Running Clearance ................................................................................................... 0.025/0.063 mm (0.0010/0.0025 in.)
Bore I.D.
New ..................................................................................................................... 20.000/20.025 mm (0.7874/0.7884 in.)
Max. Wear Limit ................................................................................................ 20.038 mm (0.7889 in.)
Camshaft Bearing Surface O.D.
New ..................................................................................................................... 19.962/19.975 mm (0.7859/0.7864 in.)
Max. Wear Limit ................................................................................................ 19.959 mm (0.7858 in.)
Carburetor and Intake Manifold
Intake Manifold Mounting Fastener Torque
Torque in Two Stages ........................................................................................ first to 7.4 N·m (66 in. lb.)
finally to 9.9 N·m (88 in. lb.)
Carburetor Mounting Nut Torque ......................................................................... 6.2-7.3 N·m (55-65 in. lb.)
Connecting Rod
Cap Fastener Torque (torque in increments)
8 mm straight shank ......................................................................................... 22.7 N·m (200 in. lb.)
8 mm step-down ............................................................................................... 14.7 N·m (130 in. lb.)
6 mm straight shank ......................................................................................... 11.3 N·m (100 in. lb.)
Connecting Rod-to-Crankpin Running Clearance
New ..................................................................................................................... 0.030/0.055 mm (0.0012/0.0022 in.)
Max. Wear Limit ................................................................................................ 0.070 mm (0.0028 in.)
Connecting Rod-to-Crankpin Side Clearance ...................................................... 0.26/0.63 mm (0.0102/0.0248 in.)
Connecting Rod-to-Piston Pin Running Clearance ............................................. 0.015/0.028 mm (0.0006/0.0011 in.)
Piston Pin End I.D.
New ..................................................................................................................... 17.015/17.023 mm (0.6699/0.6702 in.)
Max. Wear Limit ................................................................................................ 17.036 mm (0.6707 in.)
1
Values are in Metric units. Values in parentheses are English equivalents. Lubricate threads with engine oil
prior to assembly.
1.10
Section 1
Safety and General Information
Crankcase
Governor Cross Shaft Bore I.D.
6 mm Shaft
New .............................................................................................................. 6.025/6.050 mm (0.2372/0.2382 in.)
Max. Wear Limit ........................................................................................ 6.063 mm (0.2387 in.)
8 mm Shaft
New .............................................................................................................. 8.025/8.075 mm (0.3159/0.3179 in.)
Max. Wear Limit ........................................................................................ 8.088 mm (0.3184 in.)
1
Breather Cover Fastener Torque ........................................................................ 7.3 N·m (65 in. lb.)
Oil Drain Plug Torque .......................................................................................... 13.6 N·m (10 ft. lb.)
Oil Pan
Oil Pan Fastener Torque ...................................................................................... 24.4 N·m (216 in. lb.)
Crankshaft
End Play (Free) ...................................................................................................... 0.070/0.590 mm (0.0028/0.0230 in.)
Crankshaft Bore (In Crankcase)
New ................................................................................................................. 40.965/41.003 mm (1.6128/1.6143 in.)
Max. Wear Limit ............................................................................................ 41.016 mm (1.6148 in.)
Crankshaft to Sleeve Bearing (Crankcase)
Running Clearance - New ............................................................................ 0.03/0.09 mm (0.0012/0.0035 in.)
Crankshaft Bore (In Oil Pan) - New ................................................................... 40.987/40.974 mm (1.6136/1.6131 in.)
Crankshaft Bore (In Oil Pan)-to-Crankshaft
Running Clearance - New ............................................................................ 0.039/0.074 mm (0.0015/0.0029 in.)
Flywheel End Main Bearing Journal
O.D. - New ...................................................................................................... 40.913/40.935 mm (1.6107/1.6116 in.)
O.D. - Max. Wear Limit ................................................................................. 40.84 mm (1.608 in.)
Max. Taper ...................................................................................................... 0.022 mm (0.0009 in.)
Max. Out-of-Round ....................................................................................... 0.025 mm (0.0010 in.)
Oil Pan End Main Bearing Journal
O.D. - New ...................................................................................................... 40.913/40.935 mm (1.6107/1.6116 in.)
O.D. - Max. Wear Limit ................................................................................. 40.84 mm (1.608 in.)
Max. Taper ...................................................................................................... 0.022 mm (0.0009 in.)
Max. Out-of-Round ....................................................................................... 0.025 mm (0.0010 in.)
Connecting Rod Journal
O.D. - New ...................................................................................................... 35.955/35.973 mm (1.4156/1.4163 in.)
O.D. - Max. Wear Limit ................................................................................. 35.94 mm (1.415 in.)
Max. Taper ...................................................................................................... 0.018 mm (0.0007 in.)
Max. Out-of-Round ....................................................................................... 0.025 mm (0.0010 in.)
Crankshaft T.I.R.
PTO End, Crank in Engine ............................................................................ 0.279 mm (0.0110 in.)
Entire Crank, in V-Blocks ............................................................................. 0.10 mm (0.0039 in.)
1.11
Section 1
Safety and General Information
Cylinder Bore
Cylinder Bore I.D.
New - CV17 ............................................................................................. 73.006/73.031 mm (2.8742/2.8752
New - CV18,CV20,CV22 (624 cc) ......................................................... 77.000/77.025 mm (3.0315/3.0325
New - CV22/23 (674 cc) ......................................................................... 80.000/80.025 mm (3.1496/3.1506
New - CV25,CV26,CV730-750 ............................................................. 82.988/83.013 mm (3.2672/3.2682
Max. Wear Limit - CV17 ........................................................................ 73.070 mm (2.8757 in.)
Max. Wear Limit - CV18,CV20,CV22 (624 cc) .................................... 77.063 mm (3.0340 in.)
Max. Wear Limit - CV22/23 (674 cc) .................................................... 80.065 mm (3.1522 in.)
Max. Wear Limit - CV25,CV26,CV730-750 ........................................ 83.051 mm (3.2697 in.)
Max. Out-of-Round CV17 ..................................................................... 0.13 mm (0.0051 in.)
Max. Out-of-Round CV18-750 ............................................................. 0.12 mm (0.0047 in.)
Max. Taper ............................................................................................... 0.05 mm (0.0020 in.)
in.)
in.)
in.)
in.)
Cylinder Head
Cylinder Head Fastener Torque
Hex Flange Nut - Torque in Two Stages .............................................. first to 16.9 N·m (150 in. lb.)
finally to 33.9 N·m (300 in. lb.)
Head Bolt - Torque in Two Stages ........................................................ first to 22.6 N·m (200 in. lb.)
finally to 41.8 N·m (370 in. lb.)
Max. Out-of-Flatness ..................................................................................... 0.076 mm (0.003 in.)
Rocker Arm Screw Torque ........................................................................... 11.3 N·m (100 in. lb.)
Fan/Flywheel
Fan Fastener Torque ...................................................................................... 9.9 N·m (88 in. lb.)
Flywheel Retaining Screw Torque .............................................................. 66.4 N·m (49 ft. lb.)
Governor
Governor Cross Shaft-to-Crankcase Running Clearance
6 mm Shaft .............................................................................................. 0.013/0.075 mm (0.0005/0.0030 in.)
8 mm Shaft .............................................................................................. 0.025/0.126 mm (0.0009/0.0049 in.)
Governor Cross Shaft O.D.
6 mm Shaft
New .......................................................................................................
Max. Wear Limit ..................................................................................
8 mm Shaft
New .......................................................................................................
Max. Wear Limit ..................................................................................
5.975/6.012 mm (0.2352/0.2367 in.)
5.962 mm (0.2347 in.)
7.949/8.000 mm (0.3129/0.3149 in.)
7.936 mm (0.3124 in.)
Governor Gear Shaft-to-Governor
Gear Running Clearance ....................................................................... 0.015/0.140 mm (0.0006/0.0055 in.)
Governor Gear Shaft O.D.
New .......................................................................................................... 5.990/6.000 mm (0.2358/0.2362 in.)
Max. Wear Limit ..................................................................................... 5.977 mm (0.2353 in.)
Governor Lever Nut Torque ........................................................................ 6.8 N·m (60 in. lb.)
1.12
Section 1
Safety and General Information
Ignition
Spark Plug Type (Champion® or Equivalent) ............................................. RC12YC, XC12YC, or Platinum 3071
1
Spark Plug Gap ............................................................................................... 0.76 mm (0.030 in.)
Spark Plug Torque .......................................................................................... 24.4-29.8 N·m (18-22 ft. lb.)
Ignition Module Air Gap ............................................................................... 0.28/0.33 mm (0.011/0.013 in.)
Ignition Module Fastener Torque ................................................................. 4.0-6.2 N·m (35-55 in. lb.)
Speed Sensor Air Gap (EFI engines) ............................................................. 1.50 ± 0.25 mm (0.059 ± 0.010 in.)
Muffler
Muffler Retaining Nuts Torque .................................................................... 24.4 N·m (216 in. lb.)
Oil Filter
Oil Filter Torque .............................................................................................. 3/4 - 1 turn after gasket contact
Oil Cooler
Oil Cooler/Adapter Nipple Torque .............................................................. 27 N·m (20 ft. lb.)
Piston, Piston Rings, and Piston Pin
Piston-to-Piston Pin Running Clearance .................................................... 0.006/0.017 mm (0.0002/0.0007 in.)
Piston Pin Bore I.D.
New ........................................................................................................... 17.006/17.012 mm (0.6695/0.6698 in.)
Max. Wear Limit ...................................................................................... 17.025 mm (0.6703 in.)
Piston Pin O.D.
New ........................................................................................................... 16.995/17.000 mm (0.6691/0.6693 in.)
Max. Wear Limit ...................................................................................... 16.994 mm (0.6691 in.)
Top Compression Ring-to-Groove Side Clearance
CV17 .......................................................................................................... 0.040/0.085
CV18,CV20,CV22 (624 cc) ...................................................................... 0.040/0.080
CV22/23 (674 cc) ...................................................................................... 0.030/0.076
CV25,CV26,CV730-750 .......................................................................... 0.025/0.048
mm
mm
mm
mm
(0.0016/0.0033
(0.0016/0.0031
(0.0012/0.0030
(0.0010/0.0019
in.)
in.)
in.)
in.)
Middle Compression Ring-to-Groove Side Clearance
CV17 .......................................................................................................... 0.030/0.080
CV18,CV20,CV22 (624 cc) ...................................................................... 0.040/0.080
CV22/23 (674 cc) ...................................................................................... 0.030/0.076
CV25,CV26,CV730-750 .......................................................................... 0.015/0.037
mm
mm
mm
mm
(0.0012/0.0031
(0.0016/0.0031
(0.0012/0.0030
(0.0006/0.0015
in.)
in.)
in.)
in.)
Oil Control Ring-to-Groove Side Clearance
CV17 .......................................................................................................... 0.046/0.201
CV18,CV20,CV22 (624 cc) ...................................................................... 0.060/0.202
CV22/23 (674 cc) ...................................................................................... 0.046/0.196
CV25,CV26,CV730-750 .......................................................................... 0.026/0.176
mm
mm
mm
mm
(0.0018/0.0079
(0.0024/0.0080
(0.0018/0.0077
(0.0010/0.0070
in.)
in.)
in.)
in.)
1.13
Section 1
Safety and General Information
Piston, Piston Rings, and Piston Pin cont.
Top and Middle Compression Ring End Gap
New Bore - CV17
Top Ring ............................................................................................... 0.180/0.380 mm (0.0071/0.0150 in.)
Middle Ring ......................................................................................... 0.180/0.440 mm (0.0071/0.0173 in.)
New Bore - CV18,CV20,CV22 (624 cc) ................................................. 0.25/0.45 mm (0.0098/0.0177 in.)
New Bore - CV22 (674 cc) ....................................................................... 0.18/0.46 mm (0.0071/0.0181 in.)
New Bore - CV25,CV26,CV730-750 ..................................................... 0.25/0.56 mm (0.0100/0.0224 in.)
Used Bore (Max.) - CV17
Top Ring ............................................................................................... 0.70 mm (0.028 in.)
Middle Ring ......................................................................................... 0.90 mm (0.035 in.)
Used Bore (Max.) - CV18,CV20,CV22 (624 cc) ..................................... 0.77 mm (0.030 in.)
Used Bore (Max.) - CV22/23 (674 cc) ..................................................... 0.80 mm (0.0315 in.)
Used Bore (Max.) - CV25,CV26,CV730-750 ......................................... 0.94 mm (0.037 in.)
Piston Thrust Face O.D.²
New - CV17 .............................................................................................. 72.966/72.984 mm (2.8727/2.8734 in.)
New - CV18,CV20,CV22 (624 cc) .......................................................... 76.967/76.985 mm (3.0302/3.0309 in.)
New - CV22/23 (674 cc) .......................................................................... 79.963/79.979 mm (3.1481/3.1488 in.)
New - CV25,CV26,CV730-750 .............................................................. 82.986 mm (3.2671 in.)
Max. Wear Limit - CV17 ......................................................................... 72.839 mm (2.8677 in.)
Max. Wear Limit - CV18,CV20,CV22 (624 cc) ..................................... 76.840 mm (3.0252 in.)
Max. Wear Limit - CV22 (674 cc) ........................................................... 79.831 mm (3.1430 in.)
Max. Wear Limit - CV25,CV26,CV730-750 ......................................... 82.841 mm (3.2614 in.)
Piston Thrust Face-to-Cylinder Bore² Running Clearance
New - CV17 .............................................................................................. 0.022/0.065
New - CV18,CV20,CV22 (624 cc) .......................................................... 0.014/0.057
New - CV22/23 (674 cc) .......................................................................... 0.021/0.062
New - CV25,CV26,CV730-750 .............................................................. 0.001/0.045
mm (0.0009/0.0026 in.)
mm (0.0005/0.0022 in.)
mm (0.0008/0.0024 in.)
mm (0.039/0.0018 in.)
Speed Control Bracket
Fastener Torque ............................................................................................... 10.7 N·m (95 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
Starter Assembly
Thru Bolt Torque
UTE/Johnson Electric, Eaton (Inertia Drive) ......................................... 4.5-5.7 N·m (40-50 in. lb.)
Nippondenso (Solenoid Shift) ................................................................ 4.5-7.5 N·m (40-84 in. lb.)
Delco-Remy (Solenoid Shift) .................................................................. 5.6-9.0 N·m (49-79 in. lb.)
Mounting Screw Torque (All) ....................................................................... 15.3 N·m (135 in. lb.)
Brush Holder Mounting Screw Torque
Delco-Remy Starter ................................................................................. 2.5-3.3 N·m (22-29 in. lb.)
Solenoid (Starter)
Mounting Hardware Torque
Nippondenso Starter .............................................................................. 6.0-9.0 N·m (53-79 in. lb.)
Delco-Remy Starter ................................................................................. 4.0-6.0 N·m (35-53 in. lb.)
Nut, Positive (+) Brush Lead Torque
Nippondenso Starter .............................................................................. 8.0-12.0 N·m (71-106 in. lb.)
Delco-Remy Starter ................................................................................. 8.0-11.0 N·m (71-97 in. lb.)
²Measure 6 mm (0.236 in.) above the bottom of the piston skirt at right angles to the piston pin.
1.14
Section 1
Safety and General Information
Stator
Mounting Screw Torque ................................................................................ 6.2 N·m (55 in. lb.)
1
Valve Cover
Valve Cover Fastener Torque
Gasket Style Cover .................................................................................. 3.4 N·m (30 in. lb.)
Black O-Ring Style Cover
w/Shoulder Screws ............................................................................ 5.6 N·m (50 in. lb.)
w/Flange Screws and Spacers .......................................................... 9.9 N·m (88 in. lb.)
Yellow or Brown O-Ring Style Cover w/Integral Metal Spacers ..... 6.2 N·m (55 in. lb.)
Valves and Valve Lifters
Hydraulic Valve Lifter to Crankcase Running Clearance ........................ 0.0241/0.0501 mm (0.0009/0.0020 in.)
Intake Valve Stem-to-Valve Guide Running Clearance ........................... 0.038/0.076 mm (0.0015/0.0030 in.)
Exhaust Valve Stem-to-Valve Guide Running Clearance ........................ 0.050/0.088 mm (0.0020/0.0035 in.)
Intake Valve Guide I.D.
New ........................................................................................................... 7.038/7.058 mm (0.2771/0.2779 in.)
Max. Wear Limit ...................................................................................... 7.134 mm (0.2809 in.)
Exhaust Valve Guide I.D.
New ........................................................................................................... 7.038/7.058 mm (0.2771/0.2779 in.)
Max. Wear Limit ...................................................................................... 7.159 mm (0.2819 in.)
Valve Guide Reamer Size
Standard ................................................................................................... 7.048 mm (0.2775 in.)
0.25 mm O.S. ............................................................................................. 7.298 mm (0.2873 in.)
Intake Valve Minimum Lift ........................................................................... 8.07 mm (0.3177 in.)
Exhaust Valve Minimum Lift ....................................................................... 8.07 mm (0.3177 in.)
Nominal Valve Seat Angle ............................................................................ 45°
1.15
Section 1
Safety and General Information
General Torque Values
Metric Fastener Torque Recommendations for Standard Applications
Tightening Torque: N·m (in. lb.) + or - 10%
Property Class
4.8
Size
M4
M5
M6
M8
1.2 (11)
2.5 (22)
4.3 (38)
10.5 (93)
5.8
1.7 (15)
3.2 (28)
5.7 (50)
13.6 (120)
8.8
2.9 (26)
5.8 (51)
9.9 (88)
24.4 (216)
Noncritical
Fasteners
Into Aluminum
10.9
4.1 (36)
8.1 (72)
14.0 (124)
33.9 (300)
12.9
5.0 (44)
9.7 (86)
16.5 (146)
40.7 (360)
2.0 (18)
4.0 (35)
6.8 (60)
17.0 (150)
Tightening Torque: N·m (ft. lb.) + or - 10%
Property Class
M10
M12
M14
1.16
4.8
5.8
21.7 (16)
36.6 (27)
58.3 (43)
27.1 (20)
47.5 (35)
76.4 (55)
8.8
47.5 (35)
82.7 (61)
131.5 (97)
Noncritical
Fasteners
Into Aluminum
10.9
12.9
66.4 (49)
116.6 (86)
184.4 (136)
81.4 (60)
139.7 (103)
219.7 (162)
33.9 (25)
61.0 (45)
94.9 (70)
Section 1
Safety and General Information
English Fastener Torque Recommendations for Standard Applications
1
Tightening Torque: N·m (in. lb.) + or - 20%
Bolts, Screws, Nuts and Fasteners
Assembled Into Cast Iron or Steel
Grade 2
Size
8-32
10-24
10-32
1/4-20
1/4-28
5/16-18
5/16-24
3/8-16
3/8-24
2.3 (20)
3.6 (32)
3.6 (32)
7.9 (70)
9.6 (85)
17.0 (150)
18.7 (165)
29.4 (260)
33.9 (300)
Grade 2 or 5
Fasteners Into
Aluminum
Grade 5
2.8 (25)
4.5 (40)
4.5 (40)
13.0 (115)
15.8 (140)
28.3 (250)
30.5 (270)
-----------------
Grade 8
------------------------18.7 (165)
22.6 (200)
39.6 (350)
-------------------------
2.3 (20)
3.6 (32)
--------7.9 (70)
--------17.0 (150)
-------------------------
Tightening Torque: N·m (ft. lb.) + or - 20%
Size
5/16-24
3/8-16
3/8-24
7/16-14
7/16-20
1/2-13
1/2-20
9/16-12
9/16-18
5/8-11
5/8-18
3/4-10
3/4-16
------------------------47.5 (35)
61.0 (45)
67.8 (50)
94.9 (70)
101.7 (75)
135.6 (100)
149.2 (110)
189.8 (140)
199.3 (150)
271.2 (200)
---------47.5 (35)
54.2 (40)
74.6 (55)
101.7 (75)
108.5 (80)
142.4 (105)
169.5 (125)
223.7 (165)
244.1 (180)
311.9 (230)
332.2 (245)
440.7 (325)
40.7 (30)
67.8 (50)
81.4 (60)
108.5 (80)
142.4 (105)
155.9 (115)
223.7 (165)
237.3 (175)
311.9 (230)
352.6 (260)
447.5 (330)
474.6 (350)
637.3 (470)
---------------------------------------------------------------------------------------------------------
Torque
Conversions
N·m = in. lb. x 0.113
N·m = ft. lb. x 1.356
in. lb. = N·m x 8.85
ft. lb. = N·m x 0.737
1.17
Section 2
Tools & Aids
Section 2
Tools & Aids
2
Certain quality tools are designed to help you perform specific disassembly, repair, and reassembly procedures.
By using tools designed for the job, you can properly service engines easier, faster, and safer! In addition, you’ll
increase your service capabilities and customer satisfaction by decreasing engine downtime.
Here is the list of tools and their source.
Separate Tool Suppliers:
Kohler Tools
Contact your source
of supply.
SE Tools
415 Howard St.
Lapeer, MI 48446
Phone 810-664-2981
Toll Free 800-664-2981
Fax 810-664-8181
Design Technology Inc.
768 Burr Oak Drive
Westmont, IL 60559
Phone 630-920-1300
Tools
Description
Source/Part No.
Balance Gear Tim ing Tool (K & M Ser ies)
To hold balance gears in timed position when assembling engine.
Kohler 25 455 06-S
(Formerly Y-357)
Cam shaft Endplay Plat e
For checking camshaft endplay.
S E Tools KLR-82405
Cylinder Leakdow n Test er
For checking combustion retention and if cylinder, piston, rings, or valves are worn.
Kohler 25 761 05-S
Elect r onic Fuel Inject ion (EFI) Diagnost ic Soft w ar e
U se with Laptop or Desktop PC.
EFI Ser vice Kit
For troubleshooting and setting up an EFI engine.
Individual Components Available
Pressure Tester
Noid Light
90° Adapter
Oetiker Clamp Pliers
Code Plug, Red Wire
Code Plug, Blue Wire
Kohler 25 761 23-S
Kohler 24 761 01-S
Design Technology Inc.
DTI-019
DTI-021
DTI-023
DTI-025
DTI-027
DTI-029
Flyw heel Holding Tool (CS Ser ies)
S E Tools KLR-82407
Flyw heel Puller
To remove flywheel from engine.
S E Tools KLR-82408
2.1
Section 2
Tools & Aids
Tools (cont.)
Description
Source/Part No.
Flyw heel St r ap Wr ench
To hold flywheel during removal.
S E Tools KLR-82409
Hydr aulic Valve Lift er Tool
To remove and install hydraulic lifters.
Kohler 25 761 38-S
Ignit ion Syst em Test er
For testing output on all systems, except CD.
For testing output on capacitive discharge (CD) ignition system.
Kohler 25 455 01-S
Kohler 24 455 02-S
Offset Wr ench (K & M Ser ies)
To remove and reinstall cylinder barrel retaining nuts.
S E Tools KLR-82410
Oil Pr essur e Test Kit
To test and verify oil pressure.
Kohler 25 761 06-S
Rect ifier -Regulat or Test er (120 volt cur r ent )
Rect ifier -Regulat or Test er (240 volt cur r ent )
U sed to test rectifier-regulators.
Kohler 25 761 20-S
Kohler 25 761 41-S
Individual Components Available
CS -PRO Regulator Test Harness
S pecial Regulator Test Harness with Diode
Design Technology Inc.
DTI-031
DTI-033
Spar k Advance Module (SAM) Test er
To test the S AM (AS AM and DS AM) on engines with S MART-S PARK™.
Kohler 25 761 40-S
St ar t er Br ush Holding Tool (Solenoid Shift )
To hold brushes during servicing.
S E Tools KLR-82416
St ar t er Ret aining Ring Tool (Iner t ia Dr ive)
To remove and reinstall drive retaining rings (excluding FAS CO starters).
Kohler 25 761 18-S
St ar t er Ser vicing Kit (All St ar t er s)
To remove and reinstall drive retaining rings and brushes.
S E Tools KLR-82411
Individual Component Available
S tarter Brush Holding Tool (S olenoid S hift)
Tachom et er (Digit al Induct ive)
For checking operating speed (RPM) of an engine.
S E Tools KLR-82416
Design Technology Inc.
DTI-110
Vacuum /Pr essur e Test er
Alternative to a water manometer.
Kohler 25 761 22-S
Valve Guide Ream er (K & M Ser ies)
For sizing valve guides after installation.
S E Tools KLR-82413
Valve Guide Ser vice Kit (Cour age, Aegis, Com m and, OHC)
For servicing worn value guides.
S E Tools KLR-82415
2.2
Section 2
Tools & Aids
Aids
Description
Source/Part No.
Cam shaft Lubr icant (Valspar ZZ613)
Kohler 25 357 14-S
Dielect r ic Gr ease (GE/Novaguard G661)
Kohler 25 357 11-S
Dielect r ic Gr ease (Fel-Pro)
Lubri-S el
Elect r ic St ar t er Dr ive Lubr icant (Inertia Drive)
Kohler 52 357 01-S
Elect r ic St ar t er Dr ive Lubr icant (S olenoid S hift)
Kohler 52 357 02-S
RTV Silicone Sealant
Loctite® 5900 Heavy Body in 4 oz aerosol dispenser.
Kohler 25 597 07-S
Only oxime-based, oil resistant RTV sealants, such as those listed, are approved for use.
Loctite® Nos. 5900 or 5910 are recommended for best sealing characteristics.
Loctite®
Loctite®
Loctite®
Loctite®
5910
U ltra Black 598
U ltra Blue 587
U ltra Copper
Spline Dr ive Lubr icant
Kohler 25 357 12-S
2.3
2
Section 2
Tools & Aids
Special Tools You Can Make
Flywheel Holding Tool
A flywheel holding tool can be made out of an old
junk flywheel ring gear as shown in Figure 2-1, and
used in place of a strap wrench.
1. Using an abrasive cut-off wheel, cut out a six
tooth segment of the ring gear as shown.
2. Grind off any burrs or sharp edges.
3. Invert the segment and place it between the
ignition bosses on the crankcase so that the tool
teeth engage the flywheel ring gear teeth. The
bosses will lock the tool and flywheel in
position for loosening, tightening or removing
with a puller.
2. Remove the studs of a Posi-Lock rod or grind off
the aligning steps of a Command rod, so the joint
surface is flat.
3. Find a 1 in. long capscrew with the correct
thread size to match the threads in the
connecting rod.
4. Use a flat washer with the correct I.D. to slip on
the capscrew and approximately 1” O.D. (Kohler
Part No. 12 468 05-S). Assemble the capscrew
and washer to the joint surface of the rod, as
shown in Figure 2-2.
Figure 2-2. Rocker Arm/Crankshaft Tool.
Figure 2-1. Flywheel Holding Tool.
Rocker Arm/Crankshaft Tool
A spanner wrench to lift the rocker arms or turn the
crankshaft may be made out of an old junk connecting
rod.
1. Find a used connecting rod from a 10 HP or
larger engine. Remove and discard the rod cap.
2.4
Section 3
Troubleshooting
Section 3
Troubleshooting
Troubleshooting Guide
When troubles occur, be sure to check the simple
causes which, at first, may seem too obvious to be
considered. For example, a starting problem could be
caused by an empty fuel tank.
Some general common causes of engine troubles are
listed below. Use these to locate the causing factors.
Refer to the specific section(s) within this service
manual for more detailed information.
Engine Cranks But Will Not Start
1. Empty fuel tank.
2. Fuel shut-off valve closed.
3. Poor fuel, dirt or water in the fuel system.
4. Clogged fuel line.
5. Spark plug lead(s) disconnected.
6. Key switch or kill switch in “off” position.
7. Faulty spark plugs.
8. Faulty ignition module(s).
9. SMART-SPARK™ malfunction (applicable
models).
10. Carburetor solenoid malfunction.
11. Diode in wiring harness failed in open circuit
mode.
12. Vacuum fuel pump malfunction, or oil in vacuum
hose.
13. Vacuum hose to fuel pump leaking/cracked.
14. Battery connected backwards.
15. Safety interlock system engaged.
Engine Starts But Does Not Keep Running
1. Restricted fuel tank cap vent.
2. Poor fuel, dirt or water in the fuel system.
3. Faulty or misadjusted choke or throttle controls.
4. Loose wires or connections that short the kill
terminal of ignition module to ground.
5. Faulty cylinder head gasket.
6. Faulty carburetor.
7. Vacuum fuel pump malfunction, or oil in vacuum
hose.
8. Leaking/cracked vacuum hose to fuel pump.
9. Intake system leak.
3
10. Diode in wiring harness failed in open circuit
mode.
Engine Starts Hard
1. PTO drive is engaged.
2. Dirt or water in the fuel system.
3. Clogged fuel line.
4. Loose or faulty wires or connections.
5. Faulty or misadjusted choke or throttle controls.
6. Faulty spark plugs.
7. Low compression.
8. Faulty ACR mechanism (equipped models).
9. Weak spark.
10. Fuel pump malfunction causing lack of fuel.
11. Engine overheated-cooling/air circulation
restricted.
12. Quality of fuel.
13. Flywheel key sheared.
14. Intake system leak.
Engine Will Not Crank
1. PTO drive is engaged.
2. Battery is discharged.
3. Safety interlock switch is engaged.
4. Loose or faulty wires or connections.
5. Faulty key switch or ignition switch.
6. Faulty electric starter or solenoid.
7. Seized internal engine components.
Engine Runs But Misses
1. Dirt or water in the fuel system.
2. Spark plug lead disconnected.
3. Poor quality of fuel.
4. Faulty spark plug(s).
5. Loose wires or connections that intermittently
ground the ignition kill circuit.
6. Engine overheated.
7. Faulty ignition module or incorrect air gap.
8. Carburetor adjusted incorrectly.
9. SMART-SPARK™ malfunction (applicable
models).
3.1
Section 3
Troubleshooting
Engine Will Not Idle
1. Dirt or water in the fuel system.
2. Stale fuel and/or gum in carburetor.
3. Faulty spark plugs.
4. Fuel supply inadequate.
5. Idle fuel adjusting needle improperly set (some
models).
6. Idle speed adjusting screw improperly set.
7. Low compression.
8. Restricted fuel tank cap vent.
9. Engine overheated-cooling system/air circulation
problem.
Engine Overheats
1. Air intake/grass screen, cooling fins, or cooling
shrouds clogged.
2. Excessive engine load.
3. Low crankcase oil level.
4. High crankcase oil level.
5. Faulty carburetor.
6. Lean fuel mixture.
7. SMART-SPARK™ malfunction (applicable
models).
Engine Knocks
1. Excessive engine load.
2. Low crankcase oil level.
3. Old or improper fuel.
4. Internal wear or damage.
5. Hydraulic lifter malfunction.
6. Quality of fuel.
7. Incorrect grade of oil.
Engine Loses Power
1. Low crankcase oil level.
2. High crankcase oil level.
3. Dirty air cleaner element.
4. Dirt or water in the fuel system.
5. Excessive engine load.
6. Engine overheated.
7. Faulty spark plugs.
8. Low compression.
9. Exhaust restriction.
10. SMART-SPARK™ malfunction (applicable
models).
11. Low battery.
12. Incorrect governor setting.
3.2
Engine Uses Excessive Amount of Oil
1. Incorrect oil viscosity/type.
2. Clogged or improperly assembled breather.
3. Breather reed broken.
4. Worn or broken piston rings.
5. Worn cylinder bore.
6. Worn valve stems/valve guides.
7. Crankcase overfilled.
8. Blown head gasket/overheated.
Oil Leaks from Oil Seals, Gaskets
1. Crankcase breather is clogged or inoperative.
2. Breather reed broken.
3. Loose or improperly torqued fasteners.
4. Piston blowby, or leaky valves.
5. Restricted exhaust.
External Engine Inspection
Before cleaning or disassembling the engine, make a
thorough inspection of its external appearance and
condition. This inspection can give clues to what
might be found inside the engine (and the cause)
when it is disassembled.
•
Check for buildup of dirt and debris on the
crankcase, cooling fins, grass screen, and other
external surfaces. Dirt or debris on these areas are
causes of higher operating temperatures and
overheating.
•
Check for obvious fuel and oil leaks, and
damaged components. Excessive oil leakage can
indicate a clogged or improperly-assembled
breather, worn/damaged seals and gaskets, or
loose or improperly-torqued fasteners.
•
Check the air cleaner cover and base for damage
or indications of improper fit and seal.
•
Check the air cleaner element. Look for holes,
tears, cracked or damaged sealing surfaces, or
other damage that could allow unfiltered air into
the engine. Also note if the element is dirty or
clogged. These could indicate that the engine has
been under serviced.
•
Check the carburetor throat for dirt. Dirt in the
throat is further indication that the air cleaner is
not functioning properly.
•
Check the oil level. Note if the oil level is within
the operating range on the dipstick, or if it is low
or overfilled.
Section 3
Troubleshooting
• Check the condition of the oil. Drain the oil into a
container - the oil should flow freely. Check for
metal chips and other foreign particles.
Sludge is a natural by-product of combustion; a
small accumulation is normal. Excessive sludge
formation could indicate overrich carburetion,
weak ignition, overextended oil change intervals
or wrong weight or type of oil was used, to name
a few.
NOTE: It is good practice to drain oil at a
location away from the workbench. Be
sure to allow ample time for complete
drainage.
Cleaning the Engine
After inspecting the external condition of the engine,
clean the engine thoroughly before disassembling it.
Also clean individual components as the engine is
disassembled. Only clean parts can be accurately
inspected and gauged for wear or damage. There are
many commercially available cleaners that will
quickly remove grease, oil, and grime from engine
parts. When such a cleaner is used, follow the
manufacturer’s instructions and safety precautions
carefully.
To test the crankcase vacuum with the manometer:
1. Insert the stopper/hose into the oil fill hole. Leave
the other tube of manometer open to atmosphere.
Make sure the shut off clamp is closed.
2. Start the engine and run at no-load high speed
(3200 to 3750 RPM).
3
3. Open the clamp and note the water level in the
tube.
The level in the engine side should be a
minimum of 10.2 cm (4 in.) above the level in the
open side.
If the level in the engine side is less than
specified (low/no vacuum), or the level in the
engine side is lower than the level in the open
side (pressure), check for the conditions in the
table below.
4. Close the shut off clamp before stopping the
engine.
To test the crankcase vacuum with the Vacuum/
Pressure Gauge Kit:
Make sure all traces of the cleaner are removed before
the engine is reassembled and placed into operation.
Even small amounts of these cleaners can quickly
break down the lubricating properties of engine oil.
1. Remove the dipstick or oil fill plug/cap.
Basic Engine Tests
3. Push the barbed fitting on the gauge solidly into
the hole in the adapter.
Crankcase Vacuum Test
A partial vacuum should be present in the crankcase
when the engine is operating. Pressure in the
crankcase (normally caused by a clogged or
improperly assembled breather) can cause oil to be
forced out at oil seals, gaskets, or other available spots.
Crankcase vacuum is best measured with either a
water manometer, or a vacuum gauge (see Section 2).
Complete instructions are provided in the kits.
2. Install the adapter into the oil fill/dipstick tube
opening.
4. Start the engine and bring it up to operating
speed (3200-3600 RPM).
5. Check the reading on the gauge. If the reading is
to the left of “0” on the gauge, vacuum or
negative pressure is indicated. If the reading is to
the right of “0” on the gauge, positive pressure is
present.
Crankcase vacuum should be 4-10 (inches of
water). If the reading is below specification, or if
pressure is present, check the following table for
possible causes and remedies.
3.3
Section 3
Troubleshooting
No Crankcase Vacuum/Pressure in Crankcase
Possible Cause
Solution
1. Crankcase breather clogged or inoperative.
1. Disassemble breather, clean parts thoroughly,
reassemble, and recheck pressure.
2. Seals and/or gaskets leaking. Loose or
improperly torqued fasteners.
2. Replace all worn or damaged seals and gaskets.
Make sure all fasteners are tightened securely.
Use appropriate torque values and sequences
when necessary.
3. Piston blowby or leaky valves (confirm by
inspecting components).
3. Recondition piston, rings, cylinder bore, valves,
and valve guides.
4. Restricted exhaust.
4. Repair/replace restricted muffler/exhaust
system.
Compression Test
Some of these engines are equipped with an automatic
compression release (ACR) mechanism. Because of the
ACR mechanism, it is difficult to obtain an accurate
compression reading. As an alternative, perform a
cylinder leakdown test.
Cylinder Leakdown Test
A cylinder leakdown test can be a valuable alternative
to a compression test. By pressurizing the combustion
chamber from an external air source you can
determine if the valves or rings are leaking, and how
badly.
Cylinder Leakdown Tester (see Section 2) is a
relatively simple, inexpensive leakdown tester for
small engines. The tester includes a quick disconnect
for attaching the adapter hose, and a holding tool.
Leakdown Test Instructions
1. Run the engine for 3-5 minutes to warm it up.
2. Remove the spark plug(s) and the air filter from
engine.
3. Rotate the crankshaft until the piston (of cylinder
being tested) is at top dead center of the
compression stroke. Hold the engine in this
position while testing. The holding tool supplied
with the tester can be used if the PTO end of the
crankshaft is accessible. Lock the holding tool
onto the crankshaft. Install a 3/8" breaker bar into
the hole/slot of the holding tool, so it is
perpendicular to both the holding tool and
crankshaft PTO.
3.4
If the flywheel end is more accessible, use a
breaker bar and socket on the flywheel nut/
screw to hold it in position. An assistant may be
needed to hold the breaker bar during testing. If
the engine is mounted in a piece of equipment, it
may be possible to hold it by clamping or
wedging a driven component. Just be certain that
the engine cannot rotate off of TDC in either
direction.
4. Install the adapter into the spark plug hole, but
do not attach it to the tester at this time.
5. Connect an air source of at least 50 psi to the
tester.
6. Turn the regulator knob in the increase
(clockwise) direction until the gauge needle is in
the yellow “set” area at the low end of the scale.
7. Connect the tester quick-disconnect to the
adapter hose while firmly holding the engine at
TDC. Note the gauge reading and listen for
escaping air at the carburetor intake, exhaust
outlet, and crankcase breather.
8. Check the test results against the following table:
Section 3
Troubleshooting
Leakdown Test Results
Air escaping from crankcase breather ...................................................... Rings or cylinder worn.
Air escaping from exhaust system ............................................................ Defective exhaust valve/improper seating.
Air escaping from carburetor ..................................................................... Defective intake valve/improper seating.
Gauge reading in “low” (green) zone ........................................................Piston rings and cylinder in good condition.
Gauge reading in “moderate” (yellow) zone ............................................Engine is still usable, but there is some
wear present. Customer should start
planning for overhaul or replacement.
Gauge reading in “high” (red) zone .......................................................... Rings and/or cylinder have considerable
wear. Engine should be reconditioned or
replaced.
3.5
3
Section 4
Air Cleaner and Air Intake System
Section 4
Air Cleaner and Air Intake System
Air Cleaners
General
These engines are equipped with a replaceable, highdensity paper air cleaner element. Most are also
equipped with an oiled-foam precleaner which
surrounds the paper element.
Three different types are used. The “standard” type air
cleaner is shown in Figure 4-1. The “commercial
mower” type is shown in Figure 4-2, and the “heavyduty” air cleaner is shown in Figure 4-9.
Service
Check the air cleaner daily or before starting the
engine. Check for and correct any buildup of dirt and
debris, along with loose or damaged components.
NOTE: Operating the engine with loose or damaged
air cleaner components could allow
unfiltered air into the engine causing
premature wear and failure.
Precleaner Service (Standard and Commercial
Mower Types)
If so equipped, wash and reoil the precleaner every 25
hours of operation (more often under extremely dusty
or dirty conditions).
To service the precleaner, see Figures 4-3 or 4-4 and
perform the following steps:
1. Loosen the cover retaining knob or unhook the
latches and remove the cover.
2. Remove the foam precleaner from the paper air
cleaner element.
Figure 4-1. Standard Air Cleaner.
3. Wash the precleaner in warm water with
detergent. Rinse the precleaner thoroughly until
all traces of detergent are eliminated. Squeeze out
excess water (do not wring). Allow the precleaner
to air dry.
4. Saturate the precleaner with new engine oil.
Squeeze out all excess oil.
5. Reinstall the precleaner over the paper air cleaner
element.
6. Reinstall the air cleaner cover. Secure the cover
with the two latches or the retaining knob.
Figure 4-2. Commercial Mower Air Cleaner.
4.1
4
Section 4
Air Cleaner and Air Intake System
Precleaner
Paper Element Service (Standard and Commercial
Mower Types)
Every 100 hours of operation (more often under
extremely dusty or dirty conditions), replace the paper
element. See Figures 4-5 or 4-6, and follow these steps:
1. Unhook the latches or loosen the cover retaining
knob and remove the cover.
2. Remove the wing nut, element cover, and air
cleaner element.
Element
Figure 4-3. Precleaner on Standard Air Cleaner.
Precleaner
Element
3. Remove the precleaner (if so equipped) from the
paper element. Service the precleaner as
described in “Precleaner Service”.
4. Do not wash the paper element or use
pressurized air, as this will damage the element.
Replace a dirty, bent, or damaged element with a
genuine Kohler element. Handle new elements
carefully; do not use if the sealing surfaces are
bent or damaged.
5. Check the rubber sleeve seal for any damage or
deterioration. Replace as necessary.
6. Reinstall the paper element, precleaner, element
cover, and wing nut.
Figure 4-4. Precleaner on Commercial Mower Type
Air Cleaner.
4.2
7. Reinstall the air cleaner cover and secure with the
two latches or the retaining knob.
Section 4
Air Cleaner and Air Intake System
Air Cleaner Base
Spitback Cup
Precleaner
Spitback
Cup Gasket
Rubber Seal
4
Air Cleaner Cover
Element
Knob Seal
Element
Cover Nut
Element Cover
Knob
Figure 4-5. Air Cleaner System Components - Standard.
*Plenum air cleaner system does not use a precleaner.
Element Cover Nut
Wing Nut
Element Cover
Air Cleaner
Cover
(Plenum*)
Element
Cover
Retaining
Knob
Rubber
Seal
Stud
Air Cleaner
Cover (Std.)
Precleaner
Air
Cleaner
Base
Figure 4-6. Air Cleaner System Components - Commercial Mower Type.
4.3
Section 4
Air Cleaner and Air Intake System
Air Cleaner Components
Whenever the air cleaner cover is removed, or the
paper element or precleaner are serviced, check the
following:
Air Cleaner Element Cover and Seal - Make sure
element cover is not bent or damaged. Make sure the
rubber sleeve seal is in place on the stud to prevent
dust or dirt entry through the stud hole.
4. Remove the base and gasket. Carefully feed the
breather hose through the base.
5. Reverse procedure to reassemble components.
Torque the two hex flange nuts to 6.2-7.3 N·m
(55-65 in. lb.) and the two lower M5 mounting
screws (where applicable) to 4.0 N·m (35 in. lb.).
Air Cleaner Base - Make sure the base is secured
tightly to the carburetor and not cracked or damaged.
Breather Tube - Make sure the tube is attached to both
the air cleaner base and the oil separator.
NOTE: Damaged, worn or loose air cleaner
components can allow unfiltered air into the
engine causing premature wear and failure.
Tighten or replace all loose or damaged
components.
Mounting
Nuts (2)
Breather Hose
Baffle
Seal
Lower Base
Mounting Screws
Base
Figure 4-7. Base Plate Removal on Standard Type.
Disassembly/Reassembly - Standard Type
If the base plate on the standard type has to be
removed, proceed as follows:
1. Remove the air cleaner components from the base
(see Figure 4-5).
2. Remove the two hex flange nuts securing the
bracket, or spitback cup with seal and baffle (if
equipped) to base. If a plastic intake manifold is
used, remove the two lower base mounting
screws. See Figure 4-7.
3. Pinch the sealing collar on the breather hose and
push it down through the hole in the base.
4.4
Figure 4-8. Removing Base on Commercial Mower
Type Air Cleaner.
Disassembly/Reassembly - Commercial Mower Type
If the base has to be separated from the carburetor
proceed as follows:
1. Remove the air cleaner components from the air
cleaner base (see Figure 4-6).
2. Remove the two nuts holding the air cleaner base
to the carburetor (see Figure 4-8).
3. Remove the tube from the base.
4. Separate the base from the carburetor.
5. Reverse procedure to reassemble components.
Torque air cleaner base mounting nuts to
6.2-7.3 N·m (55-65 in. lb.).
Section 4
Air Cleaner and Air Intake System
Heavy-Duty Air Cleaner
General
The heavy-duty air cleaner consists of a cylindrical
housing, typically mounted to a bracket, and
connected with a formed rubber hose to an adapter on
the carburetor or throttle body/intake manifold (EFI
units). The air cleaner housing contains a paper
element and inner element, designed for longer
service intervals. The system is CARB/EPA certified
and the components should not be altered or modified
in any way.
Element
Inner Element
4
Figure 4-10. Removing Elements.
3. After the element is removed, check the condition
of the inner element. It should be replaced
whenever it appears dirty, typically every other
time the main element is replaced. Clean the area
around the base of the inner element before
removing it, so dirt does not get into the engine.
Figure 4-9. Heavy-Duty Air Cleaner.
To Service
Every 250 hours of operation (more often under
extremely dusty or dirty conditions), replace the
paper element and check the inner element. Follow
these steps.
1. Unhook the two retaining clips and remove the
end cap from the air cleaner housing.
2. Pull the air cleaner element out of the housing.
See Figure 4-10.
4. Do not wash the paper element and inner
element or use compressed air, this will damage
the elements. Replace dirty, bent or damaged
elements with new genuine Kohler elements as
required. Handle the new elements carefully; do
not use if the sealing surfaces are bent or
damaged.
5. Check all parts for wear, cracks, or damage.
Replace any damaged components.
6. Install the new inner element, followed by the
outer element. Slide each fully into place in the
air cleaner housing.
7. Reinstall the end cap so the dust ejector valve is
down, and secure with the two retaining clips.
See Figure 4-9.
4.5
Section 4
Air Cleaner and Air Intake System
Air Intake/Cooling System
To ensure proper cooling, make sure the grass screen,
cooling fan fins, and other external surfaces of the
engine are kept clean at all times.
Every 100 hours of operation (more often under
extremely dusty or dirty conditions), remove the
blower housing and other cooling shrouds.* Clean the
cooling fins and external surfaces as necessary. Make
sure the cooling shrouds are reinstalled.
*Cleanout kits, Kohler Part No. 25 755 20-S (black) or
25 755 21-S (gold), are recommended to aid
inspection and cleanout of the cooling fins. See
Figure 4-11.
NOTE: Operating the engine with a blocked grass
screen, dirty or plugged cooling fins, and/or
cooling shrouds removed, will cause engine
damage due to overheating.
4.6
Figure 4-11. Cleanout Kit Installed on Blower
Housing.
Section 5
Fuel System and Governor
Section 5
Fuel System and Governor
Description
The Command vertical twins use two different types
of fuel systems; carbureted, or electronic fuel injection
(EFI).
This section covers the standard carbureted fuel
systems. The EFI fuel systems are covered in
subsection 5B. The governor systems used are covered
at the end of this section.
WARNING: Explosive Fuel!
Gasoline is extremely flammable and its vapors can explode
if ignited. Store gasoline only in approved containers, in
well ventilated, unoccupied buildings, away from sparks or
flames. Do not fill the fuel tank while the engine is hot or
running, since spilled fuel could ignite if it comes in contact
with hot parts or sparks from ignition. Do not start the
engine near spilled fuel. Never use gasoline as a cleaning
agent.
Fuel System Components
The typical carbureted fuel system and related
components include the following:
•
•
•
•
•
Fuel Tank
Fuel Lines
In-line Fuel Filter
Fuel Pump
Carburetor
Operation
The fuel from the tank is moved through the in-line
filter and fuel lines by the fuel pump. On engines not
equipped with a fuel pump, the fuel tank outlet is
located above the carburetor inlet allowing gravity to
feed fuel to the carburetor.
Fuel then enters the carburetor float bowl and is
drawn into the carburetor body. There, the fuel is
mixed with air. This fuel-air mixture is then burned in
the engine combustion chamber.
Fuel Recommendations
General Recommendations
Purchase gasoline in small quantities and store in
clean, approved containers. A container with a
capacity of 2 gallons or less with a pouring spout is
recommended. Such a container is easier to handle
and helps eliminate spillage during refueling.
5
•
Do not use gasoline left over from the previous
season, to minimize gum deposits in your fuel
system and to ensure easy starting.
•
Do not add oil to the gasoline.
•
Do not overfill the fuel tank. Leave room for the
fuel to expand.
Fuel Type
For best results, use only clean, fresh, unleaded
gasoline with a pump sticker octane rating of 87 or
higher. In countries using the Research fuel rating
method, it should be 90 octane minimum.
Unleaded gasoline is recommended as it leaves less
combustion chamber deposits and reduces harmful
exhaust emissions. Leaded gasoline is not
recommended and must not be used on EFI engines,
or on other models where exhaust emissions are
regulated.
Gasoline/Alcohol blends
Gasohol (up to 10% ethyl alcohol, 90% unleaded
gasoline by volume) is approved as a fuel for Kohler
engines. Other gasoline/alcohol blends are not
approved.
Gasoline/Ether blends
Methyl Tertiary Butyl Ether (MTBE) and unleaded
gasoline blends (up to a maximum of 15% MTBE by
volume) are approved as a fuel for Kohler engines.
Other gasoline/ether blends are not approved.
5.1
Section 5
Fuel System and Governor
Fuel Filter
Most engines are equipped with an in-line filter.
Periodically inspect the filter and replace with a
genuine Kohler filter every 200 operating hours.
Fuel Line
In compliance with CARB Tier III Emission
Regulations, carbureted engines with a “Family”
identification number beginning with “6” or greater
(See Figure 5-1), must use Low Permeation SAE 30 R7
rated fuel line; certified to meet CARB requirements.
Standard fuel line may not be used. Order
replacement hose by part number through a Kohler
Engine Service Dealer.
IMPORTANT ENGINE INFORMATION
THIS ENGINE MEETS U.S. EPA AND CA 2005
AND LATER AND EC STAGE II (SN:4) EMISSION
REGS FOR SI SMALL OFF–ROAD ENGINES
FAMILY
6 KHXS.7252 PH
TYPE APP
DISPL. (CC)
N11236
MODEL NO.
SPEC. NO.
SERIAL NO.
BUILD DATE
OEM PROD. NO.
EMISSION COMPLIANCE PERIOD:
EPA:
CARB:
CERTIFIED ON:
REFER TO OWNER'S MANUAL FOR HP RATING,
SAFETY, MAINTENANCE AND ADJUSTMENTS
1-800-544-2444 www.kohlerengines.com
KOHLER CO. KOHLER, WISCONSIN USA
Figure 5-1. “Family” Number Location.
5.2
Section 5
Fuel System and Governor
Fuel System Tests
When the engine starts hard, or turns over but will not start, it is possible that the problem is in the fuel system.
To find out if the fuel system is causing the problem, perform the following tests.
Troubleshooting – Fuel System Related Causes
Test
Conclusion
1. Check the following:
a. Make sure the fuel tank contains clean, fresh,
proper fuel.
b. Make sure the vent in fuel tank cap is open.
c. Make sure the fuel valve is open.
d. Make sure vacuum and fuel lines to fuel
pump are secured and in good condition.
2. Check for fuel in the combustion chamber.
a. Disconnect and ground spark plug leads.
b. Close the choke on the carburetor.
c. Crank the engine several revolutions.
d. Remove the spark plug and check for fuel at
the tip.
2. If there is fuel at the tip of the spark plug, fuel is
reaching the combustion chamber.
3. Check for fuel flow from the tank to the fuel
pump.
a. Remove the fuel line from the inlet fitting of
fuel pump.
b. Hold the line below the bottom of the tank.
Open the shut-off valve (if so equipped) and
observe flow.
3. If fuel does flow from the line, check for faulty
fuel pump (Test 4).
4. Check the operation of fuel pump.
a. Remove the fuel line from the inlet fitting of
carburetor.
b. Crank the engine several times and observe
flow.
4. If fuel does flow from the line, check for faulty
carburetor. (Refer to the "Carburetor" portions of
this section).
If there is no fuel at the tip of the spark plug,
check for fuel flow from the fuel tank (Test 3).
If fuel does not flow from the line, check the fuel
tank vent, fuel pickup screen, in-line filter, shutoff valve, and fuel line. Correct any observed
problem and reconnect the line.
If fuel does not flow from the line, check for a
clogged fuel line. If the fuel line is unobstructed,
check for overfilled crankcase and/or oil in pulse
line. If none of the checks reveal the cause of the
problem, replace the pump.
5.3
5
Section 5
Fuel System and Governor
Fuel Pump
3. Remove the pulse line that connects the pump to
the crankcase.
General
These engines are equipped with a pulse type fuel
pump. The pumping action is created by the
oscillation of positive and negative pressures within
the crankcase. This pressure is transmitted to the pulse
pump through a rubber hose connected between the
pump and crankcase. The pumping action causes the
diaphragm on the inside of the pump to pull fuel in
on its downward stroke and to push it into the
carburetor on its upward stroke. Two check valves
prevent fuel from going backward through the pump.
4. Install a new pump using the hex flange screws.
NOTE: Make sure the orientation of the new
pump is consistent with the removed
pump. Internal damage may occur if
installed incorrectly.
5. Connect the pulse line between the pump and
crankcase.
6. Torque the hex flange screws to 2.3 N·m
(20 in. lb.).
Inlet Line
Carburetor
Outlet Line (to
Carburetor)
Pulse Line
Figure 5-2. Pulse Pump Connections.
Performance
Minimum fuel delivery rate must be 7.5 L/hr. (2 gal./
hr.) with a pressure at 0.3 psi and a fuel lift of 24 in. A
1.3 L/hr. (0.34 gal./hr.) fuel rate must be maintained at
5 Hz.
Replacing the Fuel Pump
Replacement pumps are available through your
source of supply. To replace the pulse pump follow
these steps. Note orientation of pump before
removing.
1. Disconnect the fuel lines from the inlet and outlet
fittings.
2. Remove the hex flange screws (securing pump)
and fuel pump.
5.4
7. Connect the fuel lines to the inlet and outlet
fittings.
General
CV17-740 engines in this series are equipped with
either a Nikki or Keihin one-barrel, fixed main jet
carburetor. Some applications use a fuel shut-off
solenoid installed in place of the fuel bowl retaining
screw, and also an accelerator pump. All carburetors
feature a self-relieving choke like or similar to the one
shown in the exploded view on page 5.12. These
carburetors include three main circuits, which
function as described following. CV750 engines use a
Keihin BK two-barrel carburetor on a matching intake
manifold. This carburetor with related servicing and
adjustments is covered beginning on page 5.20.
CV17-740 Engines
Float Circuit: The fuel level in the bowl is maintained
by the float and fuel inlet needle. The buoyant force of
the float stops fuel flow when the engine is at rest.
When fuel is being consumed, the float will drop and
fuel pressure will push the inlet needle away from the
seat, allowing more fuel to enter the bowl. When
demand ceases, the buoyant force of the float will
again overcome the fuel pressure and stop the flow.
Section 5
Fuel System and Governor
Slow Circuit: (See Figure 5-3) At low speeds the engine operates only on the slow circuit. As a metered amount
of air is drawn through the slow air bleed jet, fuel is drawn through the main jet and further metered through the
slow jet. Air and fuel are mixed in the body of the slow jet and exit to the transfer port. From the transfer port
this air fuel mixture is delivered to the idle progression chamber. From the idle progression chamber the air fuel
mixture is metered through the idle port passage. At low idle when the vacuum signal is weak, the air fuel
mixture is controlled by the setting of the idle fuel adjusting screw. This mixture is then mixed with the main
body of air and delivered to the engine. As the throttle plate opening increases, greater amounts of air fuel
mixture are drawn in through the fixed and metered idle progression holes. As the throttle plate opens further
the vacuum signal becomes great enough so the main circuit begins to work.
Keihin Carburetors Only
Idle Speed
(RPM)
Adjustment
Screw
Low (Idle) Mixture Screw
Spring
5
Idle Limiter Jet
Fuel Inlet
Idle Port
Float
Float Valve Seat
Float Valve
Main Emulsion
Hole
Main Jet
Idle Progression
Chamber
Slow
Jet
Idle Limiter
Jet
Idle Port
Slow Air Bleed Jet
Main Air Bleed Jet
Choke Valve
Capped/Preset
Low (Idle)
Mixture Setting
Idle
Progression
Holes
Accelerator Pump Nozzle
Bowl Vent
Check Valve Spring
Throttle Valve
Leak Jet
Outlet Check Valve
Main Nozzle
Adjustment Screw
Slow Passage Pipe
Diaphragm Spring
Pump Diaphragm
Air
Inlet Check Valve
Fuel
Mixture
Main Jet
ACCELERATOR PUMP
ASSEMBLY
(Some Carburetors)
Fuel Shut-Off Solenoid
with Main Jet
Figure 5-3. Slow Circuit.
5.5
Section 5
Fuel System and Governor
Main Circuit: (See Figure 5-4) At high speeds/loads the engine operates on the main circuit. As a metered
amount of air is drawn through the main air bleed jet, fuel is drawn through the main jet. The air and fuel are
mixed in the main nozzle and then enter the main body of airflow, where further mixing of the fuel and air takes
place. This mixture is then delivered to the combustion chamber. The carburetor has a fixed main circuit; no
adjustment is possible.
Air
Idle Speed
(RPM)
Adjustment
Screw
Fuel
Mixture
Fuel Inlet
Float
Float Valve Seat
Float Valve
Main Emulsion
Hole
Main Jet
Main Air Bleed Jet
Choke Valve
Accelerator Pump Nozzle
Bowl Vent
Check Valve Spring
Throttle Valve
Leak Jet
Outlet Check Valve
Main Nozzle
Adjustment Screw
Diaphragm Spring
Pump Diaphragm
Inlet Check Valve
Main Jet
ACCELERATOR PUMP
ASSEMBLY
(Some Carburetors)
Figure 5-4. Main Circuit.
5.6
Fuel Shut-Off Solenoid
with Main Jet
Section 5
Fuel System and Governor
Troubleshooting – Carburetor Related Causes
Condition
Possible Cause/Probable Remedy
1. Engine starts hard, runs roughly
1. Low idle fuel mixture/speed improperly adjusted. Adjust the low
or stalls at idle speed.
idle speed screw, then adjust the low idle fuel needle.
2. Engine runs rich (indicated by
2a. Clogged air cleaner. Clean or replace.
black, sooty exhaust smoke,
b. Choke partially closed during operation. Check the choke lever/
misfiring, loss of speed and power,
linkage to ensure choke is operating properly.
governor hunting, or excessive
c. Low idle fuel mixture is improperly adjusted. Adjust low idle
throttle opening).
fuel needle.
d. Float level too high. Separate fuel bowl from carburetor body.
Free (if stuck), or replace float.
e. Dirt under the fuel inlet needle. Remove needle; clean needle and
seat and blow with compressed air.
f. Bowl vent or air bleeds plugged. Remove low idle fuel adjusting
needle. Clean vent, ports, and air bleeds. Blow out all passages
with compressed air.
g. Leaky, cracked, or damaged float. Submerge float to check for
leaks.
3. Engine runs lean (indicated by
3a. Low idle fuel mixture is improperly adjusted. Adjust low idle
misfiring, loss of speed and power,
fuel needle.
governor hunting, or excessive
b. Float level too low. Separate fuel bowl from carburetor body. Free
throttle opening).
(if stuck), or replace float.
c. Idle holes plugged; dirt in fuel delivery channels. Remove low
idle fuel adjusting needle. Clean main fuel jet and all passages;
blow out with compressed air.
4. Fuel leaks from carburetor.
4a.
b.
c.
d.
Float stuck. See Remedy 2d.
Dirt under fuel inlet needle. See Remedy 2e.
Bowl vents plugged. Blow out with compressed air.
Carburetor bowl gasket leaks. Replace gasket.
Troubleshooting Checklist
When the engine starts hard, runs roughly or stalls at
low idle speed, check the following areas before
adjusting or disassembling the carburetor.
•
Make sure the fuel tank is filled with clean, fresh
gasoline.
•
Make sure the fuel tank cap vent is not blocked
and that it is operating properly.
•
Make sure fuel is reaching the carburetor. This
includes checking the fuel shut-off valve, fuel
tank filter screen, in-line fuel filter, fuel lines and
fuel pump for restrictions or faulty components
as necessary.
•
Make sure the air cleaner base and carburetor are
securely fastened to the engine using gaskets in
good condition.
•
Make sure the air cleaner element (including the
precleaner if equipped) is clean, and all air
cleaner components are fastened securely.
•
Make sure the ignition system, governor system,
exhaust system, and throttle and choke controls
are operating properly.
If the engine is hard-starting, runs roughly or stalls at
low idle speed, it may be necessary to service the
carburetor.
5.7
5
Section 5
Fuel System and Governor
High Altitude Operation
When operating the engine at altitudes of 1500 m
(5000 ft.) and above, the fuel mixture tends to get overrich. This can cause conditions such as black, sooty
exhaust smoke, misfiring, loss of speed and power,
poor fuel economy, and poor or slow governor
response.
To compensate for the effects of high altitude, special
high altitude jet kits are available. The kits include a
new main jet, slow jet (where applicable), necessary
gaskets and O-Rings. Refer to the parts manual for the
correct kit number.
Fuel Shut-off Solenoid
Some carburetors are equipped with an optional fuel
shut-off solenoid. The solenoid is installed in place of
the bowl retaining screw. The solenoid has a springloaded pin that retracts when 12 volt current is
applied to the lead. When it is extended, the main fuel
jet is blocked, preventing normal carburetor operation.
Below is a simple test, made with the engine off, that
can determine if the solenoid is functioning properly:
1. Shut off the fuel and remove the solenoid from
the carburetor. When the solenoid is loosened
and removed, gas will leak out of the carburetor.
Have a container ready to catch the fuel. The
main jet is mounted in the tip of the solenoid pin.
Be careful that it does not get damaged while the
solenoid is separated from the carburetor.
2. Wipe the tip of the solenoid with a shop towel or
blow it off with compressed air, to remove any
remaining fuel. Take the solenoid to a location
with good ventilation and no fuel vapors present.
You will also need a 12 volt power source that can
be switched on and off.
3. Be sure the power source is switched “off”.
Connect the positive power source lead to the red
lead of the solenoid. Connect the negative power
source lead to the solenoid body.
4. Turn the power source “on” and observe the pin
in the center of the solenoid. The pin should
retract with the power “on” and return to its
original position with the power off. Test several
times to verify operation.
5.8
Fuel Shut-Off
Solenoid
Figure 5-5. Fuel Shut-off Solenoid Location.
Carburetor Adjustments (CV17-740)
General
The carburetor is designed to deliver the correct fuelto-air mixture to the engine under all operating
conditions. The high speed mixture adjustment is set
at the factory and cannot be adjusted. The low idle
fuel adjusting needle (some models) is also set at the
factory and normally does not need adjustment.
Depending on model and application, engines may
also be equipped with a “Governed Idle System.” If
equipped with a “Governed Idle System”, refer to
“Models with Governed Idle System” when
performing any carburetor adjustment, as an
additional step to the listed adjustment procedure(s) is
required.
NOTE: Carburetor adjustments should be made only
after the engine has warmed up.
NOTE: Certified engines may have a fixed idle or
limiter cap on the idle fuel adjusting needle.
Do not attempt steps 1 and 2 below. Proceed
directly to step 3. Step 5 can only be
performed within the limits allowed by the
cap.
Adjusting Low Idle Fuel and Speed
To adjust the carburetor idle fuel and speed, see
Figure 5-6 and follow these steps.
1. With the engine stopped, turn the low idle fuel
adjusting needle (if equipped) in (clockwise) until
it bottoms lightly.
Section 5
Fuel System and Governor
NOTE: The tip of the idle fuel adjusting needle
is tapered to critical dimensions.
Damage to the needle and the seat in the
carburetor body will result if the needle
is forced.
Low Idle Fuel
Adjustment
(Some Models)
5. Low Idle Fuel Needle Setting: Place the throttle
into the “idle” or “slow” position. Turn the low
idle fuel adjusting needle in (slowly) until engine
speed decreases and then back out approximately
3/4 to 1 turn to obtain the best low speed
performance.
6. Recheck the idle speed using a tachometer and
readjust the speed as necessary.
Models with Governed Idle System
Low Idle Speed
(RPM) Adjustment
An optional governed idle control system is supplied
on some engines. The purpose of this system is to
maintain a desired idle speed regardless of ambient
conditions (temperature, parasitic load, etc.) that may
change. Engines with this feature contain a small
secondary spring connected between the governor
lever and the lower adjustment tab of the main
bracket. See Figure 5-7.
Figure 5-6. Carburetor Adjustments.
2. Preliminary Settings: Turn the adjusting needle
out (counterclockwise) from lightly bottomed
2-1/4 turns.
3. Start the engine and run at half throttle for 5 to 10
minutes to warm up. The engine must be warm
before making final settings. Check that the
throttle and choke plates can fully open.
NOTE: The carburetor has a self-relieving
choke. The choke plate and shaft
assembly is spring loaded. Check to
make sure the plate moves freely and is
not binding, affecting idle fuel delivery.
4. Low Idle Speed Setting: Place the throttle control
into the “idle” or “slow” position. Set the low
idle speed to 1200 RPM* (± 75 RPM) by turning
the low idle speed adjusting screw in or out.
Check the speed using a tachometer.
*NOTE: The actual low idle speed depends on
the application. Refer to the equipment
manufacturer’s recommendations. The
low idle speed for basic engines is 1200
RPM. To ensure best results when setting
the low idle fuel needle, the low idle
speed should be 1200 RPM (± 75 RPM).
The system requires an additional procedure for
setting the idle speed. If speed adjustments are
required proceed as follows.
1. Make any necessary speed or control adjustments
following the appropriate instructions covered in
this section.
2. Move the throttle control to the idle position.
Hold the governor lever away from the
carburetor, or hold the throttle lever so it is tight
against the idle speed adjusting screw, to negate
the governor activation. See Figure 5-8. Check the
speed with a tachometer and adjust it to 1500
RPM.
3. Release the governor lever and allow the engine
to return to the governed idle speed. Check it
with a tachometer against the equipment
manufacturers recommended idle speed.
Governed Idle Speed (RPM) is typically 300 RPM
(approximate) higher than the low idle speed. If
adjustment is necessary, bend the adjusting tab on
the speed control assembly to set. See Figure 5-7.
5.9
5
Section 5
Fuel System and Governor
5. Slide the carburetor off the retaining studs.
Remove the fuel bowl retaining screw or fuel
shut-off solenoid and drain the fuel into a safe
container. Remove the bowl from the carburetor
body.
Governed
Idle Spring
Tab
16.5 mm
(0.65 in.)
Figure 5-7. Governed Idle Spring Location.
Hold Throttle
Lever Against
Screw
Figure 5-8. Holding Throttle Lever Against Idle
Stop Screw (One-Barrel Carburetor).
Carburetor Servicing (CV17-740)
Nikki Carburetors
Float Replacement
If symptoms described in the carburetor
troubleshooting guide indicate float level problems,
remove the carburetor from the engine to check and/or
replace the float. Use a float kit to replace float, pin
and inlet needle or valve.
1. Remove the air cleaner and air intake components
from the carburetor as described in Section 4.
2. Disconnect the fuel inlet line from the carburetor.
3. Disconnect governor/throttle linkage from the
carburetor.
4. Disconnect lead wires from fuel solenoidequipped carburetor.
5.10
Turn Carburetor
Upside Down
Figure 5-9. Proper Float Level.
6. Turn the carburetor body upside down and check
the float level as shown in Figure 5-9. With the
float needle valve fully seated, 16.5 mm (0.65 in.)
should be measured from the body to the float as
indicated. Don’t attempt to adjust by bending the
tab; replace the float with a kit if the level is
wrong.
7. Pull the float hinge pin and remove the float with
the inlet needle attached to inspect the needle and
seat. If dirty, blow out with compressed air.
Replace the float components as needed with the
kit.
8. Using new gaskets, reinstall the bowl and tighten
the bowl retaining screw or solenoid to
5.1-6.2 N·m (45-55 in. lb.).
9. Reinstall the carburetor on the engine, reconnect
the fuel line, control linkages and air intake
components. Retest operation.
Section 5
Fuel System and Governor
Disassembly
Use the carburetor repair kit (and the float repair kit if
float components are to be replaced). Refer to Figure
5-10 for parts identification. The Kohler part number
and the Nikki lot number are stamped on the choke
side flange on top of the carburetor body. Refer to the
parts manual for the carburetor involved to ensure the
correct repair kits and replacement parts are used.
Disassemble carburetor as follows after removal from
the engine. See Figure 5-10.
1. Remove the fuel bowl retaining screw or solenoid
assembly, then remove the bowl and bowl gasket.
On solenoid-equipped carburetors, the main jet is
mounted in the tip of the solenoid pin. Be careful
that it does not get damaged while the solenoid is
separated from the carburetor.
2. Pull the float hinge pin, and remove the float with
the inlet needle attached.
3. Remove the vent plug from the column on fuel
solenoid-equipped carburetors.
4. Remove the screws holding the throttle plate to
the throttle shaft, pull the throttle shaft from the
carburetor body.
5. Remove the screws securing the choke plate to
the choke shaft assembly and pull the choke shaft
assembly out of the carburetor body. Disassemble
the self-relieving parts from shaft as needed.
6. Remove the three screws holding the passage
cover to the body, remove the cover gasket.
7. Remove the idle fuel adjusting needle and spring
if it does not have a limiter. Remove the idle
speed screw and spring. Except for the slow jet
nozzle, main jet, and emulsion tubes, which are
considered non-serviceable, the carburetor is now
completely disassembled and ready for thorough
inspection and cleaning.
5.11
5
Section 5
Fuel System and Governor
6
4
26
2
18
5
1
24
3
25
7
17
23
21
8
16
22
15
20
9
10
19
14
or
11
13
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
Carburetor Body
Idle Fuel Adjusting Screw*
Idle Fuel Adjusting Spring*
Passage Cover
Cover Gasket*
Cover Retaining Screw
Main Jet
Ground Lead (Solenoid only)
Fuel Bowl Gasket
Float Kit
Fuel Bowl
Bowl Retaining Screw Gasket
Bowl Retaining Screw
Shut-off Solenoid Assembly
Throttle Shaft/Lever
Throttle Plate
Choke Shaft
Choke Plate
Air Filter
Collar
Spring
Ring
Choke Lever
Idle Speed Screw
Idle Speed Spring
Setscrews (Plates - 4)
*Included in Carburetor Repair Kit.
12
Figure 5-10. Typical Carburetor - Exploded View.
Inspection/Repair
To clean vent ports, seats etc., use a good
commercially available carburetor solvent, such as
Gumout™, and clean, dry compressed air to blow out
internal channels and ports. Use a suitable shop rag to
prevent debris from hitting someone.
•
Inspect the float for cracks, holes, and missing or
damaged float tabs. Check the float hinge and
shaft for wear or damage.
•
Inspect the fuel inlet needle and seat for wear or
damage.
Carefully inspect all components and replace those
that are worn or damaged.
•
Inspect the tip of the low idle fuel adjusting
needle (if equipped), for wear or grooves.
•
The choke plate is spring loaded. Check to make
sure it moves freely.
•
5.12
Inspect the carburetor body for cracks, holes and
other wear or damage.
Section 5
Fuel System and Governor
Always use new gaskets when servicing or reinstalling
carburetors. Repair kits are available which include
new gaskets and other components. Service/repair kits
available for Nikki carburetors and affiliated
components are:
Carburetor Repair Kit
Float Kit
High Altitude Kit (1525-3048 m/5,000-10,000 ft.)
High Altitude Kit (Over 3048 m/10,000 ft.)
Solenoid Assembly Kit
Reassembly Procedure
Reassembly is essentially the reverse of the
disassembly procedure. Use new gaskets, springs and
adjusting screws as provided in the carburetor repair
kit. Also use new carburetor and intake manifold
gaskets. Set the idle speed (RPM) adjusting screw (if
equipped) 2-1/4 turns open for initial adjustment and
make final adjustments as described earlier.
Keihin Carburetors (CV17-740)
Figure 5-12. Removing Float and Inlet Needle.
3. Clean the carburetor bowl and inlet seat areas as
required, before installation of new parts.
4. Attach the inlet needle to the metal tang of the
float with the wire clip. The formed 90° lip of the
metal tang should point up, with the needle valve
hanging down. See Figure 5-13.
Float Replacement
1. Clean the exterior surfaces of dirt or foreign
material before disassembling the carburetor.
Unseat the clamp and disconnect the accelerator
pump hose (if so equipped), from the upper
fitting. Remove the four fuel bowl screws and
carefully separate the fuel bowl from the
carburetor. Do not damage the O-Ring(s).
Transfer any remaining fuel into an approved
container. Save all parts. See Figure 5-11.
Figure 5-13. Float and Inlet Needle.
5. Install the float and inlet needle down into the
seat and carburetor body. Insert the new pivot pin
through the float hinge and secure with the new
retaining screw. See Figure 5-14.
Figure 5-11. Fuel Bowl Removed from Carburetor.
2. Remove the float pin screw and lift out the old
float, pin, and inlet needle. See Figure 5-12.
Discard all of the parts. The seat for the inlet
needle is not serviceable, and should not be
removed.
5.13
5
Section 5
Fuel System and Governor
8. When the proper float height is obtained,
carefully reinstall the fuel bowl, with the
O-Ring(s) in place, onto the carburetor. Secure
with the four original screws. Torque the screws
to 2.5 ± 0.3 N·m (23 ± 2.6 in. lb.). Reattach the
accelerator pump hose (if so equipped), and
secure with the clip. See Figure 5-16.
Figure 5-14. Installing Float Assembly.
6. Hold the carburetor body so the float assembly
hangs vertically and rests lightly against the fuel
inlet needle. The inlet needle should be fully
seated but the center pin of the needle (on
retainer clip end) should not be depressed. Check
the float height adjustment.
NOTE: The inlet needle center pin is spring loaded.
Make sure the float assembly rests against the
fuel inlet needle without depressing the
center pin.
7. The correct float height adjustment is 12.0 mm
(0.472 in.) measured from the float bottom to the
body of the carburetor. See Figure 5-15. Adjust
the float height by carefully bending the metal
tang of the float.
Figure 5-16. Installing Fuel Bowl.
Disassembly/Overhaul
1. Clean the exterior surfaces of dirt or foreign
material before disassembling the carburetor.
Unseat the clamp and disconnect the accelerator
pump hose (if so equipped), from the upper
fitting. Remove the four fuel bowl screws and
separate the fuel bowl from the carburetor.
Transfer any remaining fuel into an approved
container. Remove and discard the old O-Ring(s).
See Figure 5-17.
Figure 5-15. Checking Float Height.
Figure 5-17. Fuel Bowl Removed from Carburetor.
NOTE: Be sure to measure from the casting
surface, not the rubber gasket, if still
attached.
5.14
NOTE: Further disassembly of fuel bowl is not
necessary unless the Accelerator Pump Kit
24 757 47-S, or Fuel Solenoid Kit 24 757 45-S
(obtained separately), are also being installed.
Section 5
Fuel System and Governor
2. Remove the float pin screw and lift out the old
float, pin, and inlet needle. See Figure 5-18.
Discard all of the parts. The seat for the inlet
needle is not serviceable, and should not be
removed.
Figure 5-18. Removing Float and Inlet Needle.
3. Remove and discard the round plug from the
bottom of the slow jet tower of the carburetor
body. Use an appropriate size flat screwdriver,
and carefully remove the slow and main jets from
the carburetor. After the main jet has been
removed, the main nozzle can be taken out
through the bottom of the main tower. Save the
parts for cleaning and reuse. See Figure 5-19.
Figure 5-19. Main Jet and Slow Jet Removed.
4. Remove the two screws securing the top cover,
gasket, and ground lead (fuel solenoid-equipped
models). Discard the gasket and screws only.
NOTE: The carburetor is now disassembled for
appropriate cleaning and installation of
the parts in the overhaul kit. Further
disassembly is not necessary. The
throttle shaft assembly, fuel inlet seat,
and bowl chamber baffle, are nonserviceable items and should not be
removed. The choke shaft assembly is
serviceable, however it should not be
removed unless a Choke Repair Kit
24 757 36-S will be installed.
6. Clean the carburetor body, jets, vent ports, seats,
etc., using a good commercially available
carburetor solvent. Use clean, dry compressed air
to blow out the internal channels and ports.
Inspect and thoroughly check the carburetor for
cracks, wear, or damage. Inspect the fuel inlet seat
for wear or damage. Check the spring loaded
choke plate to make sure it moves freely on the
shaft.
7. Clean the carburetor float bowl as required. If it
has an accelerator pump that is not being serviced
at this time, prevent the cleaning solvent from
contacting the check valve and accelerator pump
components.
8. Install the main nozzle and the main jet into the
tower of the carburetor body. See Figure 5-20.
Figure 5-20. Installing Main Nozzle and Main Jet.
9. Install the slow jet and new plug into end of slow
jet tube. See Figures 5-21 and 5-22.
5. Remove the idle speed and idle fuel adjusting
screws and springs from the carburetor. Discard
the parts.
5.15
5
Section 5
Fuel System and Governor
11. Install the float and inlet needle down into the
seat and carburetor body. Insert the new pivot pin
through the float hinge and secure with the new
retaining screw. See Figure 5-24.
Figure 5-21. Installing Slow Jet.
Figure 5-24. Installing Float Assembly.
12. Hold the carburetor body so the float assembly
hangs vertically and rests lightly against the fuel
inlet needle. The inlet needle should be fully
seated but the center pin of the needle (on
retainer clip end) should not be depressed. Check
the float height adjustment.
Figure 5-22. Installing Plug into Slow Jet Tube.
10. Attach the inlet needle to the metal tang of the
float with the wire clip. The formed 90° lip of the
metal tang should point up, with the needle valve
hanging down. See Figure 5-23.
NOTE: The inlet needle center pin is spring
loaded. Make sure the float assembly
rests against the fuel inlet needle,
without depressing the center pin.
13. The correct float height adjustment is 12.0 mm
(0.472 in.) measured from the float bottom to the
body of the carburetor. See Figure 5-25. Adjust
the float height by carefully bending the metal
tang of the float.
Figure 5-23. Float and Inlet Needle.
Figure 5-25. Checking Float Height.
5.16
Section 5
Fuel System and Governor
14. When the proper float height is obtained,
carefully install the new O-Rings for the fuel
bowl and the accelerator pump transfer passage
(if so equipped). See Figure 5-26.
Figure 5-28. Installing Idle Fuel Adjusting Screw
and Spring.
Figure 5-26. Installing Fuel Bowl O-Rings.
15. Install the fuel bowl onto the carburetor. Secure
with the four original screws. Torque the screws
to 2.5 ± 0.3 N·m (23 ± 2.6 in. lb.). Reattach the
accelerator pump hose (if so equipped), and
secure with the clip. See Figure 5-27.
18. Place the shorter new spring onto the idle speed
adjusting screw and install it into the carburetor.
Thread in until 3 or 4 threads are exposed, as an
initial adjustment. See Figure 5-29.
Figure 5-29. Installing Idle Speed Adjusting Screw
and Spring.
Figure 5-27. Installing Fuel Bowl.
16. Install the new cover gasket and top cover on the
carburetor. Secure with the two large-head screws
and attach the ground lead (if equipped with a
fuel solenoid), to the original screw location.
Torque the top cover screws to 2.5 ± 0.3 N·m
(23 ± 2.6 in. lb.).
17. Place the longer new spring onto the idle fuel
adjusting screw and install it into the carburetor.
As an initial adjustment, set to 1 turn out from
lightly seated. See Figure 5-28.
Accelerator Pump Rebuild
NOTE: Access to the accelerator pump can be
limited, due to specific engine options or the
application. Although installation of the kit is
possible with the carburetor intact, removal is
normally necessary and recommended. These
instructions cover installation of the kit
components only. If needed, instructions for
removal and reinstallation of the carburetor
can be found in Sections 9 and 11
respectively.
1. Remove the vacuum hose from the accelerator
pump cover and the carburetor flange fitting.
5.17
5
Section 5
Fuel System and Governor
2. Remove the three screws securing the cover to the
accelerator pump housing. Remove the cover,
spring, and diaphragm. See Figure 5-30.
Figure 5-32. Check Valve and Retaining Ring
Installed.
Figure 5-30. Accelerator Pump Cover and
Diaphragm Removed.
3. Remove the retaining ring over the rubber check
valve, using a snap ring pliers. Remove the check
valve from the fuel delivery chamber. See Figure
5-31.
Figure 5-31. Removing Retaining Ring.
4. Clean the accelerator pump housing and cover as
required.
5. Install the new check valve into the fuel delivery
chamber. Secure with the new retaining ring. See
Figure 5-32.
5.18
6. Notice the small alignment tab and the small
bead on one side of the outer diameter of the new
diaphragm. Install the diaphragm into the
housing, so the alignment tab is in the small
notch, the bead is down in the recessed channel,
and the “donut” around the metal center plate
should be out, facing you. See Figure 5-33.
Figure 5-33. Diaphragm Installed.
7. Install the new diaphragm spring and reinstall
the accelerator pump cover. Secure with the three
new screws. Torque the screws to 2.0 ± 0.6 N·m
(18.2 ± 5.2 in. lb.). See Figure 5-34.
Section 5
Fuel System and Governor
5. Use a screw extractor (easy out) and remove the
original choke shaft bushing with the old choke
lever from the carburetor housing. Save the
bushing to use as a driver for installing the new
bushing. Discard the old lever.
6. Clean the I.D. of both choke shaft bores as
required.
Figure 5-34. Installing Accelerator Pump Housing
Screws and Hose.
7. Insert the new bushing through the new choke
lever from the outside, and start the bushing in
the outer shaft bore. Position the choke lever so
that the protruding boss on the carburetor
housing is between the two stops formed in the
choke lever. See Figure 5-36.
5
8. Install the new clips onto each end of the new
vacuum hose, and connect the hose onto the
fittings. See Figure 5-34. Discard all the old parts.
Choke Repair
1. Remove the carburetor from the engine. Discard
the old mounting gaskets for the air cleaner and
carburetor.
2. Clean the areas around the choke shaft and the
self-relieving choke mechanism thoroughly.
3. Remove and discard the plastic cap from the end
of the choke lever/shaft assembly.
4. Note the position of the spring legs and the choke
plate for correct reassembly later. See Figure
5-35. Remove the two screws attaching the choke
plate to the choke shaft. Pull the shaft out of the
carburetor body and discard the removed parts.
Figure 5-35. Choke Details.
Figure 5-36. Assembling Choke Lever.
8. Turn the old bushing upside down and use it as a
driver to carefully press or tap the new bushing
into the carburetor body until it bottoms. Check
that the choke lever pivots freely without
restriction or binding. See Figure 5-37.
Figure 5-37. Installing Bushing.
5.19
Section 5
Fuel System and Governor
9. Install the new return spring onto the new choke
shaft, so the upper leg of the spring is between
the two formed “stops” on the end of the choke
shaft. See Figure 5-38. Note: Make sure it stays in
this location during the following step.
Figure 5-38. Choke Shaft and Spring Details.
10. Slide the choke shaft and spring, into the
carburetor. Pivot (preload) the shaft and set the
inner leg of the spring, against the formed stop
within the choke lever as originally assembled.
See Figure 5-35. The opposing leg of the spring
must still be between the formed “stops” of the
choke shaft.
11. Place a drop of the Loctite® on the threads of each
new screw. Install the new choke plate to the flat
side of the choke shaft and start the two screws.
The larger cutout must be on the right. Close the
choke and check the plate alignment within the
carburetor throat, then tighten the screws
securely. Do not overtighten.
12. Check for proper operation and free movement of
the parts. Install the new cap.
Always use new gaskets when servicing or reinstalling
carburetors. Repair kits are available which include
new gaskets and other components. Service/repair kits
available for Keihin carburetors and affiliated
components are:
Carburetor Repair Kit
Float Kit
Solenoid Assembly Kit
Accelerator Pump Kit
Choke Repair Kit
High Altitude Kit (1525-3048 m/5,000-10,000 ft.)
High Altitude Kit (Over 3048 m/10,000 ft.)
5.20
Carburetor
Keihin BK Two-Barrel Carburetor (CV750)
The carburetor used on CV750 engines is a Keihin
two-barrel side draft design with fixed main jets. See
Figure 5-39. A self-relieving choke similar to that used
on single venturi carburetors is also contained in the
design. The circuits within the carburetor function as
described following:
Float Circuit:
The fuel level in the bowl is maintained by the float
and fuel inlet needle. The buoyant force of the float
stops fuel flow when the engine is at rest. When fuel is
being consumed, the float will drop and fuel pressure
will push the inlet needle away from the seat,
allowing more fuel to enter the bowl. When demand
ceases, the buoyant force of the float will again
overcome the fuel pressure, rising to the
predetermined setting and stop the flow.
Slow & Mid-Range Circuit:
At low speeds the engine operates only on the slow
circuit. As a metered amount of air is drawn through
the slow air bleed jets, fuel is drawn through the two
main jets and further metered through the slow jets.
Air and fuel are mixed in the body of the slow jet and
exit to the transfer port. From the transfer port the air
fuel mixture is delivered to the idle progression
chamber. From the idle progression chamber the air
fuel mixture is metered through the idle port
passages. At low idle when the vacuum signal is weak,
the air/fuel mixture is controlled by the setting of the
idle fuel adjusting screws. This mixture is then mixed
with the main body of air and delivered to the engine.
As the throttle plate opening increases, greater
amounts of air/fuel mixture are drawn in through the
fixed and metered idle progression holes. As the
throttle plate opens further the vacuum signal
becomes great enough so the main circuit begins to
work.
Main (High-Speed) Circuit:
At high speeds/loads the engine operates on the main
circuit. As a metered amount of air is drawn through
the four air jets, fuel is drawn through the main jets.
The air and fuel are mixed in the main nozzles and
then enter the main body of airflow, where further
mixing of the fuel and air occurs. This mixture is then
delivered to the combustion chamber. The carburetor
has a fixed main circuit; no adjustment is possible.
Section 5
Fuel System and Governor
Adjustment
NOTE: Carburetor adjustments should be made only
after the engine has warmed up.
The carburetor is designed to deliver the correct fuelto-air mixture to the engine under all operating
conditions. The main fuel jet is calibrated at the
factory and is not adjustable*. The idle fuel adjusting
needle is also set at the factory and normally does not
need adjustment.
Depending on model and application, engines may
also be equipped with a “Governed Idle System.” If
equipped with a “Governed Idle System”, refer to
“Models with Governed Idle System” when
performing any carburetor adjustment, as an
additional step to the listed adjustment procedure(s) is
required.
*NOTE: The actual low idle speed depends on the
application. Refer to the equipment
manufacturer’s recommendations. The low
idle speed for basic engines is 1200 RPM. To
ensure best results when setting the low idle
fuel needle, the low idle speed should be
1200 RPM (± 75 RPM).
Low Idle Fuel Adjustment
NOTE: Engines will have fixed low idle or limiter
caps on the two idle fuel adjusting needles.
Step 3 can only be performed within the
limits allowed by the cap. Do not attempt to
remove the limiter caps.
1. Start the engine and run at half throttle for 5 to 10
minutes to warm up. The engine must be warm
before doing steps 2, 3, and 4.
*NOTE: Engines operating at altitudes above
approximately 1500 m (5000 ft.) may require
a special ‘‘high altitude’’ main jet. Refer to
‘‘High Altitude Operation’’.
2. Place the throttle control into the “idle” or
“slow” position. Adjust the low idle speed to
1200 RPM*. Follow the “Adjusting the Low Idle
Speed (RPM)” procedure.
If, however, the engine is hard-starting or does not
operate properly, it may be necessary to adjust or
service the carburetor.
3. Low Idle Fuel Needle(s) Setting: Place the
throttle into the “idle” or “slow” position.
Low Idle Fuel Adjusters
(with Limiters)
Low Idle Speed (RPM)
Adjustment Screw
Fuel Solenoid
a. Turn one of the low idle fuel adjusting needles
out (counterclockwise) from the preliminary
setting until the engine speed decreases
(rich). Note the position of the needle. Now
turn the adjusting needle in (clockwise). The
engine speed may increase, then it will
decrease as the needle is turned in (lean). Note
the position of the needle. Set the adjusting
needle midway between the rich and lean
settings. See Figure 5-40.
b. Repeat the procedure on the other low idle
adjustment needle.
Bowl Drain Screw
Figure 5-39. Keihin Two-Barrel Carburetor.
4. Recheck/adjust the Low Idle Speed (RPM), to the
specified setting.
Carburetor Adjustment
Low Idle Speed (RPM) Adjustment
1. Low Idle Speed (RPM) Setting: Place the throttle
control into the “idle” or “slow” position. Set the
low idle speed to 1200 RPM* (± 75 RPM) by
turning the low idle speed adjusting screw in or
out. Check the speed using a tachometer.
5.21
5
Section 5
Fuel System and Governor
Adjust to
Midpoint
Lean
Adjust to
Midpoint
Lean
Governed
Idle Spring
Tab
Rich
Rich
Left Side
Right Side
Figure 5-40. Optimum Low Idle Fuel Settings.
Figure 5-41. Governed Idle Spring Location.
Models with Governed Idle System
An optional governed idle control system is supplied
on some engines. The purpose of this system is to
maintain a desired idle speed regardless of ambient
conditions (temperature, parasitic load, etc.) that may
change. Engines with this feature contain a small
secondary spring connected between the governor
lever and the lower adjustment tab of the main
bracket. See Figure 5-41.
The system requires an additional procedure for
setting the idle speed. If speed adjustments are
required proceed as follows.
1. Make any necessary speed or control adjustments
following the appropriate instructions covered in
this section.
2. Move the throttle control to the idle position.
Hold the governor lever away from the
carburetor, or hold the throttle lever so it is tight
against the idle speed adjusting screw, to negate
the governor activation. See Figure 5-42. Check
the speed with a tachometer and adjust it to 1500
RPM.
3. Release the governor lever and allow the engine
to return to the governed idle speed. Check it
with a tachometer against the equipment
manufacturers recommended idle speed.
Governed Idle Speed (RPM) is typically 300 RPM
(approximate) higher than the low idle speed. If
adjustment is necessary, bend the adjusting tab on
the speed control assembly to set. See Figure 5-41.
5.22
Hold
Throttle
Lever
Against
Screw
Figure 5-42. Holding Throttle Lever Against Idle
Stop Screw (Two-Barrel Carburetor).
Carburetor Servicing
Float Replacement
If symptoms described in the carburetor
troubleshooting guide indicate float level problems,
remove the carburetor from the engine to check and/
or replace the float. Use a float kit to replace the float,
pin, float valve, clip and screw.
1. Perform the removal procedures for the Heavy
Duty Air Cleaner and Carburetor outlined in
Section 9 “Disassembly.”
2. Clean the exterior surfaces of dirt or foreign
material before disassembling the carburetor.
Remove the four mounting screws and carefully
separate the fuel bowl from the carburetor. Do
not damage the inner or bowl O-Ring. Transfer
any remaining fuel into an approved container.
Save all parts. Fuel can also be drained prior to
bowl removal by loosening/removal of the bowl
drain screw. See Figure 5-43.
Section 5
Fuel System and Governor
Fuel Bowl
Bowl Drain Screw
Figure 5-43. Fuel Bowl Removed From Carburetor.
3. Remove the float pin screw and lift out the old
float, pin and inlet needle. See Figure 5-44.
Discard all of the parts. The seat for the inlet
needle is not serviceable, and should not be
removed.
Figure 5-45. Float and Inlet Needle Details.
6. Install the float and inlet needle down into the
seat and carburetor body. Install the new pivot
pin through the float hinge and secure with the
new retaining screw. See Figure 5-46.
Figure 5-46. Installing Float Assembly.
Figure 5-44. Removing Float and Inlet Needle.
4. Clean the carburetor bowl and inlet seat areas as
required, before installing the new parts.
5. Attach the inlet needle to the plastic tang of the
float with the wire clip. The formed 90° lip
should point up, with the needle valve hanging
down. See Figure 5-45.
7. Hold the carburetor body so the float assembly
hangs vertically and rests lightly against the fuel
inlet needle. The inlet needle should be fully
seated but the center pin of the needle (on
retainer clip end) should not be depressed. Check
the float height adjustment.
NOTE: The inlet needle center pin is spring loaded.
Make sure the float rests against the fuel inlet
needle without depressing the center pin.
8. The correct float height setting is 17 mm
(0.669 in.) ± 1.5 mm (0.059 in.), measured from
the float bottom to the body of the carburetor. See
Figure 5-47. Replace the float if the height is
different than the specified setting. Do not
attempt to adjust by bending float tab.
5.23
5
Section 5
Fuel System and Governor
Fuel Bowl
Bowl Drain Screw
Figure 5-47. Checking Float Height.
NOTE: Be sure to measure from the casting
surface, not the rubber gasket, if still
attached.
9. When the proper float height is obtained,
carefully reinstall the fuel bowl, using new
O-Rings onto the carburetor. Secure with the four
original screws. Torque the screws to 2.5 ± 0.3
N·m (23 ± 2.6 in. lb.). See Figure 5-48.
Figure 5-48. Installing Fuel Bowl.
10. Install the carburetor and the heavy-duty air
cleaner as outlined in Section 11 “Reassembly.”
Disassembly/Overhaul
1. Clean the exterior surfaces of dirt or foreign
material before disassembling the carburetor.
Remove the four mounting screws and separate
the fuel bowl from the carburetor. Transfer any
remaining fuel into an approved container.
Remove and discard the old O-Rings. Fuel can
also be drained prior to bowl removal by
loosening/removal of the bowl drain screw. See
Figure 5-49.
5.24
Figure 5-49. Fuel Bowl Removed From Carburetor.
NOTE: Further disassembly of the fuel bowl is
not necessary unless the Fuel Solenoid
Kit, or Fuel Bowl Kit (obtained
separately), will also be installed.
2. Remove the float pin screw and lift out the old
float, pin, and inlet needle. See Figure 5-50.
Discard all the old parts. The seat for the inlet
needle is not serviceable, and should not be
removed.
Figure 5-50. Removing Float and Inlet Needle.
3. Use an appropriate size flat screwdriver, and
carefully remove the two main jets from the
carburetor. Note and mark the jets by location for
proper reassembly. The main jets may be size/side
specific. After the main jets are removed, the
main nozzles can be removed out through the
bottom of the main towers. Note the orientation/
direction of the nozzles. The end with the two
raised shoulders should be out/down adjacent to
the main jets. Save the parts for cleaning and
reuse. See Figure 5-51.
Section 5
Fuel System and Governor
Slow (Idle Fuel) Jets
Main Nozzles
O-Ring
Main Jets
Figure 5-51. Main Jets and Nozzles Removed.
4. Remove the screw securing the flat washer and
ground lead (if equipped), from the top of the
carburetor; then carefully pull (lift) out the two
slow jets. The slow jets may be size/side specific,
mark or tag for proper reassembly. Note the small
O-Ring on the bottom of each jet. See Figure 5-52
and 5-53. Save parts for cleaning and reuse unless
a Jet Kit is also being installed. Clean the slow jets
using compressed air. Do not use wire or
carburetor cleaner.
Figure 5-52. Removing Screw and Washer.
Figure 5-53. Slow Jets and O-Ring Detail.
5. Remove the idle speed (RPM) adjustment screw
and spring from the carburetor. Discard the parts.
NOTE: The carburetor is now disassembled for
appropriate cleaning and installation of the
parts in the overhaul kit. Further disassembly
is not necessary. The throttle shaft assembly,
fuel inlet seat, idle fuel adjustment screws
with limiter, and carburetor body, are nonserviceable items and should not be removed.
The choke shaft assembly is serviceable,
however it should not be removed unless a
Choke Repair Kit will be installed.
6. Clean the carburetor body, main jets, vent ports,
seats, etc. using a good commercially available
carburetor solvent. Keep away from plastic or
rubber parts if non-compatible. Use clean, dry
compressed air to blow out the internal channels
and ports. Do not use metal tools or wire to clean
orifices and jets. Inspect and thoroughly check
the carburetor for cracks, wear, or damage.
Inspect the fuel inlet seat for wear or damage.
Check the spring loaded choke plate to make sure
it moves freely on the shaft.
7. Clean the carburetor fuel bowl as required.
8. Install the two main nozzles into the towers of the
carburetor body. The end of the main nozzles
with the two raised shoulders should be out/
down (adjacent to the main jets). Make sure the
nozzles are completely bottomed. Carefully
install the main jets into the towers of the
carburetor body on the appropriate side, as
identified when removal was performed. See
Figure 5-54.
5.25
5
Section 5
Fuel System and Governor
Nozzle End with Two
Shoulders (Out/Down)
Main Jets
Figure 5-54. Installing Main Nozzles and Main Jets.
9. Make sure the O-Ring near the bottom of each
slow jet is new, or in good condition. Align and
insert the two slow jets into the top of carburetor.
See Figure 5-53.
Figure 5-56. Float and Inlet Needle Details.
13. Install the float and inlet needle down into the
seat and carburetor body. Install the new pivot
pinthrough the float hinge and secure with the
new retaining screw. See Figure 5-57.
10. Install the large flat retaining washer and secure
with the mounting screw, attaching the ground
lead if originally secured by the screw.
11. Install the new idle speed (RPM) adjustment
screw and spring onto the carburetor. Thread in
until 3 or 4 threads are exposed, as an initial
adjustment. See Figure 5-55.
Figure 5-57. Installing Float Assembly.
14. Hold the carburetor body so the float assembly
hangs vertically and rests lightly against the fuel
inlet needle. The inlet needle should be fully
seated but the center pin of the needle (on
retainer clip end) should not be depressed. Check
the float height adjustment.
Figure 5-55. Installing Idle Speed Adjusting Screw
and Spring.
12. Attach the inlet needle to the plastic tang of the
float with the wire clip. The formed 90° lip
should point up, with the needle valve hanging
down. See Figure 5-56.
5.26
NOTE: The inlet needle center pin is spring
loaded. Make sure the float rests against
the fuel inlet needle without depressing
the center pin.
15. The correct float height setting is 17 mm
(0.669 in.) ± 1.5 mm (0.059 in.), measured from
the float bottom to the body of the carburetor. See
Figure 5-58. Replace the float if the height is
different than the specified setting. Do not
attempt to adjust by bending float tab.
Section 5
Fuel System and Governor
4. Note the position of the spring legs and the choke
plate for correct reassembly later. See Figure
5-60. Remove the two screws attaching the choke
plate to the choke shaft. Pull the shaft out of the
carburetor body and discard the removed parts.
Figure 5-58. Checking Float Height.
NOTE: Be sure to measure from the casting surface,
not the rubber gasket, if still attached.
16. When the proper float height is obtained, carefully
reinstall the fuel bowl, using new O-Rings onto
the carburetor. Secure with the four original
screws. Torque the screws to 2.5 ± 0.3 N·m
(23 ± 2.6 in. lb.). See Figure 5-59.
5
Figure 5-60. Choke Details.
5. Use a screw extractor (easy-out) and remove the
original choke shaft bushing with the old choke
lever from the carburetor housing. Save the
bushing to use as a driver for installing the new
bushing. Discard the old lever.
6. Clean the I.D. of both choke shaft bores as
required.
7. Insert the new bushing through the new choke
lever from the outside, and start the bushing in
the outer shaft bore. Position the choke lever so
the protruding boss on the carburetor housing is
between the two stops formed in the choke lever.
See Figure 5-61.
Figure 5-59. Installing Fuel Bowl.
Choke Repair
1. Remove the carburetor from the engine. Discard
the old mounting gaskets for the air cleaner and
carburetor.
Stops
2. Clean the areas around the choke shaft and the
self-relieving choke mechanism thoroughly.
3. Remove and discard the plastic cap from the end
of the choke lever/shaft assembly.
Boss
Figure 5-61. Assembling Choke Lever.
5.27
Section 5
Fuel System and Governor
8. Turn the old bushing upside down and use it as a
driver to carefully press or tap the new bushing
into the carburetor body until it bottoms. Check
that the choke lever pivots freely without
restriction or binding. See Figure 5-62.
11. Place a drop of Loctite® on the threads of each
new screw. Position and install the new choke
plate to the flat side of the choke shaft. Start the
two screws. Close the choke and check the plate
alignment within the carburetor throat, then
tighten the screws securely. Do not overtighten.
See Figure 5-64.
Figure 5-62. Installing Bushing.
9. Install the new return spring onto the new choke
shaft, so the upper leg of the spring is between
the two formed “stops” on the end of the choke
shaft. See Figure 5-63.
NOTE: Make sure it stays in this location during
the following step.
Figure 5-64. Installing Choke Plate.
12. Check for proper operation and free movement of
the parts. Install the new cap.
Always use new gaskets when servicing or reinstalling
carburetors. Repair kits are available which include
new gaskets and other components. Service/repair kits
available for Keihin BK two-barrel carburetors and
affiliated components are:
Carburetor Overhaul Kit
Float Kit
Fuel Solenoid Kit
Choke Repair Kit
Bowl Kit
High Altitude Kit (1525-3048 m/5,000-10,000 ft.)
High Altitude Kit (Over 3048 m/10,000 ft.)
Figure 5-63. Choke Shaft and Spring Details.
10. Slide the choke shaft and spring into the
carburetor. Pivot (preload) the shaft and set the
inner leg of the spring, against the formed stop
within the choke lever as originally assembled.
See Figure 5-60. The opposing leg of the spring
must still be between the formed “stops” of the
choke shaft.
5.28
Section 5
Fuel System and Governor
4
5
8
7
6
9
9
2
32
3
31
1
30
29
28
21
20
27
17
26
22
23
18
24
25
19
11
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
Carburetor Body Subassembly
Idle Speed Screw
Idle Speed Spring
Screw
Ground Lead
Retaining Washer
Slow Jet - RH Side
Slow Jet - LH Side
O-Ring (Slow Jet) (2)
Fuel Bowl
O-Ring (Fuel Bowl - Upper)
O-Ring (Fuel Bowl - Lower)
Drain Screw
Bowl Screw (4)
Fuel Solenoid
Sealing Washer
Float
Pin
Screw
Float Clip
Float Valve/Inlet Needle
Main Nozzle - Right Side
Main Nozzle - Left Side
Main Jet - Right Side
Main Jet - Left Side
Choke Dust Cap
Choke Shaft
Spring
Bushing
Choke Lever
Choke Plate
Choke Plate Screw (2)
12
10
14
13
16
15
Figure 5-65. Keihin BK Two-Barrel Carburetor - Exploded View.
5.29
5
Section 5
Fuel System and Governor
Governor
Adjustments
General
The engine is equipped with a centrifugal flyweight
mechanical governor. It is designed to hold the engine
speed constant under changing load conditions. The
governor gear/flyweight mechanism is mounted
inside the crankcase on the oil pan, and is driven off
the gear on the camshaft. The governor works as
follows:
General
The governed speed setting is determined by the
position of the throttle control. It can be variable or
constant, depending on the engine application.
•
Centrifugal force acting on the rotating governor
gear assembly causes the flyweights to move
outward as speed increases. Governor spring
tension moves them inward as speed decreases.
•
As the flyweights move outward, they cause the
regulating pin to move outward.
•
•
•
The regulating pin contacts the tab on the cross
shaft causing the shaft to rotate. One end of the
cross shaft protrudes through the crankcase. The
rotating action of the cross shaft is transmitted to
the throttle lever of the carburetor through the
external linkage. See Figure 5-66.
When the engine is at rest, and the throttle is in
the “fast” position, the tension of the governor
spring holds the throttle plate open. When the
engine is operating, the governor gear assembly
is rotating. The force applied by the regulating
pin against the cross shaft tends to close the
throttle plate. The governor spring tension and
the force applied by the regulating pin balance
each other during operation, to maintain engine
speed.
When load is applied and the engine speed and
governor gear speed decreases, the governor
spring tension moves the governor lever to open
the throttle plate wider. This allows more fuel
into the engine, increasing engine speed. As
speed reaches the governed setting, the governor
spring tension and the force applied by the
regulating pin will again offset each other to hold
a steady engine speed.
Hex
Nut
Cross Shaft
Governor
Arm
Governor Spring
Figure 5-66. Governor Controls and Linkage
(External).
Initial Adjustment
NOTE: EFI engines require a special initial
adjustment procedure, which is covered in
subsection 5B. Refer to “Initial Governor
Adjustment” in that section for setting the
governor on EFI-equipped engines.
Procedure - Carburetor Equipped Engines
Make this adjustment whenever the governor arm is
loosened or removed from the cross shaft. See Figure
5-66 and adjust as follows:
1. Make sure the throttle linkage is connected to the
governor lever and the throttle lever on the
carburetor.
2. Loosen the hex nut holding the governor lever to
the cross shaft.
3. Move the governor lever toward the carburetor
as far as it will move (wide-open throttle) and
hold in position.
4. Insert a nail into the hole in the end of the cross
shaft and rotate the shaft counterclockwise as far
as it will turn, then tighten the hex nut securely.
5.30
Section 5
Fuel System and Governor
Sensitivity Adjustment
Governor sensitivity is adjusted by repositioning the
governor spring in the holes of the governor lever. If
speed surging occurs with a change in engine load, the
governor is set too sensitive. If a big drop in speed
occurs when normal load is applied, the governor
should be set for greater sensitivity. See Figure 5-66
and adjust as follows:
1. To increase the sensitivity, move the spring closer
to the governor lever pivot point.
2. To decrease the sensitivity, move the spring away
from the governor lever pivot point.
High Speed (RPM) Adjustment (Refer to Figures
5-67, 5-68, or 5-69.)
1. With the engine running, move the throttle
control to fast. Use a tachometer to check the
RPM speed.
2. Loosen the lock nut on the high speed adjusting
screw. Turn the screw counterclockwise to
decrease, or clockwise to increase RPM speed.
Check RPM with a tachometer.
3. When the desired RPM speed is obtained,
retighten the lock nut.
NOTE: When the throttle and choke control cables
are routed side-by-side, especially under a
single clamp, there must be a small gap
between the cables to prevent internal
binding. After the high-speed setting has
been completed, check that there is a gap of
at least 0.5 mm (0.020 in.) between the control
cables.
Throttle Control
Lever #2
Left Side Pull
Choke
Control
Cable
Choke Control
Lever #1
Kill Switch
Choke Linkage
Z Bend
Throttle
Control
Cable
Throttle
Control Cable
Kill Switch
Adjusting Screw
Dual Control High
Speed Lever Stop
Screw "Do Not
High Speed
Remove"
Adjusting
Screw
Choke
Control
Cable
High Speed
Control Lever
Right Side Pull
Figure 5-67. Governor Control Connections.
5.31
5
Section 5
Fuel System and Governor
Choke Lever
Choke Lever Detail
Screw
Spring
Washer
Spacer
Washer
Lock
Nut
Bushing
Fastener
Choke Lever
(See Detail at Left)
Screw and Nut
Choke Cable
Control
Bracket
Linkage
Control Lever
Fastener
Lock Nut
Throttle
Cable
Clamp
Blower Housing
Washer
Spring
Fuel
Pump
Clamp
Clip
Bushing
Fuel Line
Spring
Linkage
Bushing
Throttle Shaft
Bracket
Lever
Spring
Washer
Locker Nut
Spacer
Throttle Lever
Deflector
(If So Equipped)
(Place Between Valley
Baffle and Throttle
Shaft Bracket)
Figure 5-68. Governor Used with Commercial Mower Air Cleaner (CV17-745).
Commercial Mower Governor
Arrangement
The Commercial Mower governor arrangement shown
in Figure 5-68 is used primarily on wide area walk
behind mower applications. The initial adjustment
and sensitivity adjustment is the same as for the
standard governor. The governor and controls for the
CV750 engine is shown in Figure 5-69. Should the
governor spring be disconnected from the throttle
lever and governor lever, reconnect it as follows:
5.32
1. Hook the long end of the spring through the hole
in the lever from the left side.
2. Rotate the spring 180° until hooked as shown in
Figure 5-69.
3. Hook the short end of the spring into the
appropriate hole in the governor lever. Refer to
the appropriate chart in Section 11 - "Reassembly"
of this manual for the correct hole to use for the
speed involved.
Section 5
Fuel System and Governor
Screw
Washer
Lock Nut
Spring
Washer
Spacer
Bushing
Choke Linkage
Hex Nut Screw
Choke
Cable
Throttle Control Lever
Clamp
and Screw
5
Lock Nut
Control
Bracket
Screw
Washer
Spring
Throttle
Cable
Throttle Linkage
Fuel Pump
Bushing
Linkage Spring
Clamp
Fuel
Throttle Shaft
Bushing
Throttle Shaft Bracket
Governor Lever
Governor Spring
Washer
Spacer
Lock Nut
Throttle Lever
Deflector (If
So Equipped)
Figure 5-69. Governor/Controls Assembly (CV750).
5.33
Section 5B
EFI Fuel System
Section 5B
Electronic Fuel Injection (EFI)
Fuel System
Contents
Page(s)
Description
Initial Starting/Priming Procedure ......................................................................................................................... 5B.2
Fuel Recommendations ................................................................................................................................... 5B.2-5B.3
EFI Fuel System Components ................................................................................................................................. 5B.3
Operation ................................................................................................................................................................... 5B.3
Important Service Notes .......................................................................................................................................... 5B.4
Electrical Components
Electronic Control Unit (ECU) ....................................................................................................................... 5B.4-5B.5
Engine Speed Sensor ....................................................................................................................................... 5B.5-5B.6
Throttle Position Sensor (TPS) and Initialization Procedures ................................................................... 5B.6-5B.9
Engine (Oil) Temperature Sensor ................................................................................................................ 5B.9-5B.10
Oxygen Sensor .............................................................................................................................................. 5B.10-5B.12
Electrical Relay ............................................................................................................................................. 5B.12-5B.13
Fuel Injectors ................................................................................................................................................ 5B.13-5B.16
Ignition System .......................................................................................................................................................5B.17
Spark Plugs ..............................................................................................................................................................5B.18
Wiring Harness .......................................................................................................................................................5B.18
Battery Charging System ....................................................................................................................................... 5B.18
Fuel Components
Fuel Pump ..................................................................................................................................................... 5B.18-5B.19
Fuel Pressure Regulator .............................................................................................................................. 5B.19-5B.21
Fuel Filter ................................................................................................................................................................. 5B.21
Fuel Rail ...................................................................................................................................................................5B.21
Fuel Line ........................................................................................................................................................ 5B.21-5B.22
Throttle Body/Intake Manifold Assembly .......................................................................................................... 5B.22
Idle Speed Adjustment (RPM) ................................................................................................................... 5B.22-5B.23
Initial Governor Adjustment ...................................................................................................................... 5B.23-5B.25
Troubleshooting
Troubleshooting Guide .......................................................................................................................................... 5B.25
Electrical System .......................................................................................................................................... 5B.25-5B.29
Fuel System ..............................................................................................................................................................5B.30
Fault Codes ................................................................................................................................................... 5B.30-5B.38
Troubleshooting Flow Chart ...................................................................................................................... 5B.38-5B.39
Flow Chart Diagnostic Aids ....................................................................................................................... 5B.40-5B.41
EFI Service Tools ............................................................................................................................... Refer to Section 2
5B.1
5B
Section 5B
EFI Fuel System
Description
WARNING
2. For plastic-cased ECU’s below 24 584 28-S, the
system can be primed by manually cycling the
fuel pump.
a. Turn the key switch to the “on/run” position.
The fuel pump will run for about three
seconds and stop. Turn the switch off and
back on to restart the fuel pump. Repeat
this procedure until the fuel pump has
cycled five times, then start the engine.
Explosive Fuel can cause fires and
severe burns.
Fuel system ALWAYS remains under
HIGH PRESSURE.
WARNING: Explosive Fuel!
Gasoline is extremely flammable and its vapors can explode
if ignited. Store gasoline only in approved containers, in
well ventilated, unoccupied buildings, away from sparks or
flames. Do not fill the fuel tank while the engine is hot or
running, since spilled fuel could ignite if it comes in contact
with hot parts or sparks from ignition. Do not start the
engine near spilled fuel. Never use gasoline as a cleaning
agent.
The EFI fuel system remains under high pressure even
when the engine is stopped. Before attempting to service
any part of the fuel system, the pressure must be relieved.
Pressure tester, (part of EFI Service Kit, see Section 2) has
an integral relief valve. Connect the black tester hose to the
test valve in the fuel rail. Route the clear hose into a
portable gasoline container. Depress the button on the tester
relief valve.
Initial Starting/Priming Procedure
Important: The EFI fuel system must be purged of air
(primed) prior to the initial start up, and/or any time
the system has been disassembled or the fuel tank run
dry.
1. Locate the electronic control unit (ECU) for the
EFI system. Check the part number on the end. If
the Part No. is 24 584 28 or higher, the ECU has a
built-in priming feature.
a. Turn the key switch to the “on/run” position.
You will hear the fuel pump cycle on and off.
When the fuel pump stops cycling
(approximately one minute), the system is
primed; start the engine.
5B.2
3. The system can also be primed similar to
relieving pressure.
a. Connect the pressure gauge as described
above for relieving fuel pressure. Depress
and hold the release button and crank the
engine until the air is purged and fuel is
visible in the discharge tube. If fuel is not
visible after 10 seconds, stop cranking and
allow the starter to cool for 60 seconds.
Fuel Recommendations
General Recommendations
Purchase gasoline in small quantities and store in
clean, approved containers. An approved container
with a capacity of 2 gallons or less with a pouring
spout is recommended. Such a container is easier to
handle and helps prevent spillage during refueling.
•
Do not use gasoline left over from the previous
season, to minimize gum deposits in your fuel
system, and to ensure easy starting.
•
Do not add oil to the gasoline.
•
Do not overfill the fuel tank. Leave room for the
fuel to expand.
Fuel Type
Do not use leaded gasoline, as component damage
will result. Any costs/damages incurred as a result of
using leaded fuel will not be warranted. Use only
clean, fresh, unleaded gasoline with a pump sticker
octane rating of 87 or higher. In countries using the
Research method, it should be 90 octane minimum.
Section 5B
EFI Fuel System
Gasoline/Alcohol blends
Gasohol (up to 10% ethyl alcohol, 90% unleaded
gasoline by volume) is approved as a fuel for Kohler
EFI engines. Other gasoline/alcohol blends are not
approved.
Gasoline/Ether blends
Methyl Tertiary Butyl Ether (MTBE) and unleaded
gasoline blends (up to a maximum of 15% MTBE by
volume) are approved as a fuel for Kohler EFI engines.
Other gasoline/ether blends are not approved.
EFI Fuel System Components
General
The Electronic Fuel Injection (EFI) system is a
complete engine fuel and ignition management
design. The system includes the following principal
components:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fuel Pump
Fuel Filter
Fuel Rail
Fuel Line(s)
Fuel Pressure Regulator
Fuel Injectors
Throttle Body/Intake Manifold
Engine Control Unit (ECU)
Ignition Coils
Engine (Oil) Temperature Sensor
Throttle Position Sensor (TPS)
Speed Sensor
Oxygen Sensor
Wire Harness Assembly & Affiliated Wiring,
Malfunction Indicator Light (MIL)
Operation
The EFI system is designed to provide peak engine
performance with optimum fuel efficiency and lowest
possible emissions. The ignition and injection
functions are electronically controlled, monitored and
continually corrected during operation to maintain the
theoretical ideal or “stoichiometric” air/fuel ratio of
14.7:1.
The central component of the system is the Motronic™
Engine Control Unit (ECU) which manages system
operation, determining the best combination of fuel
mixture and ignition timing for the current operating
conditions.
An electric fuel pump is used to move fuel from the
tank through the fuel line and in-line fuel filter. A fuel
pressure regulator maintains a system operating
pressure of 39 psi and returns any excess fuel to the
tank. At the engine, fuel is fed through the fuel rail
and into the injectors, which inject it into the intake
ports. The ECU controls the amount of fuel by varying
the length of time that the injectors are “on.” This can
range from 1.5-8.0 milliseconds depending on fuel
requirements. The controlled injection of the fuel
occurs each crankshaft revolution, or twice for each 4stroke cycle. One-half the total amount of fuel needed
for one firing of a cylinder is injected during each
injection. When the intake valve opens, the fuel/air
mixture is drawn into the combustion chamber,
ignited, and burned.
The ECU controls the amount of fuel being injected
and the ignition timing by monitoring the primary
sensor signals for engine temperature, speed (RPM),
and throttle position (load). These primary signals are
compared to preprogrammed “maps” in the ECU
computer chip, and the ECU adjusts the fuel delivery
to match the mapped values. After the engine reached
operating temperature, an exhaust gas oxygen sensor
provides feedback to the ECU based upon the amount
of unused oxygen in the exhaust, indicating whether
the fuel mixture being delivered is rich or lean. Based
upon this feedback, the ECU further adjusts fuel input
to re-establish the ideal air/fuel ratio. This operating
mode is referred to as “closed loop” operation. The
EFI system operates “closed loop” when all three of
the following conditions are met:
a. The oil temperature is greater than 35°C (86°F).
b. The oxygen sensor has warmed sufficiently to
provide a signal (minimum 375°C, 709°F).
c. Engine operation is at a steady state (not starting,
warming up, accelerating, etc.).
During “closed loop” operation the ECU has the
ability to readjust temporary and learned adaptive
controls, providing compensation for changes in
overall engine condition and operating environment,
so it will be able to maintain the ideal air/fuel ratio of
14.7:1. The system requires a minimum engine oil
temperature greater than 55°C (130°F) to properly
adapt. These adaptive values are maintained as long
as the ECU is “powered up” by the battery.
5B.3
5B
Section 5B
EFI Fuel System
During certain operating periods such as cold starts,
warm up, acceleration, etc., an air/fuel ratio richer
than 14.7:1 is required and the system operates in an
“open loop” mode. In “open loop” operation the
oxygen sensor output is not used, and the controlling
adjustments are based on the primary sensor signals
and programmed maps only. The system operates
“open loop” whenever the three conditions for closed
loop operation (above) are not being met.
•
Never use a quick battery charger to start the
engine.
•
Do not charge the battery with the key switch
‘‘on.’’
•
Always disconnect the negative (-) battery cable
before charging the battery, and also unplug the
harness from the ECU before performing any
welding on the equipment.
Important Service Notes!
•
Cleanliness is essential and must be maintained
at all times when servicing or working on the EFI
system. Dirt, even in small quantities, can cause
significant problems.
•
Clean any joint or fitting with parts cleaning
solvent before opening to prevent dirt from
entering the system.
•
Always depressurize the fuel system through the
test valve in the fuel rail before disconnecting or
servicing any fuel system components. See fuel
warning on page 5B.2.
•
Never attempt to service any fuel system
component while the engine is running or the
ignition switch is "on".
•
Do not use compressed air if the system is open.
Cover any parts removed and wrap any open
joints with plastic if they will remain open for
any length of time. New parts should be removed
from their protective packaging just prior to
installation.
•
Avoid direct water or spray contact with system
components.
•
Do not disconnect or reconnect the main ECU
wiring harness connector or any individual
components with the ignition ‘‘on.’’ This can send
a damaging voltage spike through the ECU.
•
Do not allow the battery cables to touch opposing
terminals. When connecting battery cables attach
the positive (+) cable to the positive (+) battery
terminal first, followed by the negative (-) cable to
the negative (-) battery terminal.
•
Never start the engine when the cables are loose
or poorly connected to the battery terminals.
•
Never disconnect the battery while the engine is
running.
5B.4
Electrical Components
Electronic Control Unit (ECU)
Figure 5B-1. “24 Pin” (MSE 1.0) Plastic-Cased ECU.
Figure 5B-2. “32 Pin” (MSE 1.1) Plastic-Cased ECU.
Section 5B
EFI Fuel System
Two different ECU styles have been used in CV EFI
production. Each has a plastic case, but they differ in
having a 24 pin or 32 pin connector block, and are
identified as MSE 1.0 or MSE 1.1 respectively. See
Figures 5B-1 and 5B-2. Basic function and operating
control remains the same between the two, however
due to differences in the internal circuitry as well as
the wiring harness, the ECU’s are not interchangeable.
Certain service/troubleshooting procedures will also
differ, so where applicable, they are covered
individually as: “24 Pin” (MSE 1.0) Plastic-Cased
ECU, or “32 Pin” (MSE 1.1) Plastic-Cased ECU.
To prevent engine over-speed and possible failure, a
“rev-limiting” feature is programmed into the ECU. If
the maximum RPM limit (4500) is exceeded, the ECU
suppresses the injection signals, cutting off the fuel
flow. This process repeats itself in rapid succession,
limiting operation to the preset maximum.
General
The ECU is the brain or central processing computer
of the entire EFI system. During operation, sensors
continuously gather data which is relayed through the
wiring harness to input circuits within the ECU.
Signals to the ECU include: ignition (on/off),
crankshaft position and speed (RPM), throttle
position, oil temperature, exhaust oxygen levels, and
battery voltage. The ECU compares the input signals
to the programmed maps in its memory to determine
the appropriate fuel and spark requirements for the
immediate operating conditions. The ECU then sends
output signals to set the injector duration and ignition
timing.
All operating and control functions within the ECU
are preset. No internal servicing or readjustment may
be performed. If a problem is encountered, and you
determine the ECU to be faulty, contact your source of
supply. Do not replace the ECU without factory
authorization.
The ECU continually performs a diagnostic check of
itself, each of the sensors, and the system
performance. If a fault is detected, the ECU turns on
the Malfunction Indicator Light (MIL) on the
equipment control panel, stores the fault code in its
fault memory, and goes into a default operating mode.
Depending on the significance or severity of the fault,
normal operation may continue, or “limp home”
operation (slowed speed, richer running) may be
initiated. A technician can access the stored fault code
using a “blink code” diagnosis flashed out through the
MIL. An optional computer software diagnostic
program is also available, see Section 2.
Engine Speed Sensor
The ECU requires a minimum of 7.0 volts to operate.
The adaptive memory in the ECU is operational
whenever the required voltage is present, however the
adapted values are lost if the power supply is
disrupted for any reason. The ECU will “relearn” the
adapted values if the engine is operated for 10-15
minutes at varying speeds and loads after the oil
temperature exceeds 55°C (130°F).
Service
Never attempt to disassemble the ECU. It is sealed to
prevent damage to internal components. Warranty is
void if the case is opened or tampered with in any
way.
The relationship between the ECU and the throttle
position sensor (TPS) is very critical to proper system
operation. If the TPS or ECU is changed, or the
mounting position of the TPS is altered, the
appropriate “TPS Initialization Procedure” (see pages
5B.8 and 5B.9) must be performed to restore the
synchronization.
Figure 5B-3. Engine Speed Sensor.
5B.5
5B
Section 5B
EFI Fuel System
General
The engine speed sensor is essential to engine
operation; constantly monitoring the rotational speed
(RPM) of the crankshaft. A ferromagnetic 60-tooth ring
gear with two consecutive teeth missing is mounted
on the flywheel. The inductive speed sensor is
mounted 1.5 ± 0.25 mm (0.059 ± 0.010 in.) away from
the ring gear. During rotation, an AC voltage pulse is
created within the sensor for each passing tooth. The
ECU calculates engine speed from the time interval
between the consecutive pulses. The two-tooth gap
creates an interrupted input signal, corresponding to
specific crankshaft position (84° BTDC) for cylinder
#1. This signal serves as a reference for the control of
ignition timing by the ECU. Synchronization of the
inductive speed pickup and crankshaft position takes
place during the first two revolutions each time the
engine is started. The sensor must be properly
connected at all times. If the sensor becomes
disconnected for any reason, the engine will quit
running.
Service
The engine speed sensor is a sealed, non-serviceable
assembly. If “Fault Code” diagnosis indicates a
problem within this area, test and correct as follows.
1. Check the mounting and air gap of the sensor. It
must be 1.5 mm ± 0.25 mm (0.059 ± 0.010 in.).
Dual Aligning Rails
Corresponds To
#9 Pin Terminal In
Main Connector
Corresponds
To #10 Pin
Terminal In Main
Connector
Test Terminals
Figure 5B-4. Speed Sensor Connector.
7. a. If the resistance is incorrect, remove the screw
securing the sensor to the mounting
bracket and replace the sensor.
b. If the resistance in step 5 was incorrect, but
the resistance of the sensor alone was correct,
test the main harness circuits between the
sensor connector terminals and the
corresponding pin terminals (#9 and #10) in
the main connector. Correct any observed
problem, reconnect the sensor, and perform
step 5 again.
Throttle Position Sensor (TPS)
2. Inspect the wiring and connections for damage or
problems.
3. Make sure the engine has resistor type spark
plugs.
4. Disconnect the main harness connector from the
ECU.
1 2
3
5. Connect an ohmmeter between the #9 and #10 pin
terminals.
See chart on page 5B.26 or 5B.29, according to
ECU style. A resistance value of 750-1000 Ω at
room temperature (20°C, 68°F) should be
obtained. If resistance is correct, check the
mounting, air gap, toothed ring gear (damage,
run-out, etc.), and flywheel key.
4
6. Disconnect the speed sensor connector from the
wiring harness. It is the connector with one heavy
black lead (see Figure 5B-4). Viewing the
connector as shown (dual aligning rails on top),
test resistance between the terminals indicated. A
reading of 750-1000 Ω should again be obtained.
5B.6
1. Throttle Valve Shaft
2. Resistor Track
3. Wiper Arm With Wiper
4. Electrical Connection
Figure 5B-5. Throttle Position Sensor Details.
Section 5B
EFI Fuel System
General
The throttle position sensor (TPS) is used to indicate
throttle plate angle to the ECU. Since the throttle (by
way of the governor) reacts to engine load, the angle
of the throttle plate is directly related to the load on
the engine.
3. a. Use an ohmmeter and connect the ohmmeter
leads as follows to test: (See chart on page
5B.26 or 5B.29.).
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Red
(positive) ohmmeter lead to #8 pin terminal, and
Black (negative) ohmmeter lead to #4 pin
terminal.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Red
(positive) ohmmeter lead to #8 pin terminal, and
Black (negative) ohmmeter lead to #4 pin
terminal.
b. Hold the throttle closed and check the
resistance. It should be 800-1200 Ω.
Figure 5B-6. TPS Location.
Mounted on the throttle body/intake manifold and
operated directly off the end of the throttle shaft, the
TPS works like a rheostat, varying the voltage signal
to the ECU in direct correlation to the angle of the
throttle plate. This signal, along with the other sensor
signals, is processed by the ECU and compared to the
internal pre-programmed maps to determine the
required fuel and ignition settings for the amount of
load.
The correct position of the TPS is established and set
at the factory. Do not loosen the TPS or alter the
mounting position unless absolutely required by fault
code diagnosis or throttle shaft service. If the TPS is
loosened or repositioned, the appropriate “TPS
Initialization Procedure must be performed to
reestablish the baseline relationship between the ECU
and the TPS.
Service
The TPS is a sealed, non-serviceable assembly. If
diagnosis indicates a bad sensor, complete
replacement is necessary. If a blink code indicates a
problem with the TPS, it can be tested as follows:
1. Counting the number of turns, back out the idle
speed adjusting screw (counterclockwise) until
the throttle plates can be closed completely.
2. Disconnect the main harness connector from the
ECU, but leave the TPS mounted to the throttle
body/manifold.
4. Leave the leads connected to the pin terminals as
described in step 3. Rotate the throttle shaft
slowly counterclockwise to the full throttle
position. Monitor the dial during rotation for
indication of any momentary short or open
circuits. Note the resistance at the full throttle
position. It should be 1800-3000 Ω.
5. Disconnect the main wiring harness connector
from the TPS, leaving the TPS assembled to the
manifold. Refer to the chart below and perform
the resistance checks indicated between the
terminals in the TPS switch, with the throttle in
the positions specified.
Throttle Between
Position Terminals
2&3
Closed
1&3
C losed
2&3
Full
1&3
Full
1&2
Any
Resistance
Value (Ω)
800-1200
1800-3000
1800-3000
800-1200
1600-2500
Continuity
Yes
Yes
Yes
Yes
Yes
If the resistance values in steps 3, 4, and 5 are
within specifications, go to step 6.
If the resistance values are not within
specifications, or a momentary short or open
circuit was detected during rotation (step 4), the
TPS needs to be replaced, go to step 7.
6. Check the TPS circuits (input, ground) between
the TPS plug and the main harness connector for
continuity, damage, etc. See chart on page 5B-26
or 5B-29.
5B.7
5B
Section 5B
EFI Fuel System
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Pin
circuits #8 and #4.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Pin
circuits #8 and #4.
7. Locate the service connector plug in the wiring
harness. Connect a jumper wire from the TPS
initialization pin #24 (violet wire) to the battery
voltage pin (red wire), or use the jumper
connector plug with the blue jumper wire. See
Figure 5B-7.
a. Repair or replace as required.
b. Turn the idle speed screw back in to its
original setting.
c. Reconnect connector plugs, start engine and
retest system operation.
7. Remove the two mounting screws from the TPS.
Save the screws for reuse. Remove and discard
the faulty TPS. Install the replacement TPS and
secure with the original mounting screws.
a. Reconnect both connector plugs.
b. Perform the appropriate “TPS Initialization
Procedure” integrating the new sensor to the
ECU.
TPS Initialization Procedure
For “24 Pin” (MSE 1.0) Plastic-Cased ECU only
1. Check that the basic engine, all sensors, fuel, fuel
pressure, and battery are good and functionally
within specifications.
Important!
2. Remove/disconnect all external loads from the
engine (belts, pumps, electric PTO clutch,
alternator, rectifier-regulator, etc.).
3. Start the engine and allow it to warm up for 5-10
minutes, so oil temperature is above 55°C (130°F).
4. Move the throttle control to the idle position and
allow the engine to stabilize for a minimum of
one minute.
5. Install a heavy rubber band around the throttle
lever and the manifold boss. On some EFI engines
there is a dampening spring on the end of the idle
speed screw. The dampening spring (if used)
should be fully compressed and the tab on the
throttle lever in direct contact with the speed
screw. Adjust the idle speed to 1500 RPM, using a
tachometer.
6. Shut off the engine.
5B.8
Figure 5B-7. Service Connector Plug, Plastic
Cased ECU Harness.
8. Hold the throttle against the idle speed stop
screw, turn the ignition switch to the “on”
position (do not start the engine), and observe the
Malfunction Indicator Light (MIL).
a. The light should blink on/off quickly for
approximately 3 seconds and then go off and
stay off, indicating the initialization
procedure has been successful.
b. If the light stays on or blinking ceases
prematurely, the procedure was unsuccessful
and must be repeated. Possible causes for
unsuccessful learning may be: 1) Movement
occurred in either the TPS or throttle shaft
during procedure, 2) Crankshaft movement
wasdetected by the speed sensor during
procedure, 3) Throttle plate position was out
of learnable range (recheck the 1500 RPM idle
speed adjustment), or 4) Problem with ECU
or TPS.
9. When the initialization procedure has been
successfully completed, turn off the key switch,
remove the jumper wire or connector, and
remove the rubber band from the throttle lever.
10. Disconnect the ECU connector plug or the
negative (-) battery cable temporarily (one
minute minimum) to clear all learned
adjustments.
Section 5B
EFI Fuel System
11. Reconnect the battery cable and all external loads.
Remove the rubber band from the throttle lever.
Readjust the idle speed to the equipment
manufacturer’s specified setting and recheck the
high-speed, no-load RPM setting. Observe the
overall performance.
TPS Initialization Procedure
For “32 Pin” (MSE 1.1) Plastic-Cased ECU Only
(“Auto-Learn” Initialization)
1. Check that the basic engine, all sensors, fuel, fuel
pressure, and battery are good and functionally
within specifications.
Important!
2. Remove/disconnect all external loads from the
engine (belts, pumps, electric PTO clutch,
alternator, rectifier-regulator, etc.).
3. Locate the service connector plug in the wiring
harness. To initiate the TPS auto-learn function,
connect a jumper wire from the TPS initialization
pin #24 (violet wire) to the battery voltage pin
(red wire), or use the jumper plug with the blue
jumper wire. If using the PC-based diagnostic
software (see Section 2), go to “Special Tests” and
follow the prompts to complete.
4. Start the engine and immediately observe the
Malfunction Indicator Light (MIL). The light
should start blinking 4 consecutive times every 2
seconds.
9. Shut off the engine. If the learn procedure was
successfully completed, the external loads
removed/disconnected in Step 2 may be
reconnected.
If the procedure was unsuccessful see Steps a.
and b. following.
a. If the “MIL” goes back to blinking 4
consecutive blinks every 2 seconds during the
procedure, the engine and O2 sensor have
cooled down and gone out of “closed-loop”
operation, prohibiting the learning from
occurring. Repeat Steps 6-9.
b. If the “MIL” stays “on” continuously for more
than 15 seconds during the procedure, there is
probably a fault code present, turn off the
ignition. Then initiate the fault code sequence,
by turning the key switch on-off-on-off-on,
leaving the key “on” in the last sequence (each
key on/off sequence must be less than 2.5
seconds long). The fault detected must be
corrected before the “auto-learn” function can
be re-initiated. The PC-based diagnostic
software may be used to read out the fault
code and assist with troubleshooting and
repair.
Engine (Oil) Temperature Sensor
5. Remove the jumper wire or plug from the service
connector plug.
6. Run the engine at full throttle (above 3000 RPM),
to warm up the engine and initiate O2 sensor
function in “closed-loop” operation.
7. Watch the “MIL”. When the light starts blinking
rapidly, (5 blinks per second), move the throttle
lever to the low idle speed position. Check and
adjust the idle speed to 1500 RPM, using a
tachometer. The lamp should continue to blink
rapidly for another 30 seconds before switching
to a slow blink.
Figure 5B-8. Engine (Oil) Temperature Sensor.
8. When the “MIL” blinks slowly, do not do
anything but wait until the “MIL” shuts off. This
indicates that this procedure has been completed
successfully.
5B.9
5B
Section 5B
EFI Fuel System
General
The engine (oil) temperature sensor (Figure 5B-8) is
used by the system to help determine fuel
requirements for starting (a cold engine needs more
fuel than one at or near operating temperature).
Mounted in the oil filter adapter housing, it has a
temperature-sensitive resistor that extends into the oil
flow. The resistance changes with oil temperature,
altering the voltage sent to the ECU. Using a table
stored in its memory, the ECU correlates the voltage
drop to a specific temperature. Using the fuel delivery
“maps”, the ECU then knows how much fuel is
required for starting at that temperature.
Service
The temperature sensor is a sealed, non-serviceable
assembly. A faulty sensor must be replaced. If a blink
code indicates a problem with the temperature sensor,
it can be tested as follows:
1. Remove the temperature sensor from the adapter
housing and cap or block the adapter hole.
2. Wipe the sensor clean and allow it to reach room
temperature (20°C, 68°F).
3. Unplug the main harness connector from the
ECU.
4. With the sensor still connected, check the
temperature sensor circuit resistance between the
#6 and #4 pin terminals (see chart on page 5B.26
(24 pin) or 5B.29 (32 pin) for pin positions). The
value should be 2375-2625 Ω.
5. Unplug the sensor from the wire harness and
check the sensor resistance separately. Resistance
value should again be 2375-2625 Ω.
Oxygen Sensor
Figure 5B-9. Oxygen Sensor.
General
The oxygen sensor functions like a small battery,
generating a voltage signal to the ECU based upon the
difference in oxygen content between the exhaust gas
and the ambient air.
The tip of the sensor, protruding into the exhaust gas,
is hollow (see cutaway Figure 5B-10). The outer
portion of the tip is surrounded by the exhaust gas,
with the inner portion exposed to the ambient air.
When the oxygen concentration on one side of the tip
is different than that of the other side, a voltage signal
between 0.2 and 1.0 volts is generated between the
electrodes and sent to the ECU. The voltage signal
tells the ECU if the engine is straying from the ideal
14.7:1 fuel mixture, and the ECU then adjusts the
injector pulse accordingly.
1
2
3
4
5
6
7 8
a. If the resistance is out of specifications,
replace the temperature sensor.
b. If it is within specifications, proceed to Step 6.
6. Check the circuits (input, ground), from the main
harness connector to the sensor plug for
continuity, damage, etc. Connect one ohmmeter
lead to pin terminal #6 in the main harness
connector (as in step 4). Connect the other lead to
terminal #1 in the sensor plug (see diagram).
Continuity should be indicated. Repeat the test
between pin terminal #4 and terminal #2 in the
sensor plug.
5B.10
1. Connection Cable
2. Disc Spring
3. Ceramic Support Tube
4. Protective Sleeve
5. Contact Element
6. Sensor Housing
7. Active Ceramic Sensor
8. Protective Tube
Figure 5B-10. Cutaway of Oxygen Sensor.
Section 5B
EFI Fuel System
The oxygen sensor can function only after being
heated by exhaust temperatures to a minimum of
375°C (709°F). A cold oxygen sensor will require
approximately 1-2 minutes at moderate engine load to
warm sufficiently to generate a voltage signal. Proper
grounding is also critical. The oxygen sensor grounds
through the metal shell, so a good, solid, unbroken
ground path back through the exhaust system
components, engine, and wiring harness is required.
Any disruption or break in the ground circuit can
affect the output signal and trigger misleading fault
codes. Keep that in mind when doing any
troubleshooting associated with the oxygen sensor.
The oxygen sensor can also be contaminated by leaded
fuel, certain RTV and/or other silicone compounds,
carburetor cleaners, etc. Use only those products
indicated as “O2 Sensor Safe.”
Service
Like the other sensors already discussed, the oxygen
sensor is a non-serviceable component. Complete
replacement is required if it is faulty. The sensor and
wiring harness can be checked as follows.
NOTE: All tests should be conducted with a good
quality, high-impedance, digital VOA meter
for accurate results.
1. Oxygen sensor must be hot (minimum of 400°C,
752°F). Run engine for about 5 minutes. With the
engine running, disconnect the oxygen sensor
lead from the wiring harness. Set VOA meter for
DC volts and connect the red lead to the
disconnected sensor lead, and the black lead to
the sensor shell. Look for a voltage reading from
0.2 v-1.0 v.
a. If voltage is in the specified range, go to Step
2.
b. If voltage is not in the specified range,
reconnect the oxygen sensor lead. With the
lead connected, probe or connect the sensor
connection with the red VOA meter lead.
Attach the black VOA meter lead to a good
ground location. Start and run the engine at
3/4 throttle and note the voltage reading being
signaled by the oxygen sensor. The reading
should cycle between 0.2 v and 1.0 v, which
indicates the oxygen sensor is functioning
normally and fuel delivery is within
prescribed parameters. If the voltage readings
show a steady decline, rev the engine and
check the indicated reading again. If the
voltage momentarily increases and then again
declines, without cycling, the engine may be
running lean due to incorrect TPS initialization.
Shut off the engine, perform TPS initialization,
and then repeat the test. If TPS initialization
cannot be achieved, perform step c.
c. Replace the oxygen sensor (see next page).
Run the engine long enough to bring the new
sensor up to temperature and repeat the
output test from step 1. The cycling voltage
from 0.2 to 1.0 v should be indicated.
2. Move the black voltmeter lead to the engine
ground location and repeat the output test. The
same voltage (0.2 v-1.0 v) should be indicated.
a. If the same voltage reading exists, go on to
Step 3.
b. If the voltage output is no longer correct, a
bad ground path exists between the sensor
and the engine ground. Touch the black lead at
various points, backtracking from the engine
ground back toward the sensor, watching for a
voltage change at each location. If the correct
voltage reading reappears at some point,
check for a problem (rust, corrosion, loose
joint or connection) between that point and
the previous checkpoint. For example, if the
reading is too low at points on the crankcase,
but correct voltage is indicated when the black
lead is touched to the skin of the muffler, the
flange joints at the exhaust ports become
suspect.
3. With the sensor still hot (minimum of 400°C,
752°F), switch the meter to the Rx1K or Rx2K
scale and check the resistance between the sensor
lead and the sensor case. It should be less than
Ω.
2.0 KΩ
Ω go to
a. If the resistance is less than 2.0 KΩ
Step 4.
Ω, the
b. If the resistance is greater than 2.0 KΩ
oxygen sensor is bad, replace it.
4. Allow the sensor to cool (less than 60°C, 140°F)
and retest the resistance with the meter set on the
Rx1M scale. With sensor cool, the resistance
Ω.
should be greater than 1.0 MΩ
Ω go to
a. If the resistance is greater than 1.0 MΩ
Step 5.
5B.11
5B
Section 5B
EFI Fuel System
Ω, the
b. If the resistance is less than 1.0 MΩ
sensor is bad, replace it.
5. With the oxygen sensor disconnected and
engine not running, disconnect the main
harness connector from the ECU and set the
meter to the Rx1 scale. Check the circuit
continuity as follows:
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Check
for continuity from pin #15 of the ECU
connector (see page 5B.26) to the shell of the
oxygen sensor, and from pin #11 to the sensor
connector terminal of the main harness. Both
tests should indicate continuity.
2. Loosen and remove the oxygen sensor from the
exhaust manifold/muffler assembly.
3. Apply anti-seize compound sparingly to
threads of new oxygen sensor, if none already
exists. DO NOT get any on the tip as it will
contaminate the sensor. Install sensor and
torque to 50-60 N·m (37-44 ft. lb.).
4. Reconnect the lead to the wiring harness
connector. Make sure it can not contact hot
surfaces, moving parts, etc.
5. Test run the engine.
Electrical Relay
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Check
for continuity from pin #19 of the ECU
connector (see page 5B.29) to the shell of the
oxygen sensor, and from pin #20 to the sensor
terminal of the main harness. Both tests should
indicate continuity.
a. If there is no continuity displayed in either
of the tests, check the harness circuit for
breaks or damage, and the connections for
poor contact, moisture, or corrosion. If no
continuity was found in the first test, also
check for a poor/broken ground path back
through the exhaust system, engine, and
mounting (sensor is grounded through its
shell).
b. If continuity is indicated, go to step 6.
6. With the key switch in the ‘‘on/run’’ position,
using a high impedance voltmeter, check the
voltage from the wiring harness oxygen sensor
connector to the engine ground location. Look
for a steady voltage from 350-550 mv
(0.35 - 0.55 v).
a. If the voltage reading is not as specified,
move the black voltmeter lead to the
negative post of the battery, to be certain of
a good ground. If the voltage is still not
correct, the ECU is probably bad.
b. If the voltage readings are correct, clear the
fault codes and run the engine to check if
any fault codes reappear.
To Replace Oxygen Sensor
1. Disconnect the oxygen sensor connector from
the wiring harness.
5B.12
Figure 5B-11. Electrical Relay.
General
The electrical relay is used to supply power to the
injectors, coil, and fuel pump. When the key switch is
turned “on” and all safety switch requirements met,
the relay provides 12 volts to the fuel pump circuit,
injectors, and ignition coils. The fuel pump circuit is
continuously grounded, so the pump is immediately
activated and pressurizes the system. Activation of the
ignition coils and fuel injectors is controlled by the
ECU, which grounds their respective ground circuits
at the proper times.
Service
A malfunctioning relay can result in starting or
operating difficulties. The relay and related wiring can
be tested as follows:
1. Disconnect the relay connector plug from the
relay.
Section 5B
EFI Fuel System
2. Connect the black lead of VOA meter to a chassis
ground location. Connect the red lead to the #86
terminal in relay connector (see Figure 5B-12). Set
meter to test resistance (Rx1). Turn ignition
switch from “off” to “on.” Meter should indicate
continuity (ground circuit is completed) for 1 to 3
seconds. Turn key switch back off.
a. Clean the connection and check wiring if
circuit was not completed.
Terminal #85 Ignition Switch
Voltage
Terminal #87A Not used
Terminal #87 Feed To Ignition
Coils, Fuel
Injectors, and
Fuel Pump
Terminal #86 ECU Controlled
Ground
Terminal #30 Permanent Battery Voltage
Figure 5B-12. Relay Connector.
3. Set meter for DC voltage. Touch red tester lead
to the #30 terminal in relay connector. A
reading of 12 volts should be indicated at all
times.
4. Connect the red lead of meter to the #85
terminal in relay connector. Turn key switch to
the “on” position. Battery voltage should be
present.
Terminal #87 Feed To
Ignition Coils,
Fuel Injectors,
and Fuel Pump
Terminal #86 - ECU
Controlled Ground
Terminal #85 Ignition Switch
Voltage
Terminal
#87A Not used
Terminal #30 Permanent Battery Voltage
Figure 5B-13. Relay Terminal Details.
5. Connect an ohmmeter (Rx1 scale) between the
#85 and #86 terminals in the relay. There should
be continuity. See Figure 5B-13.
6. Attach ohmmeter leads to the #30 and #87
terminals in relay. First, there should be no
continuity. Using a 12 volt power supply, connect
the positive (+) lead to the #85 terminal and touch
the negative (-) lead to the #86 terminal. When 12
volts is applied, the relay should activate and
continuity should exist between the #30 and #87
terminals. Repeat the test several times. If, at any
time the relay fails to activate the circuit, replace
the relay.
Fuel Injectors
a. No voltage present indicates a problem
with the key switch, in the wiring, or at the
connector.
b. If voltage is present, the wiring to the
connector is good. Turn the ignition switch
‘‘off’’ and proceed to Step 5 to test the relay.
Figure 5B-14. Style 1 Fuel Injector.
5B.13
5B
Section 5B
EFI Fuel System
1
2
3
5
4
6
7
Figure 5B-15. Style 2 Fuel Injector.
General
The fuel injectors mount into the throttle body/intake
manifold, and the fuel rail attaches to them at the top
end. Replaceable O-Rings on both ends of the injector
prevent external fuel leakage and also insulate it from
heat and vibration. A special clip connects each
injector to the fuel rail and holds it in place. The
O-Rings should be replaced anytime the injector is
removed.
When the key switch is on and the relay is closed, the
fuel rail is pressurized, and voltage is present at the
injector. At the proper instant, the ECU completes the
ground circuit, energizing the injector. The valve
needle in the injector is opened electromagnetically,
and the pressure in the fuel rail forces fuel down
through the inside. The “director plate” at the tip of
the injector (see inset) contains a series of calibrated
openings which directs the fuel into the manifold in a
cone-shaped spray pattern.
Multi-Orifice
Director Plate With
Calibrated Opening
1. Filter Strainer In
4. Valve Housing
Fuel Supply
5. Armature
2. Electrical Connection
6. Valve Body
3. Solenoid Winding
7. Valve Needle
Figure 5B-16. Fuel Injector Details.
The injector is opened and closed once for each
crankshaft revolution, however only one-half the total
amount of fuel needed for one firing is injected during
each opening. The amount of fuel injected is
controlled by the ECU and determined by the length
of time the valve needle is held open, also referred to
as the “injection duration” or “pulse width”. It may
vary in length from 1.5-8 milliseconds depending on
the speed and load requirements of the engine.
Service
Injector problems typically fall into three general
categories: electrical, dirty/clogged, or leakage. An
electrical problem usually causes one or both of the
injectors to stop functioning. Several methods may be
used to check if the injectors are operating.
1. With the engine running at idle, feel for
operational vibration, indicating that they are
opening and closing.
2. When temperatures prohibit touching, listen for a
buzzing or clicking sound with a screwdriver or
mechanic’s stethoscope (see Figure 5B-17).
5B.14
Section 5B
EFI Fuel System
Listen Here
Figure 5B-17. Checking Injectors.
3. Disconnect the electrical connector from an
injector and listen for a change in idle
performance (only running on one cylinder) or a
change in injector noise or vibration.
If an injector is not operating, it can indicate either a
bad injector, or a wiring/electrical connection
problem. Check as follows:
NOTE: Do not apply voltage to the fuel injector(s).
Excessive voltage will burn out the
injector(s). Do not ground the injector(s) with
the ignition “on.” Injector(s) will open/turn
on if relay is energized.
a. If flashing occurs, use an ohmmeter (Rx1
scale) and check the resistance of each
injector across the two terminals. Proper
resistance is 12-20 Ω. If injector resistance is
correct, check whether the connector and
injector terminals are making a good
connection. If the resistance is not correct,
replace the injector following steps 1-8 and
13-16 below.
b. If no flashing occurs, reattach the connectors
to both injectors. Disconnect the main harness
connector from the ECU and the connector
from the relay. Set the ohmmeter to the Rx1
scale and check the injector circuit resistance
as follows:
“24 Pin” (MSE 1.0) Plastic-Cased ECU:
Check the resistance between relay terminal
#87 and pin #16 in the main connector. Then
check the resistance between relay terminal
#87 and pin #17. Resistance should be 4-15 Ω
for each circuit.
“32 Pin” (MSE 1.1) Plastic-Cased ECU:
Check the resistance between relay terminal
#87 and pin #14 in the main connector. Then
check the resistance between relay terminal
#87 and pin #15. Resistance should be
4-15 Ω for each circuit.
Check all electrical connections, connectors, and
wiring harness leads if resistance is incorrect.
Injector leakage is very unlikely, but in those rare
instances it can be internal (past the tip of the valve
needle), or external (weeping around the injector
body). See Figure 5B-19. The loss of system pressure
from the leakage can cause hot restart problems and
longer cranking times. To check for leakage it will be
necessary to loosen or remove the blower housing
which may involve removing the engine from the unit.
Figure 5B-18. Volt Noid Light.
1. Disconnect the electrical connector from both
injectors. Plug a 12 volt noid light (part of EFI
Service Kit, see Section 2) into one connector.
2. Make sure all safety switch requirements are met.
Crank the engine and check for flashing of the
test light. Repeat test at other connector.
5B.15
5B
Section 5B
EFI Fuel System
10. Remove the manifold mounting bolts and separate
the throttle body/manifold from the engine
leaving the TPS, fuel rail, air baffle, injectors and
line connections intact. Discard the old gaskets.
Check For Leaks
Figure 5B-19. Injector Inspection Points.
1. Engine must be cool. Depressurize fuel system
through test valve in fuel rail.
2. Disconnect spark plug leads from spark plugs.
3. Remove the air cleaner outer cover, inner wing
nut, element cover and air cleaner element/
precleaner. Service air cleaner components as
required.
4. Remove the two screws securing the air cleaner
base to the throttle body manifold. Remove the
air cleaner base to permit access to the injectors.
Check condition of air cleaner base gasket,
replace if necessary.
5. Remove the flywheel screen if it overlaps the
blower housing.
6. If the engine has a radiator-type oil cooler
mounted to the blower housing, remove the two
oil cooler mounting screws.
7. Remove the blower housing mounting screws.
Note the location of the plated (silver) screw
attaching the rectifier/regulator ground lead.
Remove the blower housing.
8. Thoroughly clean the area around and including
the throttle body/manifold and the injectors.
9. Disconnect the throttle linkage and damper
spring from the throttle lever. Disconnect the TPS
lead from the harness.
5B.16
11. Position the manifold assembly over an
appropriate container and turn the key switch
“on” to activate the fuel pump and pressurize the
system. Do not turn switch to “start” position.
12. If either injector exhibits leakage of more than two
to four drops per minute from the tip, or shows
any sign of leakage around the outer shell, turn
the ignition switch off and replace the injector as
follows.
13. Depressurize the fuel system following the
procedure in the fuel warning on page 5B.2.
Remove the two fuel rail mounting screws.
14. Clean any dirt accumulation from the sealing/
mounting area of the faulty injector(s) and
disconnect the electrical connector(s).
15. Pull the retaining clip off the top of the injector(s).
Disconnect the fuel rail and remove the injector(s)
from the manifold.
16. Reverse the appropriate procedures to install the
new injector(s) and reassemble the engine. Use
new O-Rings any time an injector is removed (new
replacement injectors include new O-Rings).
Lubricate O-Rings lightly with oil. Torque the fuel
rail and blower housing mounting screws to
3.9 N·m (35 in. lb.), and the intake manifold and
air cleaner mounting screws to 9.9 N·m
(88 in. lb.).
Injector problems due to dirt or clogging are generally
unlikely due to the design of the injectors, the high fuel
pressure, and the detergent additives in the gasoline.
Symptoms that could be caused by dirty/clogged
injectors include rough idle, hesitation/stumble during
acceleration, or triggering of fault codes related to fuel
delivery. Injector clogging is usually caused by a
buildup of deposits on the director plate, restricting
the flow of fuel, resulting in a poor spray pattern.
Some contributing factors to injector clogging include
higher than normal operating temperatures, short
operating intervals, and dirty, incorrect, or poor quality
fuel. Cleaning of clogged injectors is not
recommended; they should be replaced. Additives and
higher grades of fuel can be used as a preventative
measure if clogging has been a problem.
Section 5B
EFI Fuel System
Ignition System
General
A high-voltage, solid-state, battery ignition system is
used with the EFI system. The ECU controls the
ignition output and timing through transistorized
control of the primary current delivered to the coils.
Based on input from the speed sensor, the ECU
determines the correct firing point for the speed at
which the engine is running. At the proper instant, it
releases the flow of primary current to the coil. The
primary current induces high voltage in the coil
secondary, which is then delivered to the spark plug.
Each coil fires every revolution, but every other spark
is "wasted".
Service
Except for removing the spark plug lead by
unscrewing it from the secondary tower (see Figure
5B-20), no coil servicing is possible. If a coil is
determined to be faulty, replacement is necessary. An
ohmmeter may be used to test the wiring and coil
windings.
2. Disconnect connector from relay and locate
terminal #87 in connector.
3. Using an ohmmeter set on the Rx1 scale, check
the resistance in circuits as follows:
"24 Pin" (MSE 1.0) Plastic-Cased ECU: Check
between terminal #87 and pin #22 for coil #1.
Repeat the test between terminal #87 and pin #23
for coil #2.
"32 Pin" (MSE 1.1) Plastic-Cased ECU: Check
between terminal #87 and pin #30 for coil #1.
Repeat the test between terminal #87 and pin #31
for coil #2.
A reading of 1.8-4.0 Ω in each test indicates that
the wiring and coil primary circuits are OK.
a. If reading(s) are not within specified range,
check and clean connections and retest.
b. If reading(s) are still not within the specified
range, test the coils separately from main
harness as follows:
1) Disconnect the red and black primary
leads from the coil terminals.
2) Connect an ohmmeter set on the Rx1
scale to the primary terminals. Primary
resistance should be 1.8-2.5 Ω.
Figure 5B-20. Ignition Coil.
NOTE: Do not ground the coils with the ignition
‘‘on,’’ as they may overheat or spark.
Testing
1. Disconnect the main harness connector from the
ECU.
"24 Pin" (MSE 1.0) Plastic-Cased ECU: Locate
pins #22 and #23 in the 24 pin connector. See page
5B.26.
"32 Pin" (MSE 1.1) Plastic Cased ECU: Locate
pins #30 and #31 in the 32 pin connector. See page
5B.29.
3) Disconnect the secondary lead from the
spark plug. Connect an ohmmeter set on
the Rx10K scale between the spark plug
boot terminal and the red primary
terminal. Secondary resistance should
be 13,000-17,500 Ω.
4) If the secondary resistance is not within
the specified range, unscrew the spark
plug lead nut from the coil secondary
tower and remove the plug lead. Repeat
step b. 3, testing from the secondary tower
terminal to the red primary terminal. If
resistance is now correct, the coil is good,
but the spark plug lead is faulty, replace
the lead. If step b. 2 resistance was
incorrect and/or the secondary resistance
is still incorrect, the coil is faulty and
needs to be replaced.
5B.17
5B
Section 5B
EFI Fuel System
EFI engines are equipped with Champion RC12YC
(Kohler Part No. 12 132 02-S) resistor spark plugs.
Equivalent alternate brand plugs can also be used, but
must be resistor plugs or permanent damage to the
ECU will occur, in addition to affecting operation.
Proper spark plug gap is 0.76 mm (0.030 in.).
The condition of the wiring, connectors, and terminal
connections is essential to system function and
performance. Corrosion, moisture, and poor
connections are more likely the cause of operating
problems and system errors than an actual
component. Refer to the ‘‘Troubleshooting –
Electrical’’ section for additional information.
Wiring Harness
Battery Charging System
The wiring harness used in the EFI system connects
the electrical components, providing current and
ground paths for the system to operate. All input and
output signaling occurs through a special all weather
connector that attaches and locks to the ECU (see
Figures 5B-21 and 5B-22).
EFI engines are equipped with either a 15 or 25 amp
charging system to accommodate the combined
electrical demands of the ignition system and the
specific application. Charging system troubleshooting
information is provided in Section 8.
Spark Plugs
®
Fuel Components
Fuel Pump
Internal
External
Figure 5B-21. “24 Pin” (MSE 1.0) Plastic-Cased
ECU Connector.
Figure 5B-23. Fuel Pump Styles.
General
An electric fuel pump is used to transfer fuel in the
EFI system. Depending on the application, the pump
may be inside the fuel tank, or in the fuel line near the
tank. The pumps are rated for a minimum output of
25 liters per hour at 39 psi. The pumps have an
internal 60-micron filter. In addition, the in-tank style
pumps will have a pre-filter attached to the inlet. Inline pump systems may also have a filter between the
tank and the pump on the pickup/low pressure side.
The final fuel filter is covered separately on page
5B-21.
Figure 5B-22. “32 Pin” (MSE 1.1) Plastic-Cased
ECU Connector.
5B.18
When the key switch is turned “on” and all safety
switch requirements are met, the ECU, through the
relay activates the fuel pump, which pressurizes the
system for start-up. If the key switch is not promptly
turned to the “start” position, the engine fails to start,
or the engine is stopped with the key switch “on” (as
in the case of an accident), the ECU switches off the
Section 5B
EFI Fuel System
pump preventing the continued delivery of fuel. In
this situation, the MIL will go on, but it will go back
off after 4 cranking revolutions if system function is
OK. Once the engine is running, the fuel pump
remains on.
Service
The fuel pumps are non-serviceable and must be
replaced if determined to be faulty. If a fuel delivery
problem is suspected, make certain the pump is being
activated through the relay, all electrical connections
are properly secured, the fuses are good, and a
minimum of 7.0 volts is being supplied. If during
cranking, voltage drops below 7.0 volts, a reduction of
fuel pressure may occur resulting in a lean starting
condition. If required, testing of the fuel pump and
relay may be conducted.
b. If the voltage was below 7, test the wiring
harness and relay as covered in the
‘‘Electrical Relay’’ section.
4. If voltage at the plug was good, and there was
continuity across the pump terminals, reconnect
the plug to the pump, making sure you have a
good connection. Turn on the key switch and
listen for the pump to activate.
a. If the pump starts, repeat steps 1 and 2 to
verify correct pressure.
b. If the pump still does not operate, replace it.
Fuel Pressure Regulator
1. Connect the black hose of Pressure Tester (part of
EFI Service Kit, see Section 2) to the test valve in
the fuel rail. Route the clear hose into a portable
gasoline container or the equipment fuel tank.
5B
2. Turn on the key switch to activate the pump and
check the system pressure on the gauge. If system
pressure of 39 psi ± 3 is observed, the relay, fuel
pump, and regulator are working properly. Turn
key switch off and depress the valve button on
the tester to relieve the system pressure.
a. If the pressure is too high, and the regulator
is outside the tank (just down line from the
pump), check that the return line from the
regulator to the tank is not kinked or
blocked. If the return line is good, replace
the regulator (see ‘‘Regulator Service’’ on
page 5B.20).
Figure 5B-24. External Fuel Pressure Regulators.
b. If the pressure is too low, install in-line ‘‘T’’
between the pump and the regulator and
retest the pressure at that point. If it is too low
there also, replace the fuel pump.
3. If the pump did not activate (step 2), disconnect
the plug from the fuel pump. Connect a DC
voltmeter across the terminals in the plug, turn
on the key switch and observe if a minimum of 7
volts is present. If voltage is between 7 and 14,
turn key switch off and connect an ohmmeter
between the terminals on the pump to check for
continuity.
Figure 5B-25. Internal Fuel Pressure Regulators.
a. If there was no continuity between the pump
terminals, replace the fuel pump.
5B.19
Section 5B
EFI Fuel System
General
The fuel pressure regulator assembly maintains the
required operating system pressure of 39 psi ± 3. A
rubber-fiber diaphragm (see Figure 5B-26) divides the
regulator into two separate sections; the fuel chamber
and the pressure regulating chamber. The pressure
regulating spring presses against the valve holder
(part of the diaphragm), pressing the valve against the
valve seat. The combination of atmospheric pressure
and regulating spring tension equals the desired
operating pressure. Any time the fuel pressure against
the bottom of the diaphragm exceeds the desired (top)
pressure, the valve opens, relieving the excess
pressure, returning the excess fuel back to the tank.
Pressure
Regulating
Spring
a. Remove the two screws securing the
mounting bracket to the regulator housing.
Remove the O-Ring and pull the regulator out
of the housing.
b. Remove the snap ring and remove regulator
from base/holder.
Internal (In-Tank) Regulator Remove the three screws securing the retaining
ring and regulator in the base/holder assembly.
Grasp and pull the regulator out of the base/
holder. See Figure 5B-28.
Pressure
Regulating
Chamber
Diaphragm
Valve
Valve Seat
Fuel Chamber
Inlet Port
Return Port (To Tank)
Outlet Port
(To Fuel Rail)
Figure 5B-26. Fuel Pressure Regulator Details.
Service
Depending on the application, the regulator may be
located in the fuel tank along with the fuel pump, or
outside the tank just down line from the pump. The
regulator is a sealed, non-serviceable assembly. If it is
faulty, it must be separated from the base/holder
assembly and replaced as follows:
Figure 5B-27. External Regulators and Base/
Holders.
1. Shut engine off, make sure engine is cool, and
disconnect the negative (-) battery cable.
2. Depressurize fuel system through test valve in
fuel rail (see fuel warning on page 5B.2).
3. Access the regulator assembly as required and
clean any dirt or foreign material away from the
area.
4. External Regulator Based upon the style of regulator used: See
Figure 5B-27:
5B.20
Figure 5B-28. Internal (In-Tank) Regulator and
Base/Holder.
5. Always use new O-Rings and hose clamps when
installing a regulator. A new replacement
regulator will have new O-Rings already
installed. Lubricate the O-Rings (external
regulator) with light grease or oil.
Section 5B
EFI Fuel System
6. Install the new regulator by carefully pushing
and rotating it slightly into the base or housing.
Fuel Rail
a. External Regulators with Square Base
Housing Only; Install a new O-Ring between
the regulator and the mounting bracket. Set
the mounting bracket into position.
Fuel Rail
b. Secure the regulator in the base with the
original retaining ring or screws. Be careful
not to dent or damage the body of the
regulator as operating performance can be
affected.
7. Reassemble and connect any parts removed in
step 3.
8. Reconnect the negative (-) battery cable.
9. Recheck regulated system pressure at fuel rail test
valve.
Fuel Filter
EFI engines use a high-volume, high-pressure, 10-15
micron, in-line fuel filter.
TPS
Locking Cups
Fuel Injector
Figure 5B-30. Throttle Body/Intake Manifold.
General
The fuel rail is a formed tube assembly that feeds fuel
to the top of the injectors. The tops of the injectors fit
into formed cups in the fuel rail. When the rail is
fastened to the manifold, the injectors are locked into
place. A small retaining clip provides a secondary
lock. Incorporated into the fuel rail is a pressure relief/
test valve for testing operating pressure or relieving
fuel system pressure for servicing. The fuel supply
line is attached to the barbed end of the fuel rail with
an Oetiker hose clamp.
Service
The fuel rail is mounted to the throttle body/intake
manifold. No specific servicing is required unless
operating conditions indicate that it needs internal
cleaning or replacement. It can be detached by
removing the two mounting screws and the injector
retaining clips. Thoroughly clean the area around all
joints and relieve any pressure before starting any
disassembly.
Figure 5B-29. In-Line Fuel Filter.
Fuel Line
Service
Filter replacement is recommended every 1500 hours
of operation or more frequently under extremely
dusty or dirty conditions. Use only the specified filter,
and install it according to the directional arrows. Do
not use a substitute filter as operating performance
and safety can be affected. Relieve system pressure
through the safety valve in the fuel rail before
servicing.
Figure 5B-31. High Pressure Fuel Line.
5B.21
5B
Section 5B
EFI Fuel System
General
Special low permeation high-pressure fuel line with
an SAE 30 R9 rating is required for safe and reliable
operation, due to the higher operating pressure of the
EFI system. If hose replacement is necessary, order
Fuel Line Service Kit Part No. 25 111 37-S (containing
60” of high-pressure hose and 10 Oetiker clamps), or
use only the type of hose specified. Special Oetiker
clamps (Kohler Part No. 24 237 05-S) are used on all
fuel line connections to prevent tampering and safety
hazards with the high fuel pressure. The old clamp
must be cut to open a connection, so replacement is
necessary each time. Oetiker Clamp Pliers (part of EFI
Service Kit, see Section 2) is used to crimp the
replacement clamps.
CAUTION:
Fuel lines between the fuel pump and fuel rail must be made
from SAE 30 R9 fuel line. Standard fuel line (SAE 30 R7)
may only be used between the fuel tank and pump (5/16”
ID) and for the return line from the pressure regulator to
the tank (1/4” ID). All high-pressure fuel line connections
must be secured with Oetiker clamps (Kohler Part No.
24 237 05-S), installed/crimped with the corresponding
pliers.
Throttle Body/Intake Manifold Assembly
Service
The throttle body/intake manifold is serviced as an
assembly, with the throttle shaft, TPS, throttle plates,
and idle speed adjusting screw installed. The throttle
shaft rotates on needle bearings (non-serviceable),
capped with rubber seals to prevent air leaks. A
throttle shaft repair kit is available to replace the shaft
if worn or damaged. The appropriate “TPS
Initialization Procedure” must be performed after any
throttle shaft service.
Idle Speed Adjustment (RPM)
General
The idle speed is the only adjustment that may be
performed on the EFI system. The standard idle speed
setting for EFI engines is 1500 RPM, but certain
applications might require a different setting. Check
the equipment manufacturer’s recommendation.
For starting and warm up, the ECU will adjust the fuel
and ignition timing, based upon ambient temperature,
engine temperature, and loads present. In cold
conditions, the idle speed will probably be higher than
normal for a few moments. Under other conditions,
the idle speed may actually start lower than normal,
but gradually increase to the established setting as
operation continues. Do not attempt to circumvent
this warm up period, or readjust the idle speed during
this time. The engine must be completely warmed up,
in closed loop operating mode for accurate idle
adjustment.
Adjustment Procedure
1. Make sure there are no fault codes present in the
ECU memory.
2. Start the engine and allow it to fully warm up
and establish closed looped operation
(approximately 5-10 min.).
Figure 5B-32. Upper Throttle Body/Intake Manifold
Details.
General
The EFI engines have no carburetor, so the throttle
function (regulate incoming combustion airflow) is
incorporated in the intake manifold assembly. The
manifold consists of a one-piece aluminum casting
which also provides mounting for the fuel injectors,
throttle position sensor, fuel rail, air baffle, idle speed
screw, and air cleaner assembly.
5B.22
3. Place the throttle control in the ‘‘idle/slow’’
position and check the idle speed with a
tachometer. Turn the idle speed screw in or out as
required to obtain 1500 RPM, or the idle speed
specified by the equipment manufacturer. See
Figure 5B-33.
4. The idle speed adjustment can affect the high idle
speed setting. Move the throttle control to the full
throttle position and check the high idle speed.
Adjust as necessary to 3750 RPM, or the speed
specified by the equipment manufacturer.
Section 5B
EFI Fuel System
Idle Speed
Screw
Throttle
Linkage
Linkage
Bushing
Damper
Spring
Figure 5B-34. Throttle Linkage/Governor Lever
Connection.
Figure 5B-33. Idle Speed Screw Details.
Initial Governor Adjustment
2. Check if the engine has a high-speed throttle stop
screw installed in the manifold casting boss. See
Figure 5B-35.
5B
The initial governor adjustment is especially critical
on EFI engines because of the accuracy and sensitivity
of the electronic control system. Incorrect adjustment
can result in overspeed, loss of power, lack of
response, or inadequate load compensation. If you
encounter any of these symptoms and suspect them to
be related to the governor setting, the following
should be used to check and/or adjust the governor
and throttle linkage.
If the governor/throttle components are all intact, but
you think there may be a problem with the
adjustment, follow Procedure A to check the setting. If
the governor lever was loosened or removed, go
immediately to Procedure B to perform the initial
adjustment.
A. Checking the Initial Adjustment
1. Unsnap the plastic linkage bushing attaching the
throttle linkage to the governor lever. See Figure
5B-34. Unhook the damper spring from the lever,
separate the linkage from the bushing, and
remove the bushing from the lever. Mark the hole
position and unhook the governor spring from
the governor lever.
High-Speed
Throttle Stop
Screw
Figure 5B-35. Throttle Details.
a. On engines with a stop screw, pivot the
throttle shaft and plate into the “Full Throttle”
position, so the tang of the throttle shaft plate
is against the end of the high-speed stop
screw. See Figure 5B-35. Temporarily clamp in
this position.
5B.23
Section 5B
EFI Fuel System
B. Setting the Initial Adjustment
1. Check the split where the clamping screw goes
through the governor lever. See Figure 5B-38.
There should be a gap of at least 1/32". If the tips
are touching and there is no gap present, the lever
should be replaced. If not already installed,
position the governor lever on the cross shaft, but
leave the clamping screw loose.
Figure 5B-36. Inserting Feeler Gauge (Engines
Without Stop Screw).
b. On engines without a stop screw, pivot the
throttle shaft and plate assembly into the
“Full Throttle” position. Insert a 1.52 mm
(0.060 in.) feeler gauge between the
tang of the throttle shaft plate and the
underside of the manifold boss. Use a
locking pliers (needle nose works best) to
temporarily clamp the parts in this position.
See Figure 5B-36.
3. Rotate the governor lever and shaft
counterclockwise until it stops. Use only enough
pressure to hold it in that position.
4. Check how the end of the throttle linkage aligns
with the bushing hole in the governor lever. See
Figure 5B-37. It should fall in the center of the
hole. If it doesn’t, perform the adjustment
procedure as follows.
Figure 5B-38. Checking ‘‘Split’’ of Clamp.
2. Follow the instructions in Step 2 of ‘‘Checking the
Initial Adjustment,’’ then reattach the throttle
linkage to the governor lever with the bushing
clip. It is not necessary to reattach the damper or
governor springs at this time.
3. Insert a nail into the hole in the top of the cross
shaft. Using light pressure, rotate the governor
shaft counterclockwise as far as it will turn, then
torque the hex nut on the clamping screw to
6.8 N·m (60 in. lb.). See Figure 5B-39. Make sure
that the governor arm has not twisted up or
down after the nut has been tightened.
Figure 5B-37. Throttle Link in Center of Hole.
Figure 5B-39. Adjusting Governor Shaft.
5B.24
Section 5B
EFI Fuel System
4. Verify that the governor has been set correctly.
With the linkage still retained in the “Full
Throttle” position (Step 2), unsnap the bushing
clip, separate the linkage from the bushing, and
remove the bushing from the lever. Follow Steps
3 and 4 in ‘‘Checking the Initial Adjustment’’.
5. Reconnect the dampening spring into its
governor lever hole from the bottom. Reinstall
the bushing and reattach the throttle linkage. See
Figure 5B-34. Reattach the governor spring in the
marked hole.
6. Start the engine and allow it to fully warm up
and establish closed loop operation
(approximately 5-10 min.). Check the speed
settings and adjust as necessary, first the low idle
speed, and then the high-speed setting.
Troubleshooting
General
When troubleshooting a problem on an engine with
EFI, basic engine operating problems must be
eliminated first before faulting the EFI system
components. What appears to be an EFI problem
could be something as simple as a fuel tank with
debris in the bottom or a plugged vent. Be sure the
engine is in good mechanical operating condition and
all other systems are operating properly before
attempting to troubleshoot the EFI system.
Troubleshooting Guide
Engine starts hard or fails to start when cold
1. Fuel pump not running
2. Faulty spark plugs
3. Old/stale fuel
4. Incorrect fuel pressure
5. Speed sensor loose or faulty
6. TPS offset incorrect (initialization)
7. TPS faulty
8. Engine temp sensor faulty
9. Faulty coils
10. Low system voltage
11. Faulty injectors
Engine starts hard or fails to start when hot
1. Faulty spark plugs
2. Fuel pump not running
3. Fuel pressure low
4. Insufficient fuel delivery
5. TPS offset incorrect (Initialization)
6. Speed sensor loose or faulty
7. TPS faulty
8. Engine temp sensor faulty
9. Faulty injectors
Engine stalls or idles roughly (cold or warm)
1. Faulty spark plugs
2. Insufficient fuel delivery
3. TPS offset incorrect
4. TPS faulty
5. Faulty engine temperature sensor
6. Faulty injectors
Engine misses, hesitates, or stalls under load
1. Fuel injector(s), fuel filter, fuel line, or fuel pickup dirty/restricted
2. Dirty air cleaner
3. Insufficient fuel pressure or fuel delivery
4. Vacuum (intake air) leak
5. Improper governor setting, adjustment or
operation
6. Speed sensor malfunction
7. TPS faulty, mounting problem or "TPS
Initialization Procedure" incorrect
8. Bad coil(s), spark plug(s), or wires
Low Power
1. Faulty/malfunctioning ignition system
2. Dirty air filter
3. Insufficient fuel delivery
4. Improper governor adjustment
5. Plugged/restricted exhaust
6. One injector not working
7. Basic engine problem exists
8. TPS faulty or mounting exists
9. Throttle plates in throttle body/intake manifold
not fully opening to WOT stop (if so equipped)
5B.25
5B
Section 5B
EFI Fuel System
Electrical System
The EFI system is a 12 VDC negative ground system,
designed to operate down to a minimum of 7.0 volts.
If system voltage drops below this level, the operation
of voltage sensitive components such as the ECU, fuel
pump, and injectors will be intermittent or disrupted,
causing erratic operation or hard starting. A fully
charged, 12 volt battery with a minimum of 350 cold
cranking amps is important in maintaining steady and
reliable system operation. Battery condition and state
of charge should always be checked first when
troubleshooting an operational problem.
Keep in mind that EFI-related problems are more
often caused by the wiring harness or connections
than by the EFI components. Even small amounts of
corrosion or oxidation on the terminals can interfere
with the milliamp currents used in system operation.
Cleaning the connectors and grounds will solve
problems in many cases. In an emergency situation,
simply disconnecting and reconnecting the connectors
may clean up the contacts enough to restore operation,
at least temporarily.
If a fault code indicates a problem with an electrical
component, disconnect the ECU connector and test for
continuity between the component connector
terminals and the corresponding terminals in the ECU
connector using an ohmmeter. Little or no resistance
should be measured, indicating that the wiring of that
particular circuit is OK. An illustrated listing of
numerical terminal locations, for each style of ECU
connector is provided on pages 5B.26 and 5B.29.
NOTE: When performing voltage or continuity tests,
avoid putting excessive pressure on or
against the connector pins. Flat pin probes
are recommended for testing to avoid
spreading or bending the terminals.
“24 Pin” (MSE 1.0) Plastic-Cased ECU Systems
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
5B.26
Function
Permanent Battery Voltage
Switched Ignition Voltage
Safety Switch
Throttle Position Sensor (TPS) and Temperature Sensor Ground
Not Used
Oil Temperature Sensor Input
Not Used
Throttle Position Sensor (TPS) Input
Speed Sensor Input
Speed Sensor Ground
Oxygen Sensor Input
Not Used (Oxygen Sensor Ground if needed)
Diagnostic Line
Throttle Position Supply Voltage
Battery Ground
Injector 1 Output
Injector 2 Output
Main Relay Output
Malfunction Indicator Light (MIL)
Not Used (Tach Output if needed)
Not Used
Ignition Coil #1 Output
Ignition Coil #2 Output
TPS Initialization Terminal
1
13
2
14
3
15
4
16
5
17
6
18
7
19
8
20
9
21
10
22
11
23
12
24
Section 5B
EFI Fuel System
“32 Pin” (MSE 1.1) Plastic-Cased ECU Systems
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
Function
Permanent Battery Voltage
Switched Battery Voltage
TPS Set; “Auto-Learn” Initialization Terminal
Throttle Position Sensor (TPS) and Temperature Sensor Ground
Not Used
Oil Temperature Sensor Input
Not Used
Throttle Position Sensor (TPS) Input
Speed Sensor Input (+)
Speed Sensor Ground (-)
Not Used
Not Used
Not Used
Injector 1 Output
Injector 2 Output
Not Used
Diagnostic Line
Throttle Position Sensor Supply Voltage
Battery Ground
Oxygen Sensor Input
Battery Ground (secondary)
Not Used
Not Used
Not Used
Safety Switch Input
Not Used
Not Used
Main Relay Output
Malfunction Indicator Light (MIL)
Ignition Coil #1 Output
Ignition Coil #2 Output
Not Used
1
17
2
18
3
19
4
20
5
21
6
22
7
23
8
24
9
25
10
26
11
27
12
28
13
29
14
30
15
31
16
32
5B
5B.29
Section 5B
EFI Fuel System
Fuel System
WARNING: Fuel System Under Pressure!
The fuel system operates under high pressure. System
pressure must be relieved through the test valve in the fuel
rail prior to servicing or removal of any fuel system
components. Do not smoke or work near heaters or other fire
hazards. Have a fire extinguisher handy and work only in a
well-ventilated area.
The function of the fuel system is to provide sufficient
delivery of fuel at the system operating pressure of 39
psi ± 3. If an engine starts hard, or turns over but will
not start, it may indicate a problem with the EFI fuel
system. A quick test will verify if the system is
operating.
Fault Codes
The ECU continuously monitors engine operation
against preset performance limits. If the operation is
outside the limits, the ECU activates the MIL and
stores a diagnostic code in its fault memory. If the
component or system returns to proper function, the
ECU will eventually self-clear the fault code and turn
off the MIL. If the MIL stays illuminated, it warns the
customer that dealer service is required. Upon receipt,
the dealer technician can access the fault code(s) to
help determine what portion of the system is
malfunctioning. The 2-digit fault codes available based
upon the style of ECU are listed on pages 5B.31-5B.32.
The codes are accessed through the key switch and
displayed as blinks or flashes of the MIL. Access the
codes as follows:
1. Disconnect and ground the spark plug leads.
1. Start with the key switch off.
2. Complete all safety interlock requirements and
crank the engine for approximately 3 seconds.
3. Remove the spark plugs and check for fuel at the
tips.
a. If there is fuel at the tips of the spark plugs the
fuel pump and injectors are operating.
b. If there is no fuel at the tips of the spark plugs,
check the following:
1) Make sure the fuel tank contains clean,
fresh, proper fuel.
2) Make sure that the vent in the fuel tank is
open.
3) Make sure the fuel tank valve (if so
equipped) is fully opened.
4) Make sure the battery is supplying proper
voltage.
5) Check that the fuses are good, and that
no electrical or fuel line connections are
damaged or broken.
6) Test fuel pump and relay operation as
described earlier under ‘‘Fuel Pump –
Service.’’
5B.30
2. Turn the key switch on-off-on-off-on, leaving it
on in the third sequence. The time between
sequences must be less than 2.5 seconds.
3. Any stored fault codes will then be displayed as a
series of MIL blinks (from 2 to 6) representing the
first digit, followed by a pause, and another series
of blinks (from 1 to 6) for the second digit (see
Figure 5B-40).
a. It’s a good idea to write down the codes as
they appear, as they may not be in numerical
sequence.
b. Code 61 will always be the last code
displayed, indicating the end of code
transmission. If code 61 appears immediately,
no other fault codes are present.
Section 5B
EFI Fuel System
Example of Diagnostic Display
1. Diagnostic display initiated through ignition key sequencing.
2.
Long Pause
Short Pause
3.
Code 32
3
4.
2
Long Pause
5.
Code 61
6
1
6.
Long Pause
7.
Light remains on at end of transmission
Figure 5B-40.
5B
After the problem has been corrected, the fault codes may be cleared as follows.
1. Disconnect the negative (-) battery cable or the main harness connector for one minute.
2. Reconnect the cable and tighten securely. Start the engine and allow it to run for several minutes. The MIL
should remain off if the problem was corrected, and the fault codes should not reappear (codes 31, 32, 33,
and 34 may require 10-15 minutes of running to reappear).
The following chart lists the fault codes, what they correspond to, and what the visual indications will be.
Following the chart is a list of the individual codes with an explanation of what triggers them, what symptoms
might be expected, and the probable causes.
Diagnostic Code Summary
Blink
C ode
OBD2
P-Code
Applicable
to: "32 Pin" Connection or Failure Description
(MSE 1.1)
ECU/System Only
"24 Pin"
(MSE 1.0)
Plastic-Cased
ECU/System
"32 Pin"
(MSE 1.1)
Plastic-Cased
ECU/System
No RPM Signal
Y
Y
Note
-
-
21
P 0335
Loss of Synchronization
Y
Y
22
P 0120
TPS - Signal Implausible
N
N
22
P 0122
TPS - Open or Short Circuit to Ground
Y
Y
22
P 0123
TPS - Short Circuit to Battery
Y
Y
23
P 0601
Defective ECU
Y
Y
Engine Speed Sensor
Y
Y
9
System too Lean
Y
Y
6
24
31
P 0174
2
Continue on next page.
5B.31
Section 5B
EFI Fuel System
Diagnostic Code Summary cont.
Blink
C ode
OBD2
P-Code
Applicable
to: "32 Pin" Connection or Failure Description
(MSE 1.1)
ECU/System Only
"24 Pin"
(MSE 1.0)
Plastic-Cased
ECU/System
"32 Pin"
(MSE 1.1)
Plastic-Cased
ECU/System
Note
31
P 0132
O2 Sensor Circuit: Shorted to Battery
N
Y
3
32
P 0134
O2 Sensor Circuit: No Activity Detected
N
N
8
33
P 0175
System too Rich
Y
Y
7,8
33
P 0020
O2 Sensor Control at Upper Limit
Y
Y
8
34
P 0171
Maximum Adaption Limit Reached
Y
Y
8
34
P 0172
Minimum Adaption Limit Reached
Y
Y
8
42
P0117
Temperature Sensor Circuit: Shorted to
Ground
Y
Y
42
P0118
Temperature Sensor Circuit: Open Circuit or
Short to Battery
Y
Y
43
N/A
Failure Completing Autolearn - TPS Offset
below minimum allowable limit
N/A
Y
44
N/A
Failure Completing Autolearn - TPS offset
above maximum allowable limit
N/A
Y
51
P 1260
Injector 1 - Open Circuit
N/A
Y
51
P 0261
Injector 1 - Short Circuit to Ground
N/A
Y
51
P 0262
Injector 1 - Short Circuit to Battery
N/A
Y
52
P 1263
Injector 2 - Open Circuit
N/A
Y
52
P 0264
Injector 2 - Short Circuit to Ground
N/A
Y
52
P 0265
Injector 2 - Short Circuit to Battery
N/A
Y
55
91651
Diagnostic Lamp - Open Circuit
N/A
Y
55
P 1652
Diagnostic Lamp - Short Circuit to Ground
N/A
Y
55
P 1653
Diagnostic Lamp - Short Circuit to Battery
N/A
Y
56
P 1231
Pump Relay - Open Circuit
N/A
Y
56
P 1232
Pump Relay - Short Circuit to Ground
N/A
Y
56
P 1233
Pump Relay - Short Circuit to Battery
N/A
Y
Y
Y
61
End of Code Transmission
Note:
1. Idle Switch not used.
2. Diagnostic of "TPS - Signal Implausible" is disabled in code.
3. "O2 Sensor Short to Battery" diagnostic detection is disabled with SAS fuel-cutoff calibrated out.
4. Air Temperature Sensor not used.
5. "Temperature Sensor Signal Implausible": diagnostic detection is calibrated out, with TPLAUS set to -50°C.
6. System too Lean used to be "O2 Sensor - Short to Ground (P0131)."
7. "System too Rich" used to be "O2 Sensor Control at Lower Limit (P0019)."
8. Obtainable only with ECU 24 584 28-S or later.
9. Will not blink out.
5B.32
Section 5B
EFI Fuel System
Code:
Source:
Explanation:
21
Engine Speed Sensor
ECU receiving inconsistent tooth
count signals from speed sensor.
Expected Engine
Response:
Possible misfire as ECU attempts
to resynchronize during which time
fuel and spark calculations are not
made.
Possible Causes:
1. Engine Speed Sensor Related
a. Sensor connector or wiring.
b. Sensor loose or incorrect air gap.
c. Flywheel key sheared.
2. Speed Sensor Ring Gear Related
a. Damaged teeth.
b. Varying gap (gear loose/out of alignment).
3. Engine Wiring Harness Related
“24 Pin” (MSE 1.0) Plastic-Cased ECU:
a. Pin circuits 9 and/or 10 wiring or connectors.
b. Shielding for pin circuits 9 and/or 10 damaged
or not properly grounded.
c. Poor or improper grounds in system (battery,
ECU oxygen sensor, shielding, fuel pump,
ignition output).
d. Pin circuits 9 and/or 10 routed near noisy
electrical signals (coils, spark plug lead, plug
connector).
3. Engine Wiring Harness Related
“32 Pin” (MSE 1.1) Plastic-Cased ECU:
a. Pin circuits 9 and/or 10 wiring or connectors.
b. Shielding for pin circuits 9 and/or 10 damaged
or not properly grounded.
c. Poor or improper grounds in system (battery,
ECU, oxygen sensor, shielding, fuel pump,
ignition output).
d. Pin circuits 9 and/or 10 routed near noisy
electrical signals (coils, spark plug lead, plug
connector).
4. ECU/Harness Related
a. ECU-to-harness connection problem.
5. Ignition System Related
a. Non-resistor spark plug(s) used.
Code:
Source:
Explanation:
22
Throttle Position Sensor (TPS)
Unrecognizable signal is being sent
from sensor (too high, too low,
inconsistent).
Expected Engine
Response:
A “limp-home” operating mode
occurs, with an overall decrease in
operating performance and efficiency.
Fuel delivery is based upon the
oxygen sensor and five mapped
values only. Rich running (black
smoke) will occur until “closed loop”
operation is initiated. A stumble or
misfire on hard acceleration and/or
erratic operation may be exhibited.
Possible Causes:
1. TPS Sensor Related
a. Sensor connector or wiring.
b. Sensor output affected or disrupted by dirt,
grease, oil, wear, or breather tube position
(must be to side opposite the TPS).
c. Sensor loose on throttle body manifold.
2. Throttle Body Related
a. Throttle shaft or bearings worn/damaged.
3. Engine Wiring Harness Related
“24 Pin” (MSE 1.0) Plastic-Cased ECU:
a. Pin circuits 4, 8, and/or 14 damaged (wiring,
connectors).
b. Pin circuits 4, 8, and/or 14 routed near noisy
electrical signal (coils, alternator).
c. Intermittent 5 volt source from ECU (pin
circuit 14).
3. Engine Wiring Harness Related
“32 Pin” (MSE 1.1) Plastic-Cased ECU:
a. Pin circuits 4, 8, and/or 18 damaged (wiring,
connectors).
b. Pin circuits 4, 8, and/or 18 routed near noisy
electrical signal (coils, alternator).
c. Intermittent 5 volt source from ECU (pin
circuit 18).
4. ECU/Harness Related
a. ECU-to-harness connection problem.
5B.33
5B
Section 5B
EFI Fuel System
If the engine is still running rich
(laboring, short on power) or lean
popping or misfiring), the fuel
mixture is suspect, probably incorrect
TPS initialization or low fuel pressure.
Code:
Source:
Explanation:
23
ECU
ECU is unable to recognize or process
signals from its memory.
Expected Engine
Response:
Engine will not run.
Possible Causes:
1. ECU (internal memory problem).
a. Diagnosable only through the elimination of
all other system/component faults.
Code:
Source:
Explanation:
24 (Will not blink out)
Engine Speed Sensor
No tooth signal from speed sensor.
MIL light will not go out when
cranking.
Expected Engine
Response:
None-engine will not start or run as
the ECU is unable to estimate speed.
Possible Causes:
1. Engine Speed Sensor Related
a. Sensor connector or wiring.
b. Sensor loose or air gap incorrect.
2. Speed Sensor Wheel Related
a. Damaged teeth.
b. Gap section not registering.
3. Engine Wiring Harness Related
a. Pin circuit wiring or connectors.
Pin(s) 9 and/or 10 for “24 Pin” (MSE 1.0)
Plastic-Cased ECU.
Pin(s) 9 and/or 10 for “32 Pin” (MSE 1.1)
Plastic-Cased ECU.
4. ECU/Harness Related
a. ECU-to-harness connection problem.
Code:
Source:
Explanation:
31
Fuel Mixture or Oxygen Sensor
“System too lean.” Oxygen sensor not
sending expected voltage to ECU.
Expected Engine
Response:
System operates under “open loop”
control only. Until fault is detected
and registered by ECU, engine will
run richif oxygen sensor is shorted to
ground or lean if it is shorted to
battery voltage. After fault is detected,
performance can vary, depending on
cause. If performance is pretty good,
the problem is probably with the
oxygen sensor, wiring, or connectors.
5B.34
Possible Causes:
1. TPS Initialization Incorrect
a. Lean condition (check oxygen sensor signal
with VOA and see Oxygen Sensor section).
2. Engine Wiring Harness Related
a. Pin circuit wiring or connectors.
Pin 11 for “24 Pin” (MSE 1.0) Plastic-Cased
ECU.
Pin 20 for “32 Pin” (MSE 1.1) Plastic-Cased
ECU.
3. Low Fuel Pressure
4. Oxygen Sensor Related
a. Sensor connector or wiring problem.
b. Exhaust leak.
c. Poor ground path to engine (sensor is case
grounded).
5. Poor system ground from ECU to engine, causing
rich running while indicating lean.
Code:
Source:
Explanation:
32
Oxygen Sensor
No change in the sensor output
signal.
Expected Engine
Response:
“Open loop” operation only, may
cause a drop in system performance
and fuel efficiency.
Possible Causes:
1. Engine Wiring Harness Related
a. Pin circuit 11 wiring or connectors.
Pin 11 for “24 Pin” (MSE 1.0) Plastic-Cased
ECU.
Pin 20 for “32 Pin” (MSE 1.1) Plastic-Cased
ECU.
2. Oxygen Sensor Related
a. Sensor connector or wiring problem.
b. Sensor contaminated or damaged.
c. Sensor below the minimum operating
temperature (375°C, 709°F).
d. Poor ground path from sensor to engine
(sensor grounds through shell, see Oxygen
Sensor section).
Section 5B
EFI Fuel System
Code:
Source:
Explanation:
33
Oxygen Sensor/Fuel System
“System too Rich” Temporary fuel
adaptation control is at the upper
limit.
Expected Engine
Response:
Erratic performance. Will run rich
(smoke).
Possible Causes:
1. Fuel Supply Related (nothing lean – only rich)
a. Restricted return line causing excessive fuel
pressure.
b. Fuel inlet screen plugged (in-tank fuel pump
only).
c. Incorrect fuel pressure at fuel rail.
2. Oxygen Sensor Related
a. Sensor connector or wiring problem.
b. Sensor contaminated or damaged.
c. Exhaust leak.
d. Poor ground path.
e. Pin circuit wiring or connectors.
Pin 11 for “24 Pin” (MSE 1.0) Plastic-Cased
ECU.
Pin 20 for “32 Pin” (MSE 1.1) Plastic-Cased
ECU.
3. TPS Sensor Related
a. Throttle plate position incorrectly set or
registered during “Initialization.’’
b. TPS problem or malfunction.
4. Engine Wiring Harness Related
a. Difference in voltage between sensed voltage
(pin circuit 17 for metal-cased ECU, pin
circuit 2 for plastic-cased ECU) and actual
injector voltage (circuit 45/45A).
5. Systems Related
a. Ignition (spark plug, plug wire, ignition coil.
b. Fuel (fuel type/quality, injector, fuel pump,
fuel pressure.
c. Combustion air (air cleaner dirty/restricted,
intake leak, throttle bores).
d. Base engine problem (rings, valves).
e. Exhaust system leak.
f. Fuel in the crankcase oil.
g. Blocked or restricted fuel return circuit to
tank.
Code:
Source:
34
Oxygen Sensor/Fuel System
Components
Explanation: Long term fuel adaptation control is
at the upper or lower limit.
Expected Engine
Response:
System operates “closed loop.” No
appreciable performance loss as long
as the temporary adaptation can
provide sufficient compensation.
Possible Causes:
1. Oxygen Sensor Related
a. Sensor connector or wiring.
b. Sensor contaminated or damaged.
c. Exhaust leak.
d. Poor ground path.
e. Pin circuit wiring or connectors.
Pin 11 for “24 Pin” (MSE 1.0) Plastic-Cased
ECU.
Pin 20 for “32 Pin” (MSE 1.1) Plastic-Cased
ECU.
2. TPS Sensor Related
a. Throttle plate position incorrect during
“Initialization” procedure.
b. TPS problem or malfunction.
3. Engine Wiring Harness Related
a. Difference in voltage between sensed voltage
(pin circuit 2) and actual injector voltage
(circuit 45/45A).
b. Problem in wiring harness.
c. ECU-to-harness connection problem.
4. Systems Related
a. Ignition (spark plug, plug wire, ignition coil).
b. Fuel (fuel type/quality, injector, fuel pressure,
fuel pump).
c. Combustion air (air cleaner dirty/restricted,
intake leak, throttle bores).
d. Base engine problem (rings, valves).
e. Exhaust system leak (muffler, flange, oxygen
sensor mounting boss, etc.).
f. Fuel in the crankcase oil.
g. Altitude.
h. Blocked or restricted fuel return circuit to
tank.
6. ECU Related
a. ECU-to-harness connection problem.
5B.35
5B
Section 5B
EFI Fuel System
Code:
42
Source:
Engine (Oil) Temperature Sensor
Explanation: Not sending proper signal to ECU.
Expected Engine
Response:
Engine will be hard to start because
ECU can’t determine correct fuel
mixture.
Possible Causes:
1. Temperature Sensor Related
a. Sensor wiring or connection.
2. Engine Wiring Harness Related
"24 Pin" (MSE 1.0) Plastic-Cased ECU:
a. Pin circuits 4, 6 and/or 4A damaged (wires,
connectors) or routed near noisy signal (coils,
alternator, etc.).
b. ECU-to-harness connection problem.
2. Engine Wiring Harness Related
"32 Pin" (MSE 1.1) Plastic-Cased ECU:
a. Pin circuits 4, 6 and/or 4A damaged (wires,
connectors) or routed near noisy signal (coils,
alternator, etc.).
b. ECU-to-harness connection problem.
2. Engine Wiring Harness Related
a. Broken or shorted wire in harness.
ECU pin 18 to TPS pin 1.
ECU pin 4 to TPS pin 2.
ECU pin 8 to TPS pin 3.
3. Throttle Body Related
a. Throttle shaft inside TPS worn, broken, or
damaged.
b. Throttle plate loose or misaligned.
c. Throttle plate bent or damaged allowing extra
airflow past, or restricting movement.
4. ECU Related
a. Circuit providing voltage or ground to TPS
damaged.
b. TPS signal input circuit damaged.
5. Oxygen Sensor/Harness Related.
a. Oxygen sensor bad.
b. Wiring problem to oxygen sensor.
c. Muffler leak (causing O2 sensor to falsely
indicate a lean condition).
d. Bad ground between ECU and engine.
Code:
3. System Related
a. Engine is operating above the 176°C (350°F)
temperature sensor limit.
Code:
43 and 44
“32 Pin” (MSE 1.1)
Plastic-Cased ECU only.
Source:
TPS “Auto-Learn” initialization
function failed, throttle angle out of
learning range.
Explanation: While performing the TPS “AutoLearn” function, the measured
throttle angle was not within
acceptable limits.
Expected Engine
Response:
MIL illuminated. Engine will continue
to run but not properly. Upon restart
TPS Auto-Learn function will run
again unless voltage to ECU
disconnected to clear memory.
Possible Causes:
1. TPS Related
a. TPS rotated on throttle shaft assembly out of
allowable range.
b. TPS bad.
5B.36
51
“32 Pin” (MSE 1.1) PlasticCased ECU only.
Source:
Injector #1 circuit open, shorted to
ground, or shorted to battery.
Explanation: Injector #1 is not functioning because
the circuit is open, shorted to ground,
or shorted to battery.
Expected Engine
Response:
Engine will run very poorly with only
one cylinder functioning.
Possible Causes:
1. Injector Related
a. Injector coil shorted or opened.
2. Engine Wiring Harness Related
a. Broken or shorted wire in harness.
ECU pin 14 to injector pin 2. ECU pin 28 to
fuel pump relay pin 86. Note: after key-off
then key-on, code 56 would be set also. Fuel
pump relay pin 87 to injector pin 1.
b. Open main fuse F1.
Section 5B
EFI Fuel System
3. Fuel Pump Relay Related
a. Bad fuel pump relay.
Primary side functional but pin 30 to pin 87
remains open. Primary side pin 85 to pin 86 is
either open, or shorted during engine
operation. Note: after key-off then key-on,
code 56 would be set also.
4. ECU Related
a. Circuit controlling injector #1 damaged.
b. Circuit controlling fuel pump relay damaged.
Code:
52
“32 Pin” (MSE 1.1) PlasticCased ECU only.
Source:
Injector #2 circuit open, shorted to
ground,or shorted to battery.
Explanation: Injector #2 is not functioning because
the circuit is open, shorted to ground,
or shorted to battery.
Expected Engine
Response:
Engine will run very poorly with only
one cylinder functioning.
Possible Causes:
1. Injector Related
a. Injector coil shorted or opened.
2. Engine Wiring Harness Related
a. Broken or shorted wire in harness.
ECU pin 15 to injector pin 2.
ECU pin 28 to fuel pump relay pin 86. Note:
after key-off then key-on code 56 would be set
also. Fuel pump relay pin 87 to injector pin 1.
b. Opened main fuse F1.
3. Fuel Pump Relay Related
a. Bad fuel pump relay.
Primary side functional, but pin 30 to pin 87
remains open. Primary side pin 85 to pin 86 is
open or shorted during engine operation.
Note: after key-off then key-on code 56 would
be set also.
4. ECU Related
a. Circuit controlling injector #2 damaged.
b. Circuit controlling fuel pump relay damaged.
Code:
Source:
Explanation:
“32 Pin” (MSE 1.1) PlasticCased ECU only.
MIL (Diagnostic lamp) circuit open,
shorted to ground, or shorted to
battery.
MIL is not functioning because the
circuit is open, shorted to ground, or
shorted to battery.
Expected Engine
Response:
Engine will run normally if no other
errors are present.
Possible Causes:
1. MIL (diagnostic lamp) Related
a. MIL element opened or element shorted to
ground.
b. Lamp missing.
2. Engine Wiring Harness Related
a. Broken or shorted wire in harness.
ECU pin 29 to lamp open or shorted.
3. Vehicle Wiring Harness Related
a. Broken or shorted wire in harness.
Power lead to MIL open or shorted.
4. ECU related
a. Circuit controlling lamp damaged.
Code:
56
“32 Pin” (MSE 1.1) PlasticCased ECU only.
Source:
Fuel pump relay circuit open, shorted
to ground, or shorted to battery.
Explanation: Fuel pump, ignition coils, and fuel
injectors will not function because the
fuel pump relay circuit is either open,
shorted to ground, or may be “on”
continuously if shorted to battery.
Expected Engine
Response:
Engine will not run, or fuel pump will
continue to run when switch is off.
Possible Causes:
1. Fuel Pump Relay Related
a. Bad fuel pump relay.
Primary side open or shorted.
2. Fuel Pump Related
a. Fuel pump open or shorted internally.
3. Engine Wiring Harness related
a. Fuel pump fuse F1 open.
b. Broken or shorted wire in harness.
ECU pin 28 to fuel pump relay pin 86.
Ignition switch to fuel pump relay pin 85.
55
4. ECU Related
a. Circuit controlling fuel pump relay damaged.
5B.37
5B
Section 5B
EFI Fuel System
Code:
Source:
Explanation:
5B.38
61
Denotes the end of fault codes. If
signaled first, no other fault codes
are present.
Troubleshooting Flow Chart
The following flow chart provides an alternative
method of troubleshooting the EFI system. The chart
will enable you to review the entire system in about
10-15 minutes. Using the chart, the accompanying
diagnostic aids (listed after the chart), and any
signaled fault codes, you should be able to quickly
locate any problems within the system.
Section 5B
EFI Fuel System
5B
*Operate for an appropriate period of time based upon original fault codes.
Figure 5B-41.
5B.39
Section 5B
EFI Fuel System
Flow Chart Diagnostic Aids
Diagnostic Aid #1 “SYSTEM POWER” (MIL does not
illuminate when key is turned “on”)
Possible causes:
1. Battery
2. Main system fuse
3. MIL light bulb burned out
4. MIL electrical circuit problem
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Pin
circuits 19 and 84.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Pin
circuits 29 and 84.
5. Ignition switch
6. Permanent ECU power circuit problem
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Pin
circuit 1.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Pin
circuit 1.
7. Switched ECU power circuit problem
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Pin
circuit 2.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Pin
circuit 2.
8 ECU grounds
9. ECU
Diagnostic Aid #2 “FAULT CODES” (Refer to
detailed fault code listing before flow chart and
“servicing” information for the respective
components)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
Code 21 - Engine Speed Synchronization
Code 22 - Throttle Position Sensor (TPS)
Code 23 - Engine Control Unit (ECU)
Code 31 - Oxygen Sensor
Code 32 - Oxygen Sensor
Code 33 - Fuel System (temporary adaptation
factor)
Code 34 - Fuel System (permanent adaptation
factor)
Code 42 - Engine (Oil) Temperature Sensor
Code 43 - TPS “Auto-Learn” Initialization
Function (Below Min. Limit), “32 Pin” (MSE 1.1)
Plastic-Cased ECU only.
Code 44 - TPS “Auto-Learn” Initialization
Function (Above Max. Limit), “32 Pin” (MSE 1.1)
Plastic-Cased ECU only.
Code 51 - Injector 1, “32 Pin” (MSE 1.1) PlasticCased ECU only.
Code 52 - Injector 2, “32 Pin” (MSE 1.1) PlasticCased ECU only.
Code 55 - MIL Light, “32 Pin” (MSE 1.1) PlasticCased ECU only.
5B.40
14. Code 56 - Pump Relay, “32 Pin” (MSE 1.1)
Plastic-Cased ECU only.
15. Code 61 - End of Fault/Blink Code Transmission
Diagnostic Aid #3 “RUN/ON” (MIL remains “on”
while engine is running)*
Possible causes:
1. Fault codes which turn on MIL when engine is
running.
a. Code 21 - Engine Speed Synchronization
b. Code 22 - Throttle Position Sensor (TPS)
c. Code 23 - Engine Control Unit (ECU)
d. Code 31 - Oxygen Sensor (shorted)
e. Code 34 - Fuel System (permanent adaptation
at limit)
f. Code 42 - Engine (Oil) Temperature Sensor
g. Code 43 - TPS “Auto-Learn” Initialization
Function (Below Min. Limit), “32 Pin”
(MSE 1.1) Plastic-Cased ECU only.
h. Code 44 - TPS “Auto-Learn” Initialization
Function (Above Max. Limit) “32 Pin”
(MSE 1.1) Plastic-Cased ECU only.
i. Code 51 - Injector 1, “32 Pin” (MSE 1.1)
Plastic-Cased ECU only.
j. Code 52 - Injector 2, “32 Pin” (MSE 1.1)
Plastic-Cased ECU only.
k. Code 55 - MIL Light, “32 Pin” (MSE 1.1)
Plastic-Cased ECU only.
l. Code 56 - Pump Relay, “32 Pin” (MSE 1.1)
Plastic-Cased ECU only.
2. MIL circuit grounded between light and ECU.
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Pin
circuit 19.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Pin
circuit 29.
3. ECU
*NOTE: The MIL in Plastic-Cased ECU systems must
be a 1/4 watt incandescent lamp.
Diagnostic Aid #4 “SPEED SENSOR” (MIL does not
turn off during cranking)
Possible causes:
1. Speed sensor
2. Speed sensor circuit problem
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Pin
circuits 9 and 10.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Pin
circuits 9 and 10.
3. Speed sensor/toothed wheel air gap
4. Toothed wheel
5. Flywheel key sheared
6. ECU
Section 5B
EFI Fuel System
Diagnostic Aid #5 “FUEL PUMP” (fuel pump not
turning on)
Diagnostic Aid #8 “FUEL SYSTEM-ELECTRICAL”
(no fuel delivery)
Possible causes:
1. Fuel pump fuse
2. Fuel pump circuit problem
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuits
30, 87, and relay.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuits
30, 87, and relay.
3. Fuel pump
Possible causes:
1. No fuel
2. Air in fuel rail
3. Fuel valve shut off
4. Fuel filter/line plugged
5. Injector circuit(s)
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuits
16, 17, 45, and 45A.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuits
14,15, and 45.
6. Injector
7. ECU grounds
8. ECU
Diagnostic Aid #6 “RELAY” (relay not operating)
Possible causes:
1. Safety switches/circuit(s) problem
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuit 3.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuit 25.
2. Relay circuit(s) problem
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuits
18, 85, 30, and 87.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuits
28,85, 30, and 87.
3. Relay
4. ECU grounds
5. ECU
Diagnostic Aid #7 “IGNITION SYSTEM” (no spark)
Possible causes:
1. Spark plug
2. Plug wire
3. Coil
4. Coil circuit(s)
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuits
22, 23, 65, 66, 30, and relay.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuits
30, 31, 65, 66, relay and relay circuit 30.
5. ECU grounds
6. ECU
Diagnostic Aid #9 “FUEL SYSTEM” (fuel pressure)
Possible causes for low fuel system pressure:
1. Low fuel
2. Fuel filter plugged
3. Fuel supply line plugged
4. Pressure regulator
5. Fuel pump
5B
Possible causes for high fuel system pressure:
1. Pressure regulator
2. Fuel return line plugged or restricted.
Diagnostic Aid #10 “BASIC ENGINE” (cranks but
will not run)
Possible causes:
1. Refer to basic engine troubleshooting charts
within service manual sections 3, 5, and 8.
5B.41
Section 6
Lubrication System
Section 6
Lubrication System
General
This engine uses a full pressure lubrication system,
delivering oil under pressure to the crankshaft,
camshaft, and connecting rod bearing surfaces. In
addition to lubricating the bearing surfaces, the
lubrication system supplies oil to the hydraulic valve
lifters.
A high-efficiency gerotor pump is located in the oil
pan. The oil pump maintains high oil flow and oil
pressure, even at low speeds and high operating
temperatures. A pressure relief valve in the oil pan
limits the maximum pressure of the system.
Service
The oil pan must be removed to service the oil pump
or oil pickup. Refer to the appropriate procedures in
Sections 9 and 10.
NOTE: Using other than service class SG, SH, SJ or
higher oil, or extending oil change intervals
longer than recommended can cause engine
damage.
NOTE: Synthetic oils meeting the listed
classifications may be used with oil changes
performed at the recommended intervals.
However, to allow piston rings to properly
seat, a new or rebuilt engine should be
operated for at least 50 hours using standard
petroleum based oil before switching to
synthetic oil.
A logo or symbol on oil containers identifies the API
service class and SAE viscosity grade. See Figure 6-1.
Oil Recommendations
Using the proper type and weight of oil in the
crankcase is extremely important; so is checking oil
daily and changing the oil and filter regularly.
Use high-quality detergent oil of API (American
Petroleum Institute) service class SG, SH, SJ or
higher. Select the viscosity based on the air
temperature at the time of operation as shown in the
following table.
Figure 6-1. Oil Container Logo.
**
*
The top position of the symbol shows service class
such as API SERVICE CLASS SJ. The symbol may
show additional categories such as SH, SG/CC, or
CD. The center portion shows the viscosity grade
such as SAE 10W-30. If the bottom portion shows
‘‘Energy Conserving,’’ it means that oil is intended to
improve fuel economy in passenger car engines.
*Use of synthetic oil having 5W-20 or 5W-30 rating is
acceptable, up to 4°C (40°F).
**Synthetic oils will provide better starting in extreme
cold below -23°C (-10°F).
6.1
6
Section 6
Lubrication System
Checking Oil Level
The importance of checking and maintaining the
proper oil level in the crankcase cannot be
overemphasized. Check oil BEFORE EACH USE as
follows:
1. Make sure the engine is stopped, level, and is cool
so the oil has had time to drain into the sump.
2. Clean the area around the oil fill cap/dipstick
before removing it. This will help to keep dirt,
grass clippings, etc., out of the engine.
3. Unthread and remove the oil fill cap/dipstick;
wipe oil off. Reinsert the dipstick into the tube
and rest the oil fill cap on the tube. Do not thread
the cap onto the tube. See Figure 6-2.
NOTE: To prevent extensive engine wear or damage,
always maintain the proper oil level in the
crankcase. Never operate the engine with the
oil level below the low mark or above the full
mark on the dipstick.
Changing Oil and Oil Filter
Changing Oil
Change the oil after every 100 hours of operation
(more frequently under severe conditions). Refill with
service class SG, SH, SJ or higher oil as specified in the
‘‘Viscosity Grades’’ table on page 6.1.
Change the oil while the engine is still warm. The oil
will flow more freely and carry away more
impurities. Make sure the engine is level when filling
or checking oil.
Oil Drain
Figure 6-2. Oil Fill Cap/Dipstick.
4. Remove dipstick and check oil level. The level
should be between the FULL and ADD marks. If
low, add oil of the proper type up to the full
mark. Reinstall oil fill cap/dipstick and thread
tight.
Figure 6-4. Oil Drain Plug (Starter Side).
"Full" Mark
Operating
Range
Oil Filter
Oil Drain
Figure 6-5. Oil Drain Plug (Oil Filter Side).
Figure 6-3. Oil Level Marks on Dipstick.
6.2
Section 6
Lubrication System
Change the oil as follows:
1. A drain plug is located on either side of the oil
sump; one is near the starter, the other is near the
oil filter. See Figures 6-4 and 6-5. Clean the area
around the most accessible oil drain plug and the
oil fill cap/dipstick.
2. Remove the selected drain plug and the oil fill
cap/dipstick.
3. Allow the oil to drain and then reinstall the
drain plug. Torque to 13.6 N·m (10 ft. lb.).
4. Fill the engine with the proper oil to the ‘‘FULL’’
mark on the dipstick. Always check the oil level
with the dipstick before adding more oil.
5. Reinstall the oil fill cap/dipstick.
Changing Oil Filter
Replace the oil filter at least every other oil change
(every 200 hours of operation). Always use a genuine
Kohler oil filter. Change the filter as follows. See
Figures 6-4 or 6-5.
8. Fill the engine with the proper oil to the “FULL”
mark on the dipstick. Always check the oil level
with the dipstick before adding more oil.
9. Reinstall the oil fill cap/dipstick.
10. Start the engine and check for oil leaks. Stop the
engine, correct any leaks, and allow a minute for
the oil to drain down, then recheck the level on
the dipstick.
Service Oil Cooler
Some engines are equipped with an oil cooler. One
style of oil cooler mounts on the engine crankcase and
has the oil filter on it. See Figure 6-6. The other style of
oil cooler is mounted on the blower housing, separate
from the oil filter. See Figure 6-7.
Inspect and clean the oil cooler every 100 hours of
operation (more frequently under severe conditions).
In order to be effective, the oil cooler must be kept free
of debris.
1. An oil drain plug is located on either side of the
oil sump; one is next to the oil filter, the other is
next to the starter. Clean the areas around the
most accessible drain plug, the oil filter, and the
oil fill cap/dipstick.
2. Remove the selected drain plug and the oil fill
cap/dipstick.
3. Allow the oil to drain and then reinstall the
drain plug. Torque to 13.6 N·m (10 ft. lb.).
4. Remove the old filter and wipe off the filter
adapter with a clean cloth.
Figure 6-6. Crankcase Mounted Oil Cooler.
To service the crankcase mounted oil cooler, clean off
the outside fins with a brush or with compressed air.
5. Place a new replacement filter in a shallow pan
with the open end up. Pour new oil, of the proper
type, in through the threaded center hole. Stop
pouring when the oil reaches the bottom of the
threads. Allow a minute or two for the oil to be
absorbed by the filter material.
6. Apply a thin film of clean oil to the rubber gasket
on the new oil filter.
7. Install the new oil filter to the filter adapter.
Hand tighten the filter clockwise until the rubber
gasket contacts the adapter, then tighten the
filter an additional 3/4-1 turn.
Figure 6-7. Blower Housing Mounted Oil Cooler.
6.3
6
Section 6
Lubrication System
To service the blower housing mounted oil cooler,
clean the outside of the fins with a brush (see Figure
6-7). Remove the two screws holding the cooler unit
to the blower housing. Tilt the cooler downward as
shown in Figure 6-8. Clean the inside of the cooler
with a brush or with compressed air. After cleaning,
reinstall the oil cooler to the blower housing with the
two mounting screws.
Oil
Sentry™
Figure 6-9. Oil Sentry™ Location.
On engines not equipped with Oil Sentry™ the
installation hole is sealed with a 1/8-27 N.P.T.F. pipe
plug.
Figure 6-8. Cleaning Blower Housing Mounted Oil
Cooler.
Oil Sentry™
To install the switch, follow these steps:
1. Apply pipe sealant with Teflon® (Loctite® No.
59241 or equivalent) to the threads of the switch.
2. Install the switch into the tapped hole in the
breather cover. See Figure 6-9.
3. Torque the switch to 4.5 N·m (40 in. lb.).
General
Some engines are equipped with an optional Oil
Sentry™ oil pressure monitor switch. If the oil
pressure drops below an acceptable level, the Oil
Sentry™ will either shut off the engine or activate a
warning signal, depending on the application.
The pressure switch is designed to break contact as
the oil pressure increases above 3-5 psi, and make
contact as the oil pressure decreases below 3-5 psi.
On stationary or unattended applications (pumps,
generators, etc.), the pressure switch can be used to
ground the ignition module to stop the engine. On
vehicular applications (lawn tractors, mowers, etc.)
the pressure switch can only be used to activate a
“low oil” warning light or signal.
NOTE: Make sure the oil level is checked before each
use and is maintained up to the “FULL”
mark on the dipstick. This includes engines
equipped with Oil Sentry™.
Installation
The Oil Sentry™ pressure switch is installed into the
breather cover. See Figure 6-9.
6.4
Testing the Switch
Compressed air, a pressure regulator, pressure gauge
and a continuity tester are required to test the switch.
1. Connect the continuity tester across the blade
terminal and the metal case of the switch. With
0 psi pressure applied to the switch, the tester
should indicate continuity (switch closed).
2. Gradually increase the pressure to the switch. As
pressure increases through the range of
3.0/5.0 psi, the tester should indicate a change to
no continuity (switch open). The switch should
remain open as the pressure is increased to
90 psi maximum.
3. Gradually decrease the pressure through the
range of 3.0/5.0 psi. The tester should indicate a
change to continuity (switch closed) down to
0 psi.
4. Replace the switch if it does not operate as
specified.
Section 7
Retractable Starter
Section 7
Retractable Starter
WARNING: Spring Under Tension!
Retractable starters contain a powerful, recoil spring that is under tension. Always wear safety goggles when servicing retractable
starters and carefully follow instructions in this section for relieving spring tension.
Hex
Flange
Screws
Starter Housing
Handle with
Rope Retainer
2. Pull the starter handle out until the pawls
engage in the drive cup. Hold the handle in this
position and tighten the screws securely.
Rope Replacement
The rope can be replaced without complete starter
disassembly.
Spring and
Keeper
Rope
Pulley
Pawl Springs
Brake Washer
1. Remove the starter from the blower housing.
7
2. Pull the rope out approximately 12 in. and tie a
temporary (slip) knot in it to keep it from
retracting into the starter. See Figure 7-2.
Pawls
Slipknot
Brake Spring
Pawl Retainer
Handle
Plain Washer
Knot
Center Screw
Drive Cup
Rope Retainer
Figure 7-1. Retractable Starter – Exploded View.
Figure 7-2. Removing Starter Handle.
To Remove Starter
1. Remove the five hex flange screws securing the
starter to the blower housing.
2. Remove the starter.
To Install Starter
1. Install the retractable starter onto the blower
housing leaving the five hex flange screws
slightly loose.
3. Remove the rope retainer from inside the starter
handle. Untie the single knot and remove the
rope retainer and handle.
4. Hold the pulley firmly and untie the slipknot.
Allow the pulley to rotate slowly as the spring
tension is released.
5. When all spring tension on the starter pulley is
released, remove the rope from the pulley.
7.1
Section 7
Retractable Starter
6. Tie a single knot in one end of the new rope.
Pawls (Dogs) Replacement
7. Rotate the pulley counterclockwise (when
viewed from pawl side of pulley) until the spring
is tight (approximately 6 full turns of pulley).
To replace the pawls, follow disassembly steps 1-4
and reassembly steps 3-8 on the following pages. A
pawl repair kit is available which includes the
following components:
8. Rotate the pulley clockwise until the rope hole in
the pulley is aligned with the rope guide bushing
of the starter housing.
NOTE: Do not allow the pulley/spring to
unwind. Enlist the aid of a helper if
necessary, or use a C-clamp to hold the
pulley in position.
9. Insert the new rope through the rope hole in the
starter pulley and the rope guide bushing of the
housing. See Figure 7-3.
Keep Pulley
from Rotating
Rope Guide
Bushing
Rope Hole
in Pulley
Qty.
1
1
2
1
2
1
1
Description
Pawl Retainer
Center Screw
Pawl (Dog) Spring
Brake Spring
Starter Pawl (Dog)
Brake Washer
Washer
Disassembly
WARNING: Spring Under Tension!
Do not remove the center screw from starter until the spring
tension is released. Removing the center screw before releasing
spring tension, or improper starter disassembly, can cause the
sudden and potentially dangerous release of the spring. Follow
these instructions carefully to ensure personal safety and
proper starter disassembly. Make sure adequate face protection
is worn by all persons in the area.
1. Release spring tension and remove the handle
and starter rope. (Refer to “Rope Replacement,”
steps 2 through 5 on page 7.1).
2. Remove the center screw, washer, and pawl
retainer. See Figure 7-4.
Figure 7-3. Installing Rope.
10. Tie a slipknot approximately 12 in. from the free
end of the rope. Hold the pulley firmly and allow
it to rotate slowly until the slipknot reaches the
guide bushing of the housing.
11. Slip the handle and rope retainer onto the rope.
Tie a single knot at the end of the rope. Install the
rope retainer into the starter handle.
12. Untie the slipknot and pull on the handle until
the rope is fully extended. Slowly retract the rope
into the starter. When the spring is properly
tensioned, the rope will retract fully and the
handle will stop against the starter housing.
7.2
3. Remove the brake spring and brake washer. See
Figure 7-5.
4. Carefully note the positions of the pawls and
pawl springs before removing them.
Remove the pawls and pawl springs from the
starter pulley.
Section 7
Retractable Starter
Center Screw
and Washer
Pawl Retainer
Housing
Pulley
Figure 7-4. Center Screw, Washer and Pawl
Retainer.
Figure 7-6. Removing Pulley from Housing.
8. Note the position of the spring and keeper
assembly in the pulley. See Figure 7-7.
Brake Spring and
Brake Washer
Pawl Spring
Remove the spring and keeper assembly from the
pulley as a package.
WARNING: Spring Under Tension!
Do not remove the spring from the keeper. Severe personal
injury could result from the sudden uncoiling of the spring.
7
Pawls
Outer Spring Hook
Rope Hole
in Pulley
Figure 7-5. Brake Spring and Washer, Pawls, and
Pawl Springs.
5. Rotate the pulley clockwise 2 full turns. This will
ensure the spring is disengaged from the starter
housing.
6. Hold the pulley into the starter housing. Invert
the pulley/housing so the pulley is away from
your face and away from others in the area.
7. Rotate the pulley slightly from side to side and
carefully separate the pulley from the housing.
See Figure 7-6.
If the pulley and the housing do not separate
easily, the spring could be engaged in the starter
housing, or there is still tension on the spring.
Return the pulley to the housing and repeat step
5 before separating the pulley and housing.
Spring &
Keeper
Figure 7-7. Position of Spring and Keeper in
Pulley.
Inspection and Service
1. Carefully inspect the rope, pawls, housing, center
screw, and other components for wear or
damage.
2. Replace all worn or damaged components. Use
only genuine Kohler replacement parts as
specified in the Parts Manual. All components
shown in Figure 7-1 are available as service
parts. Do not use nonstandard parts.
7.3
Section 7
Retractable Starter
3. Do not attempt to rewind a spring that has come
out of the keeper. Order and install a new spring
and keeper assembly.
Pawl
4. Clean all old grease and dirt from the starter
components. Generously lubricate the spring
and center shaft with any commercially
available bearing grease.
Reassembly
1. Make sure the spring is well lubricated with
grease. Place the spring and keeper assembly into
the pulley (with spring toward pulley). See
Figure 7-7.
2. Install the pulley assembly into the starter
housing. See Figure 7-8. Make sure the pulley is
fully seated against the starter housing. Do not
wind the pulley and recoil spring at this time.
Pulley & Spring
Housing
Figure 7-8. Installing Pulley and Spring into
Housing.
3. Install the pawl springs and pawls into the
starter pulley. See Figure 7-9.
7.4
Pawl Spring
Figure 7-9. Installing Pawls and Pawl Springs.
4. Place the brake washer in the recess in the
starter pulley; over the center shaft.
5. Lubricate the brake spring sparingly with
grease. Place the spring on the washer. Make sure
the threads in the center shaft remain clean, dry,
and free of grease and oil.
6. Apply a small amount of Loctite® No. 271 to the
threads of the center screw. Install the center
screw, with washer and retainer, to the center
shaft. Torque the screw to 7.4-8.5 N·m
(65-75 in. lb.).
7. Tension the spring and install the rope and
handle as instructed in steps 6 through 12 under
“Rope Replacement” on page 7.2.
8. Install the starter to the engine blower housing
as instructed in ‘‘To Install Starter’’ on page 7.1.
Section 8
Electrical System and Components
Section 8
Electrical System and Components
This section covers the operation, service, and repair of
the electrical system components. Systems and
components covered in this section are:
• Spark Plugs
• Battery and Charging System
• Electronic CD Ignition System (including SMARTSPARK™ on applicable models)
• Electric Starter
NOTE: Do not clean spark plugs in a machine
using abrasive grit. Some grit could
remain in the spark plug and enter the
engine, causing extensive wear and
damage.
3. Check the gap using a wire feeler gauge. Adjust
the gap to 0.76 mm (0.030 in.) by carefully
bending the ground electrode. See Figure 8-1.
Spark Plugs
Engine misfire or starting problems are often caused by
a spark plug that has improper gap or is in poor
condition.
Wire Gauge
Spark Plug
The engine is equipped with the following spark plugs:
The standard spark plug is a Champion®
RC12YC (Kohler Part No. 12 132 02-S). RFI
compliant engines use a Champion® XC12 YC
(Kohler 25 132 14-S) spark plug. A highperformance spark plug, Champion® Platinum
3071 (used on Pro Series engines, Kohler Part
No. 25 132 12-S) is also available. Equivalent
alternate brand plugs can also be used.
Gap:
0.76 mm (0.030 in.)
Thread Size: 14 mm
Reach:
19.1 mm (3/4 in.)
Hex Size:
15.9 mm (5/8 in.)
8
Type:
Spark Plug Service
Remove the spark plugs after every 200 hours of
operation. Check their condition and either reset the
gap or replace with new plugs as necessary. To service
the plugs, perform the following steps:
1. Before removing a spark plug, clean the area
around the base of the plug to keep dirt and debris
out of the engine.
2. Remove the plug and check its condition. See
“Inspection” following this procedure. Replace the
plug if necessary.
Ground
Electrode
0.76 mm (0.030 in.) Gap
Figure 8-1. Servicing Spark Plug.
4. Reinstall the spark plug into the cylinder head
and torque to 24.4-29.8 N·m (18-22 ft. lb.).
Inspection
Inspect each spark plug as it is removed from the
cylinder head. The deposits on the tip are an
indication of the general condition of the piston rings,
valves, and carburetor.
Normal and fouled plugs are shown in the following
photos:
8.1
Section 8
Electrical System and Components
Normal: A plug taken from an engine operating under
normal conditions will have light tan or gray colored
deposits. If the center electrode is not worn, a plug in
this condition could be set to the proper gap and
reused.
Carbon Fouled: Soft, sooty, black deposits indicate
incomplete combustion caused by a restricted air
cleaner, over-rich fuel mixture, weak ignition, or poor
compression.
Worn: On a worn plug, the center electrode will be
rounded and the gap will be greater than the specified
gap. Replace a worn spark plug immediately.
8.2
Wet Fouled: A wet plug is caused by excess fuel or oil
in the combustion chamber. Excess fuel could be
caused by a restricted air cleaner, a carburetor
problem, or operating the engine with too much
choke. Oil in the combustion chamber is usually
caused by a restricted air cleaner, a breather problem,
or worn piston rings, cylinder walls or valve guides.
Overheated: Chalky, white deposits indicate very high
combustion temperatures. This condition is usually
accompanied by excessive gap erosion. Lean
carburetor settings, an intake air leak, or incorrect
spark timing are normal causes for high combustion
temperatures.
Section 8
Electrical System and Components
Battery
General
A 12-volt battery with 400 cold cranking amps is
generally recommended for starting in all conditions.
A smaller capacity battery is often sufficient if an
application is started only in warmer temperatures.
Refer to the following table for minimum cold
cranking amp (cca) capacities, based on anticipated
ambient temperatures. The actual cold cranking
requirement depends on engine size, application, and
starting temperatures. The cranking requirements
increase as temperatures decrease and battery
capacity shrinks. Refer also to the operating
instructions for the piece of equipment for specific
battery requirements.
2. Keep the cables, terminals, and external surfaces
of the battery clean. A build-up of corrosive acid
or grime on the external surfaces can cause the
battery to self-discharge. Self-discharge occurs
rapidly when moisture is present.
3. Wash the cables, terminals, and external surfaces
with a mild baking soda and water solution.
Rinse thoroughly with clear water.
NOTE: Do not allow the baking soda solution to
enter the cells, as this will destroy the
electrolyte.
Battery Test
To test the battery, you will need a DC voltmeter.
Perform the following steps (see Figure 8-2):
Battery Size Recommendations
Temperature
Battery Required
Above 32°F (0°C)
200 cca minimum
0°F to 32°F (-18°C to 0°C)
250 cca minimum
-5°F to 0°F (-21°C to -18°C)
300 cca minimum
-10°F (-23°C) or below
400 cca minimum
1. Connect the voltmeter across the battery
terminals.
2. Crank the engine. If the battery drops below 9
volts while cranking, the battery is too small,
discharged, or faulty.
If the battery charge is not sufficient to turn over the
engine, recharge the battery.
DC Voltmeter
8
Battery Maintenance
Regular maintenance is necessary to prolong battery
life.
WARNING: Explosive Gas!
Batteries produce explosive hydrogen gas while being
charged. To prevent a fire or explosion, charge batteries only
in well ventilated areas. Keep sources of ignition away from
the battery at all times. Keep batteries out of the reach of
children. Remove all jewelry when servicing batteries.
Before disconnecting the negative (-) ground cable, make
sure all switches are OFF. If ON, a spark will occur at the
ground cable terminal, which could cause an explosion if
hydrogen gas or gasoline vapors are present.
Battery
Figure 8-2. Battery Voltage Test.
1. Regularly check the level of electrolyte. Add
distilled water as necessary to maintain the
recommended level.
NOTE: Do not overfill the battery. Poor
performance or early failure due to loss
of electrolyte will result.
8.3
Section 8
Electrical System and Components
Electronic CD Ignition Systems
Red
Ignition
Module
Input
Red
Starter and
Carburetor
Solenoid
Input
Red
Green
Carburetor
Solenoid
Oil
Pressure
Safety
Spark
Advance
Module
(Optional)
White
Red
Oil Pressure
B+ and
Spark
Safety Input
Carburetor
Plugs
Solenoid
Input
B+
Violet
RectifierRegulator
Ignition
Modules
White
Figure 8-3. Electronic CD Ignition System (For Customer Connected Tractor Applications).
The SMART-SPARK™ ignition system used on some
models is an advanced version of the CD ignition
system used on other CV engines. Its operation can be
best understood by first understanding the standard
system and how it works. Since both systems will
continue in use, it is advantageous to understand them
both. The operation of the standard system is
explained first then expanded to cover SMARTSPARK™.
8.4
Operation of CD Ignition Systems
A. Capacitive Discharge with Fixed Timing
This system (Figure 8-3) consists of the following
components:
•
A magnet assembly which is permanently affixed
to the flywheel.
•
Two electronic capacitive-discharge ignition
modules which mount on the engine crankcase
(Figure 8-4).
•
A kill switch (or key switch) which grounds the
modules to stop the engine.
•
Two spark plugs.
Section 8
Electrical System and Components
Kill Switch or
‘‘Off’’ Position of
Key Switch
Ignition
Modules
Spark Plug
Magnet
0.28/0.33 mm
(0.011/0.013 in.)
Air Gap
Flywheel
Figure 8-4. Capacitive Discharge (Fixed Timing) Ignition System.
The timing of the spark is controlled by the location of the flywheel magnet group as referenced to engine top
dead center.
D1
8
C1
T1
SCS
Spark
Plug
L1
L2
P
S
Figure 8-5. Capacitive Discharge Ignition Module Schematic.
Operation: As the flywheel rotates, the magnet
grouping passes the input coil (L1). The
corresponding magnetic field induces energy into the
input coil (L1). The resultant pulse is rectified by D1
and charges capacitor C1. As the magnet assembly
completes its pass, it activates the triggering device
(L2), which causes the semiconductor switch (SCS) to
turn on. With the device switch “ON,” the charging
capacitor (C1) is directly connected across the primary
(P) of the output transformer (T1). As the capacitor
discharges, the current initiates a fast rising flux field
in the transformer core. A high voltage pulse is
generated from this action into the secondary winding
of the transformer. This pulse is delivered to the spark
plug gap. Ionization of the gap occurs, resulting in an
arc at the plug electrodes. This spark ignites the fuelair mixture in the combustion chamber.
8.5
Section 8
Electrical System and Components
B. Capacitive Discharge with Electronic Spark
Advance (SMART-SPARK™)
SMART-SPARK™ equipped engines utilize an
electronic capacitive discharge ignition system with
electronic spark advance. A typical application (Figure
8-6) consists of the following components:
A magnet assembly which is permanently affixed
to the flywheel.
•
Two electronic capacitive discharge ignition
modules which mount on the engine crankcase
(Figure 8-6).
•
A spark advance module which mounts to the
engine shrouding (Figure 8-7).
Figure 8-6. Capacitive Discharge Ignition System
with Spark Advance.
•
A 12 volt battery which supplies current to the
spark advance module.
•
A kill switch (or key switch) which grounds the
spark advance module to stop the engine.
The timing of the spark is controlled by the location of
the flywheel magnet group as referenced to engine top
dead center and the delay created by the spark
advance module.
•
Two spark plugs.
Green
or Black
•
V+ (7.2V)
From Brown Conditioning
Input
Circuit
Coil
B+ (12 VDC)
Red
Delay
Circuit
Comparator
Charge
Pump
Reset
Circuit
Figure 8-7. Block Diagram - Spark Advance Module.
8.6
Power
Source
Pulse
Generator
Yellow
To
Semi-Conductor
Switch
Section 8
Electrical System and Components
Operation: The ignition module for this system
operates in the same fashion as the fixed timing
module, except the trigger circuit for the
semiconductor (L2, Figure 8-5) is replaced by the
spark advance module (Figure 8-7).
The pulse generated by the input coil of the ignition
module (L1, Figure 8-5) is fed to the input of the
conditioning circuit. The conditioning circuit shapes
this pulse, putting it in a useable form for the
additional circuits. This pulse starts the charge pump,
which charges a capacitor in a linear fashion that can
be directly related to the engine speed. At the same
time the pulse resets the delay circuit for length of the
pulse width. The comparator is off during this period
and no output is generated. As soon as the original
pulse drops back to zero, the capacitor in the delay
circuit begins to charge.
When the charge on the delay capacitor exceeds the
charge on the charge pump capacitor the comparator
changes state, activating the pulse generator. This
pulse turns “ON” the CD ignition module
semiconductor. Energy is then transferred to the
secondary of the output transformer (T1, Figure 8-5).
The high voltage pulse generated here is delivered to
the spark plug, causing arcing of the spark gap and
igniting the fuel-air mixture in the combustion
chamber. As the trigger pulse is generated, all
associated circuits are reset, their capacitors
discharged. The longer it takes the delay circuit to
surpass the charge pump capacitor voltage, the later
the trigger pulse will occur, retarding the timing
accordingly.
Troubleshooting CD Ignition Systems
The CD ignition systems are designed to be trouble
free for the life of the engine. Other than periodically
checking/replacing the spark plugs, no maintenance or
timing adjustments are necessary or possible.
Mechanical systems do occasionally fail or break
down however, so the following troubleshooting
information is provided to help you get to the root of
a reported problem.
CAUTION: High-Energy Electric Spark!
The CD ignition systems produce a high-energy electric
spark, but the spark must be discharged, or damage to the
system can result. Do not crank or run an engine with a
spark plug lead disconnected. Always provide a path for the
spark to discharge to ground.
Reported ignition problems are most often due to
poor connections. Before beginning the test procedure,
check all external wiring. Be certain all ignitionrelated wires are connected, including the spark plug
leads. Be certain all terminal connections fit snugly.
Make sure the ignition switch is in the run position.
NOTE: The CD ignition systems are sensitive to
excessive load on the kill lead. If a customer
complains of hard starting, low power, or
misfire under load, it may be due to excessive
draw on the kill circuit. Perform the
appropriate test procedure.
Test Procedure for Standard (Fixed Timing) CD
Ignition System
Isolate and verify the trouble is within the engine
ignition system.
1. Locate the plug connectors where the wiring
harnesses from the engine and equipment are
joined. Separate the connectors and remove the
white “kill” lead from the engine connector.
Rejoin the connectors and position or insulate the
kill lead terminal so it cannot touch ground. Try
to start** the engine to verify whether the
reported problem is still present.
a. If the problem is gone, the electrical
system on the unit is suspect. Check the key
switch, wires, connections, safety interlocks,
etc.
b. If the problem persists the condition is
associated with the ignition or electrical
system of the engine. Leave the kill lead
isolated until all testing is completed.
**NOTE: If the engine starts or runs during any of the
testing, you may need to ground the kill lead
to shut it down. Because you have
interrupted the kill circuit, it may not stop
using the switch.
2. Test for spark on both cylinders with Kohler
ignition tester (see Section 2). Disconnect one
spark plug lead and connect it to the post
terminal of the tester. Connect the clip to a good
ground, not to the spark plug. Crank the engine
and observe the tester spark gap. Repeat the
procedure on the other cylinder. Remember to
reconnect the first spark plug lead.
8.7
8
Section 8
Electrical System and Components
a. If one side is not firing, check all wiring,
connections, and terminations on that side. If
wiring is okay, replace ignition module and
retest for spark.
b. If the tester shows spark, but the engine
misses or won’t run on that cylinder, try a new
spark plug.
c. If neither side is firing, recheck position of
ignition switch and check for shorted kill lead.
Test Procedure for SMART-SPARKTM Ignition
Systems
The following procedures are provided for
troubleshooting ignition problems on SMARTSPARKTM equipped engines. They will allow you to
isolate and pinpoint the failed component(s).
Special Tools Required:
• Hand Tachometer
• Tester* (see Section 2)
• Automotive timing light
• Multi-meter (digital)
Specifications Required:
• Spark plug gap 0.76 mm (0.030 in.)
• Ignition module air gap 0.28/0.33 mm
(0.011-0.013 in.), 0.30 mm (0.012 in.) nominal
*NOTE: Ignition tester (see Section 2) must be used to
test ignition on these engines. Use of any
other tester can result in inaccurate findings.
Battery on unit must be fully charged and
properly connected before making any of
these tests (a battery that is hooked up or
charged backward will crank the engine, but
it won’t have spark). Be sure drive is in
neutral and all external loads are
disconnected.
Test 1. Isolate and verify the trouble is within the
engine ignition system.
1. Locate the plug connectors where the wiring
harnesses from the engine and equipment are
joined. Separate the connectors and remove the
white “kill” lead from the engine connector.
Rejoin the connectors and position or insulate the
kill lead terminal so it cannot touch ground. Try
to start** the engine to verify whether the
reported problem is still present.
8.8
a. If the problem is gone, the electrical system on
the unit is suspect. Check the key switch,
wires, connections, safety interlocks, etc.
b. If the problem persists the condition is
associated with the ignition or electrical
system of the engine. Leave the kill lead
isolated until all testing is completed.
**NOTE: If the engine starts or runs during any of the
testing, you may need to ground the kill lead
to shut it down. Because you have
interrupted the kill circuit, it may not stop
using the switch.
Test 2. Test for spark.
1. With the engine stopped, disconnect one spark
plug lead. Connect the spark plug lead to post
terminal of spark tester (see Section 2) and attach
tester clip to a good engine ground.
NOTE: If two testers are available, testing can be
performed simultaneously for both cylinders.
However, if only one tester is available, two
individual tests must be performed. The side
not being tested must have the spark plug
lead connected or grounded. Do not crank
the engine or perform tests with one spark
plug lead disconnected and not grounded or
permanent system damage may occur.
2. Crank the engine over, establishing a minimum of
550-600 RPM, and observe tester(s) for spark.
3. On a twin cylinder engine, repeat the spark test
on the opposite cylinder if cylinders are being
tested individually.
a. If both cylinders have good spark, but the
engine runs poorly, install new spark plugs
gapped at 0.76 mm (0.030 in.), and retest
engine performance. If problem persists, go
to Test 3.
b. If one cylinder had good spark, but the
other cylinder had no spark or intermittent
spark, go to Test 3.
c. If there was no spark or intermittent spark
on both cylinders, go to Test 4.
Section 8
Electrical System and Components
Test 3. Check for timing advance.
Test 4. Test the ignition modules and connections.
1. Remove the blower housing from the engine.
Inspect the wiring for any damage, cuts, bad
crimps, loose terminals or broken wires.
2. Disconnect the leads from the ignition module(s)
and clean all of the terminals (male and female)
with aerosol electrical contact cleaner to remove
any old dielectric compound, dark residue, dirt,
or contamination. Disconnect the spark plug
leads from the spark plugs.
Figure 8-8.
1. Make a line near the edge of the flywheel screen
with a marking pen or narrow tape.
2. Connect an automotive timing light to cylinder
that had good spark.
Figure 8-9.
3. Run the engine at idle and use the timing light
beam to locate the line on the screen. Draw a line
on the blower housing adjacent to the line on the
screen. Accelerate to full throttle and watch for
movement of the line on the screen relative to the
line on the blower housing. If both cylinders had
good spark, repeat the test on the other cylinder.
3. Remove one of the mounting screws from each of
the ignition modules. If the mounting screws are
black, remove them both and discard. Replace
them with part number M-561025-S. Look in the
mounting hole with a flashlight and use a small
round wire brush to remove any loose rust from
the laminations inside the mounting hole.
4. Refer to the chart on page 8.10 to identify which
ignition module(s) you have. If they are the
smaller style, check the vendor part number on
the face. All modules with vendor part numbers
MA-2, MA-2A, or MA-2B (Kohler Part No.
24 584 03) should be replaced with 24 584 11 or
24 584 15-S. For small modules with vendor
numbers MA-2C or MA-2D (Kohler Part No.
24 584 11), or the larger style modules
(24 584 15-S and 24 584 36-S), use a digital
ohmmeter to check the resistance values and
compare them to the table following. When
testing resistance to the laminations, touch the
probe to the laminations inside the screw hole, as
some laminations have a rust preventative
coating on the surface which could alter the
resistance reading.
a. If all of the resistance values are within the
ranges specified in the table, go to step 5.
b. If any of the resistance values are not within
the ranges specified in the table,# that
module is faulty and must be replaced.
#
a. If the line on the screen moved away from
the line on the blower housing during
acceleration, the SAM is working properly. If
it didn’t move away, go to Test 5.
NOTE: The resistance values apply only to
modules that have been on a running
engine. New service modules may have
higher resistance until they have been
run.
b. If you were able to check timing on both
cylinders, the lines you made on the blower
housing should be 90° apart. If they’re not,
go to Test 4.
8.9
8
Section 8
Electrical System and Components
Ignition Module Resistance Table
24 584 03 or
24 584 11
24 584 15-S or
24 584 36-S
(1 11/16 in. High)
(2 1/16 in. High)
2 1
4
2 1
5) Loosen the mounting screws, allow the
magnet to pull the module down
against the feeler gauge, and retighten
the mounting screws.
3
Test
24 584 03
24 584 15-S 24 584 36-S
(Use Digital
24 584 11
(2 1/16 in. H) (2 1/16 in. H)
Ohmmeter) (1 11/16 in. H)
From No.
1 to 4
945 to
1175 ohms
890 to
1175 ohms
590 to
616 ohms
From No.
2 to 4
149 to
166 ohms
119 to
136 ohms
183 to
208 ohms
From No.
3 to 4
3750 to
7000 ohms
5600 to
9000 ohms
8000 to
40,000 ohms
5. Check and/or adjust the ignition module air
gap(s). An air gap of 0.28/0.33 mm
(0.011/0.013 in.) must be maintained under all
three legs of the ignition module(s). Checking/
adjusting should be performed with the parts
at room temperature.
a. If the module was not loosened or
replaced, check that the specified air gap is
present under all three legs. If the gap is
correct, reinstall the second mounting
screw removed earlier and recheck gap
after tightening.
b. If the gap is incorrect, or the module was
loosened or replaced, adjust the gap as
follows:
1) Turn the flywheel magnet away from
the module position.
2) Attach the module to the mounting
legs, pull it away from the flywheel,
and snug the screws to hold it
temporarily.
3) Rotate the flywheel so the magnet is
centered under the module.
8.10
4) Position a 0.30 mm (0.012 in.) feeler
gauge between the magnet and all three
legs of the module. The ignition module
air gap is critical to proper system
performance. Do not attempt to set it
with a business card or folded
microfiche card, use the feeler gauge
specified.
6) Rotate the flywheel to remove the feeler
gauge, position the magnet back under
the module, and recheck that the
specified gap, minimum of 0.28 mm
(0.011 in.) exists under each leg of the
module. When you are certain the gap is
correct, torque the module mounting
screws to 4.0 N·m (35 in. lb.). On a
twin cylinder engine, repeat these 6
steps to set the opposite side ignition
module.
6. Reattach the lead wires to the ignition module(s),
noting if resistance is felt, indicating a snug fit
between the male and female terminals. If any
connections do not feel snug, disconnect the lead,
lightly pinch the female terminal with a pliers, and
recheck the fit.
7. When the integrity of all connections has been
verified, repeat the spark test (Test 2).
a. If a strong, steady spark is now present
(both sides on a twin), your problem should
be corrected. Go to step 4 of Test 5.
b. If there is still a spark problem, perform all
of Test 5.
Test 5. Test the SAM.
1. Trace the red power source lead from the SAM to
the harness connection. Separate the connector and
connect the red lead of a DC voltmeter to the
harness terminal. Trace the ground lead from the
SAM (black on singles, green on twins) to the
grounding screw. Connect the black voltmeter lead
to the eyelet terminal of the ground lead or the
ground screw/bolt. Check the voltage with the key
switch in both the “START” and “RUN” positions.
A minimum of 7.25 volts must be present.
Section 8
Electrical System and Components
a. If correct voltage is not measured, connect
black voltmeter lead directly to the negative
(-) post of the battery and test voltage again
in both key positions. If correct voltage is
now indicated, check the ground circuit
connections. If the ground screw/bolt or any
other fasteners in the ground circuit are black
(oxide-coated), replace them with zinc plated
(silver colored) fasteners.
b. If correct voltage is still not indicated, check
the harness connector terminal for a good
connection and crimp to the lead. Then trace
the power source circuit back through the
harness, key switch, etc., looking for any poor
connections, or faulty circuits.
To Test – Using 25 761 21-S Tester
ASAM (only) Test Procedure
NOTE: The SAM must be at room temperature when
tested. Disconnect all of the SAM leads,
isolating it from the main wiring harness and
the ignition module(s). Testing may be
performed with the module mounted or
loose. The figures show the part removed
from the engine for clarity.
2. Disconnect all of the SAM leads, isolating it from
the engine. Test the SAM according to style with
tester 25 761 21-S (tests ASAM style modules
only), or tester 25 761 40-S (tests both ASAM and
DSAM style modules). Use the test instructions
following, or those provided with the tester. If the
SAM tests bad, replace it.
3. Reattach the SAM leads, verifying a snug fit at the
ignition module terminals. If any connections do
not feel snug, disconnect the lead, lightly pinch the
female terminal with a pliers, and recheck the fit.
4. Seal the base of the ignition module connections
with GE/Novaguard G661 (see Section 2) or
Fel-Pro Lubri-Sel dielectric compound. The beads
should overlap between the two connections† to
form a solid bridge of compound. Do not put any
compound inside the connectors.
†
Figure 8-10.
1. Connect the tester to the SAM as follows:
8
Attach:
A.
B.
C.
D.
The yellow tester lead to the long yellow module lead.
The brown tester lead to the long brown module lead.
The red tester lead to the red module lead.
The green tester lead to the green module lead.
Caution: Do not allow the alligator clip leads to touch
each other.
The 24 584 15-S ignition modules have a
separator/barrier between the terminals. On
these modules, seal the base of the terminal
if any portion of it is exposed, but it is not
necessary to have overlapping beads of
sealant between the connections.
5. Test for spark (Test 2) to be sure the system is
working, before you reinstall the blower housing.
If there is still a spark problem on one side, replace
that ignition module and recheck spark.
Figure 8-11.
8.11
Section 8
Electrical System and Components
Figure 8-12.
2. Check the SAM part number stamped on the side
of the housing. Verify that you have an analog
SAM (ASAM) Part No. 24 584 10 or lower, not a
digital SAM (DSAM) Part No. 24 584 18 and
higher. Follow sub-step a for testing an ASAM
with this tester. Digital SAM (DSAM) modules
require Tester 25 761 40-S for proper testing.
a. Depress the tester button and hold it down.
After approximately four seconds, a
numerical sequence should be displayed,
beginning with 1 or 2 and continuing to 8 or 9,
followed by a letter “P” (pass) or “F” (fail).
See Figures 8-11 and 8-12. Do not release the
tester button until the test cycle completes and
the display goes off*. If you get a “-” sign
instead of the numerical sequence, and /or an
“F” at the end of the cycle, the SAM is
probably bad. Recheck all of the connections,
check the condition of the tester battery** and
repeat the test. If you get the “-” sign and/or
“F” again in the retest, replace that SAM.
*IMPORTANT!
Allow 15-20 seconds for the tester to clear and reset
itself between tests or if the test is interrupted before
completion of the test cycle. Otherwise, a false reading
may be displayed in the form of a “-” or a faint “8”.
3. Disconnect the yellow and brown tester leads
from the long module leads. Connect the brown
tester lead to the short brown module lead.
Connect the yellow tester lead to the short yellow
(or pink) module lead. See Figure 8-13. Leave the
red and green leads connected. Repeat step 2.
8.12
Figure 8-13.
** The tester is powered by a 9-volt battery. Most
SAMs are designed to operate down to a minimum
of 7.25 volts. If the tester battery drops below that
level, incorrect test readings will result. The tester
battery should be checked periodically by
connecting a DC voltmeter between the red and
green lead wires, with the tester connected to a
SAM. Press and hold the test button for a full test
cycle (‘‘F’’ or ‘‘P’’ appears and then display shuts
off), while monitoring the voltage reading on the
voltmeter. If the voltage drops below 7.5 at any time
during the cycle, the 9-volt tester battery must be
replaced. Use an extended life (alkaline) battery.
To replace the battery, remove the outer set of screws
on the faceplate and carefully lift the panel from the
body. Unplug the connector and pull battery (with
mounting tape) off the back of the tester. Attach the
connector to the new battery and mount the battery to
the case with double-backed tape. Reinstall the
faceplate and secure with the four screws.
Section 8
Electrical System and Components
b. If it is a DSAM (all except 24 584 09 or
24 584 10), connect the tester as follows:
To Test – Using 25 761 40-S Tester
DSAM/ASAM Test Procedure
• Yellow tester lead to the long yellow
module lead.
• Brown tester lead to the long brown
module lead.
• Red tester lead to the red module lead.
• Black tester lead to the green or black
module ground lead with the eyelet#
terminal.
• Pink tester lead to the short yellow or pink
module lead.
• Brown tester lead with black band or
terminal to the short brown module lead.
NOTE: The SAM must be at room temperature when
tested. Disconnect all of the SAM leads,
isolating it from the main wiring harness and
the ignition module(s). Testing may be
performed with the module mounted or
loose. The figures show the part removed
from the engine for clarity. See Figure 8-14.
ASAM Module
Test Connections
#
NOTE: Some modules contain two black ground
leads, with one containing a white stripe. Do
not connect to the black/white lead with the
bullet connector or a “Fail” test result will
occur, regardless of actual condition.
Caution: Do not allow alligator clip leads to touch
each other.
DSAM Module Test
Connections
Figure 8-14. Connected Tester Leads.
The test procedure for twin cylinder SAMs will vary
slightly, depending on whether the module is analog
(ASAM) or digital (DSAM).
1. Check the SAM part number stamped on the end
of the housing.
a. If it is an ASAM (24 584 09 or 24 584 10),
separate the short yellow and brown leads
from the long ones. Each set will be tested
separately. Connect the tester to the SAM as
follows:
• Yellow tester lead to long yellow module
lead.
• Brown tester lead to long brown module
lead.
• Red tester lead to the red module lead.
• Black tester lead to the black or green
module lead.
The remaining tester leads (pink and brown
with black band) are not used for testing
ASAMs.
2. Recheck the SAM part number, noting the last
two digits. Refer to the table below or on the
tester faceplate to determine the test number to
be used.
SAM 12 584 12 24 584 30 24 584 33
24 584 32
24 584 09
Part No. 24 584 10 24 584 31 24 584 34
Test No.
1
SAM
Part No.
-
Test No.
5
2
3
4
24 584 18 24 584 19 24 584 38
24 584 27
24 584 39
6
7
8
3. Depress the tester button repeatedly until the
correct test number appears on the display. After
a few seconds, the test number will flash three
times and the test will begin. A reverse numerical
sequence will be displayed, starting with a 6 and
progressing down to 1, followed by a “P” (pass)
or “F” (fail), indicating the condition of the part.*
See Figures 8-15 and 8-16. If testing an ASAM,
return to step 1 and move the yellow and brown
tester leads to the short set of module leads, then
repeat the test.
8.13
8
Section 8
Electrical System and Components
4. If you get a “-“ sign instead of the numerical
sequence, and/or an “F” at the end of the test
cycle, recheck all of the connections, check the
condition of the tester battery** and repeat the
test. If you get the “-“or “F” sign again in the
retest replace the SAM.
*IMPORTANT!
Allow 15-20 seconds for the tester to clear and reset
itself between tests or if the test is interrupted before
completion of the test cycle. Otherwise, a false reading
may be displayed in the form of a “-” or a faint “8”.
** The tester is powered by a 9-volt battery. Most
SAMs are designed to operate down to a minimum
of 7.25 volts. If the tester battery drops below that
level, incorrect test readings will result. The tester
battery should be checked periodically by
connecting a DC voltmeter between the red and
green lead wires, with the tester connected to a
SAM. Press and hold the test button for a full test
cycle (‘‘F’’ or ‘‘P’’ appears and then display shuts
off), while monitoring the voltage reading on the
voltmeter. If the voltage drops below 7.5 at any time
during the cycle, the 9-volt tester battery must be
replaced. Use an extended life (alkaline) battery.
To replace the battery, remove the outer set of screws
on the faceplate and carefully lift the panel from the
body. Unplug the connector and pull battery (with
mounting tape) off the back of the tester. Attach the
connector to the new battery and mount the battery to
the case with double-backed tape. Reinstall the
faceplate and secure with the four screws.
Battery Charging System
Figure 8-15. Select Test Number.
General
Most engines are equipped with a 15 or 20 amp
regulated charging system. Some have a 25 amp
regulated charging system. See Figure 8-17 and 8-18
for the 15/20/25 amp charging system diagram. Some
engines utilize a 3 amp unregulated system with
optional 70 watt lighting circuit. Refer to Figure 8-23.
NOTE: Observe the following guidelines to avoid
damage to the electrical system and
components:
•
Make sure the battery polarity is correct. A
negative (-) ground system is used.
•
Disconnect the rectifier-regulator plug and/or the
wiring harness plug before doing any electric
welding on the equipment powered by the
engine. Also, disconnect all other electrical
accessories in common ground with the engine.
•
Prevent the stator (AC) leads from touching or
shorting while the engine is running. This could
damage the stator.
Figure 8-16. “Pass” Indicator.
8.14
Section 8
Electrical System and Components
15/20/25 Amp Regulated Charging System
8
Figure 8-17. Wiring Diagram - 15/20/25 Amp Regulated Battery Charging System with Fixed Timing.
8.15
Section 8
Electrical System and Components
Figure 8-18. Wiring Diagram - 15/20/25 Amp Regulated Battery Charging System with Variable Ignition
Timing SMART-SPARK™.
Figure 8-19. 15 Amp Stator and Rectifier-Regulator.
8.16
Figure 8-20. 20 Amp Stator and Rectifier-Regulator.
Section 8
Electrical System and Components
1st Style
25 Amp Stator
2nd Style
Figure 8-21. 25 Amp Stator and Rectifier-Regulators.
3 Amp Unregulated Charging System
Ground-To-Kill Lead (White)
A
Light
8
R
Ignition
Modules
(Blue)
S
B (Red)
GND
Spark
Plug
Spark
Plug
Keyswitch
(Black)
Optional
Fuse
Optional
Oil SentryTM
Switch
(Indicator Light)
Diode
(Yellow)
Optional
Ammeter
3 Amp/70 Watt
Flywheel Stator
Lights
Optional
Oil SentryTM
Switch
(Shutdown)
12 V. Battery
Solenoid
Starter
Figure 8-22. Wiring Diagram - 3 Amp Unregulated Battery Charging System/70 Watt Lighting.
8.17
Section 8
Electrical System and Components
3 Amp Charging Stator
Lighting Lead
(Yellow)
Diode
Charging Lead
(Black)
Lighting Stator
Figure 8-23. 3 Amp/70 Watt Stator.
Stator
The stator is mounted on the crankcase behind the
flywheel. Follow the procedures in Section 9 “Disassembly” and Section 11 - “Reassembly” if stator
replacement is necessary.
Rectifier-Regulator
The rectifier-regulator is mounted on the blower
housing. See Figure 8-24. To replace it, disconnect the
plug(s), remove the two mounting screws, and ground
wire or metal grounding strap.
NOTE: When installing the rectifier-regulator, take
note of the terminal markings and install the
plug(s) accordingly.
RectifierRegulator
To Test –
NOTE: Disconnect all electrical connections attached
to the rectifier-regulator. Testing may be
performed with the rectifier-regulator
mounted or loose. The figures show the part
removed from the engine for clarity. Repeat
the applicable test procedure two or three
times to determine the condition of the part.
15 Amp Rectifier-Regulators
1. Connect the tester ground lead (with spring
clamp) to the body of the rectifier-regulator being
tested.
2. Connect the tester red lead to the B+ terminal of
the rectifier-regulator and the two black tester
leads to the two AC terminals. See Figure 8-25.
Ground
Strap
(or lead)
Figure 8-24. Rectifier-Regulator.
Testing of the rectifier-regulator may be performed as
follows, using the appropriate Rectifier-Regulator
Tester, (see Section 2).
8.18
Figure 8-25.
Section 8
Electrical System and Components
3. Plug the tester into the proper AC outlet/power
supply for tester being used. Turn on the power
switch. See Figure 8-26. The ‘‘POWER’’ light
should be illuminated and one of the four status
lights may be on as well. This does not represent
the condition of the part.
20/25 Amp Rectifier-Regulators
1. Connect the single lead adapter in between the B+
(center) terminal of the rectifier-regulator being
tested and the squared single end of the tandem
adapter lead. See Figure 8-28.
Figure 8-28.
Figure 8-26.
4. Press the ‘‘TEST’’ button until a “click” is heard
and then release. See Figure 8-27. Momentarily
one of the four status lights will illuminate,
indicating the condition of the part.
2. Connect the tester ground lead (with spring
clamp) to the body of the rectifier-regulator.
3. Connect the red lead and one of the black leads to
the pair of terminals on the open end of the
tandem adapter lead (connections are not location
specific).
4. Connect the remaining black lead from the tester
to one of the outer AC terminals on the rectifierregulator. See Figure 8-29.
Figure 8-27.
a. If the “OK” (green) light comes on and stays
steady, the part is good and may be used.
b. If any other light is displayed,* the rectifierregulator is faulty and should not be used.
*NOTE: A flashing “LOW” light can also occur as a
result of an inadequate ground lead
connection. Make certain connection location
is clean and clamp is secure.
Figure 8-29.
5. Plug the tester into the proper AC outlet/power
supply for tester being used. Turn on the power
switch. The ‘‘POWER’’ light should be
illuminated and one of the four status lights may
be on as well. See Figure 8-26. This does not
represent the condition of the part.
8.19
8
Section 8
Electrical System and Components
6. Press the ‘‘TEST’’ button until a ‘‘click’’ is heard
and then release. See Figure 8-27. Momentarily
one of the four status lights will illuminate
indicating the partial condition of the part.
a. If the ‘‘OK’’ (green) light comes on, disconnect
the tester black lead attached to one AC
terminal and reconnect it to the other AC
terminal. Repeat the test. If the ‘‘OK’’ (green)
light comes on again, the part is good and
may be used.
b. If any other light is displayed* in either of the
tests, the rectifier-regulator is faulty and
should not be used.
*NOTE: A flashing ‘‘LOW’’ light can also occur as a
result of an inadequate ground lead
connection. Make certain the connection
location is clean and the clamp is secure.
25 Amp Rectifier-Regulators (Original Style)
1. Connect the squared single end of the tandem
lead adapter to the B+ (center/red) lead of the
rectifier-regulator being tested. See Figure 8-30.
Figure 8-31.
5. Plug the tester into the proper AC outlet/power
supply for tester being used. Turn on the power
switch. The ‘‘POWER’’ light should be
illuminated and one of the four status lights may
be on as well. See Figure 8-26. This does not
represent the condition of the part.
6. Press the ‘‘TEST’’ button until a “click” is heard
and then release. See Figure 8-27. Momentarily
one of the four lights will relight indicating the
partial condition of the part.
a. If the “OK” (green) light comes on, disconnect
the tester black lead attached to the AC lead,
reconnect it to the opposite side AC lead, and
repeat the test. If the “OK” light (green) again
comes on, the part is good and may be used.
b. If any other light is displayed* in either of the
tests, the rectifier-regulator is faulty and
should not be used.
Figure 8-30.
2. Connect the ground lead of tester (with spring
clamp), to the housing of rectifier-regulator.
3. Connect the red lead and one of the black leads
from the tester to the pair of terminals on opposite
end of adapter lead (connections are not location
specific.).
4. Connect the remaining black lead from tester to one
of the black AC (outside) leads from rectifierregulator. See Figure 8-31.
8.20
*NOTE: A flashing “LOW” light can also occur as a
result of an inadequate ground lead
connection. Make certain connection location
is clean and clamp is secure.
4 Amp Unregulated Rectifiers
1. Connect the tester ground lead (with spring
clamp), to the body of the rectifier being tested.
2. Connect the red tester lead to the B+ (center)
terminal of the rectifier and the two black tester
leads to the two AC (outside) terminals. See
Figure 8-32.
Section 8
Electrical System and Components
4. Press the ‘‘TEST’’ button until a “click” is heard
and then release. See Figure 8-27. Momentarily
either the ‘‘HIGH’’, ‘‘LOW’’, or ‘‘SHORT’’ light
will flash.
a. If the “HIGH” light flashes on/off, the part is
good and may be used.
b. If any other light is displayed* the rectifier is
faulty and should not be used.
*NOTE: A flashing “LOW” light can also occur as a
result of an inadequate ground lead
connection. Make certain connection location
is clean and clamp is secure.
Figure 8-32.
3. Plug the tester into the proper AC outlet/power
supply for tester being used. Turn on the power
switch. The ‘‘POWER’’ light should be
illuminated and one of the four status lights may
be on as well. See Figure 8-26. This does not
represent the condition of the part.
Rectifier-Regulator
DC Voltmeter
8
(+)
(-)
Flywheel
Stator
Ammeter
Battery
Figure 8-33. Connections for Testing Charging System.
8.21
Section 8
Electrical System and Components
Troubleshooting Guide
15/20/25 Amp Battery Charging Systems
When problems occur in keeping the battery charged or the battery charges at too high a rate, the problem can
usually be found somewhere in the charging system or with the battery.
NOTE: Always zero ohmmeter on each scale before testing to ensure accurate readings. Voltage tests should
be made with the engine running at 3600 RPM - no load. The battery must be good and fully charged.
Problem
Test
1. Trace B+ lead from rectifierregulator to key switch, or other
accessible connection. Disconnect it
from switch or connection. Connect
an ammeter from loose end of B+
lead to positive terminal of battery.
Connect DC voltmeter from loose
end of B+ lead to negative terminal
of battery. With engine running at
3600 RPM, read voltage on
voltmeter.
If voltage is 13.8 volts or more,
place a minimum load of 5 amps*
on battery to reduce voltage.
Observe ammeter.
No Charge
to Battery
*NOTE: Turn on lights, if 60 watts
or more. Or place a 2.5
2. Remove connector from rectifierregulator. With engine running at
3600 RPM, measure AC voltage
across stator leads using an AC
voltmeter.
Conclusion
1. If voltage is 13.8-14.7 and charge rate increases when
load is applied, the charging system is OK and battery
was fully charged.
If voltage is less than 13.8 or charge rate does not
increase when load is applied, test stator (Tests 2 and 3).
If the voltage is low and does not increase, and there is
no charging/amperage output, disconnect and reconnect
the rectifier-regulator plug and retest.
a. If the ammeter shows charge for a short time but
then drops back to zero, the rectifier-regulator is
functioning correctly but the battery is faulty. Replace
the battery.
b. If no amperage/charge rate appears during the
retest, go to step 2.
2. If voltage is 28 volts or more, stator is OK. Rectifierregulator is faulty. Replace the rectifier-regulator.
If voltage is less than 28 volts, stator is probably faulty
and should be replaced. Test stator further using an
ohmmeter (Test 3).
3a. With engine stopped, measure the
resistance across stator leads using
an ohmmeter.
3a. If resistance is 0.064/0.2 ohms, the stator is OK.
3b. With the engine stopped, measure
the resistance from each stator lead
to ground using an ohmmeter.
3b. If the resistance is infinity ohms (no continuity), the
stator is OK (not shorted to ground).
If the resistance is infinity ohms, stator is open. Replace
stator.
If resistance (or continuity) is measured, the stator leads
are shorted to ground. Replace stator.
1. Perform same test as step 1 above.
Battery
Continuously
Charges at
High Rate
8.22
1. If the voltage is 14.7 volts or less the charging system is
OK. The battery is unable to hold a charge. Service
battery or replace as necessary.
If voltage is more than 14.7 volts, the rectifier-regulator is
faulty. Replace rectifier-regulator.
Section 8
Electrical System and Components
Troubleshooting Guide
3 Amp Battery Charging System with 70 Watt Lighting Stator
NOTE: Zero ohmmeters on each scale to ensure accurate readings. Voltage tests should be made with engine
running at 3000 RPM - no load. Battery must be good and fully charged.
Problem
Test
1. With engine running at 3000 RPM, measure
voltage across battery terminals using a DC
voltmeter.
Conclusion
1. If voltage is more than 12.5 volts, charging
system is OK.
If voltage is 12.5 volts or less, the stator or diode
are probably faulty. Test the stator and diode
(Tests 2, 3 and 4).
2. Disconnect the charging lead from battery.
No
Charge
to
Battery
With engine running at 3000 RPM, measure
voltage from charging lead to ground using a
DC voltmeter.
3. With charging lead disconnected from battery
and engine stopped, measure resistance from
charging lead to ground using an ohmmeter.
Note reading.
2. If voltage is 28 volts or more, stator winding is
OK.
If voltage is less than 28 volts, test stator using
an ohmmeter (Tests 3 and 4).
3. If resistance is low in both directions, the diode
is shorted. Replace the diode.
If resistance is high in both directions, the diode
or stator winding is open. (Use Test 4.)
Reverse the leads and measure resistance
again.
In one direction, the resistance should be
infinity ohms (open circuit). With the leads
reversed, some resistance should be measured
(about midscale on Rx1 range).
4. Cut the sleeving on the charging lead to
expose the diode connections.
Measure the resistance from the stator side of
diode to ground using an ohmmeter.
8
4. If resistance is approximately 1.07 ohms,
stator winding is OK.
If resistance is 0 ohms, stator winding is
shorted. Replace stator.
If resistance is infinity ohms, stator winding or
lead is open. Replace stator.
No
Lights
1. Make sure lights are not burned out.
1. Replace burned out lights.
2. Disconnect the lighting lead from the wiring
harness.
2. If voltage is 15 volts or more, stator is OK.
Check for loose connections or shorts in wiring
harness.
With engine running at 3000 RPM, measure
voltage from lighting lead to ground using an
AC voltmeter.
If voltage is less than 15 volts, test stator using
an ohmmeter (Test 3).
3. With engine stopped, measure the resistance
3. If resistance is approximately 0.4 ohms,
of stator from lighting lead to ground using an
stator is OK.
ohmmeter.
If resistance is 0 ohms, stator is shorted. Replace
stator.
If resistance is infinity ohms, stator or lighting
lead is open. Replace stator.
8.23
Section 8
Electrical System and Components
Electric Starting Motors
Some engines in this series use inertia drive starting
motors while most use solenoid shift starters. The
inertia drive types are covered first and the solenoid
shift types following.
Starting Motor Precautions
NOTE: Do not crank the engine continuously for
more than 10 seconds at a time. If the engine
does not start, allow a 60-second cool-down
period between starting attempts. Failure to
follow these guidelines can burn out the
starter motor.
NOTE: If the engine develops sufficient speed to
disengage the starter but does not keep
running (a false start), the engine rotation
must be allowed to come to a complete stop
before attempting to restart the engine. If the
starter is engaged while the flywheel is
rotating, the starter pinion and flywheel ring
gear may clash, resulting in damage to the
starter.
NOTE: If the starter does not crank the engine, shut
off the starter immediately. Do not make
further attempts to start the engine until the
condition is corrected.
NOTE: Do not drop the starter or strike the starter
frame. Doing so can damage the starter.
Starter Removal and Installation
Refer to the “Disassembly” and “Reassembly”
Sections for starter removal and installation
procedures.
Inertia Drive Electric Starters
This subsection covers the operation, troubleshooting,
and repair of the inertia drive, and permanent magnet
electric starters.
Troubleshooting Guide – Starting Difficulties
Problem
Possible Fault
Battery
Starter
Does Not
Energize
Starter
Energizes
but Turns
Slowly
Wiring
1. Check the specific gravity of battery. If low, recharge or replace
battery as necessary.
1. Clean corroded connections and tighten loose connections.
2. Replace wires in poor condition and with frayed or broken
insulation.
Starter Switch
or Solenoid
1. By-pass the switch or solenoid with a jumper wire. If starter
cranks normally, replace the faulty components. Solenoid Shift
Starters: Perform individual solenoid test procedure. See pages
8.39 and 8.40.
Battery
1. Check the specific gravity of battery. If low, recharge or replace
battery as necessary.
Brushes
1. Check for excessively dirty or worn brushes and commutator.
Clean using a coarse cloth (not emery cloth).
2. Replace brushes if excessively or unevenly worn.
Transmission
or
Engine
8.24
Correction
1. Make sure the clutch or transmission is disengaged or placed in
neutral. This is especially important on equipment with
hydrostatic drive. The transmission must be exactly in neutral to
prevent resistance which could keep the engine from starting.
2. Check for seized engine components such as the bearings,
connecting rod, and piston.
Section 8
Electrical System and Components
Operation - Inertia Drive Starters
When power is applied to the starter, the armature
rotates. As the armature rotates, the drive pinion
moves out on the drive shaft splines and into mesh
with the flywheel ring gear. When the pinion reaches
the end of the drive shaft, it rotates the flywheel and
“cranks” the engine.
7. Install the drive pinion, dust cover spacer, antidrift spring, stop gear spacer, and stop nut.
Torque the stop nut to 17.0-19.2 N·m
(150-170 in. lb.). Reinstall the dust cover.
Style ‘‘A’’
Dust Cover
When the engine starts, the flywheel rotates faster
than the starter armature and drive pinion. This moves
the drive pinion out of mesh with the ring gear and
into the retracted position. When power is removed
from the starter, the armature stops rotating and the
drive pinion is held in the retracted position by the
anti-drift spring.
Starter Drive Service
Every 500 hours of operation (or annually, whichever
occurs first), clean and lubricate the splines on the
starter drive shaft. If the drive pinion is worn, or has
chipped or broken teeth, it must be replaced. See
Figure 8-34.
Stop Nut
Stop Gear Spacer
Anti-Drift Spring
Dust Cover
Spacer
Style ‘‘B’’
Dust Cover
Retaining Ring
Spring Retainer
Anti-Drift Spring
Dust Cover Spacer
Drive Pinion
Drive Pinion
Drive Nut (Collar)
It is not necessary to completely disassemble the
starter to service the drive components.
Style ‘‘A’’ Drive Service
1. Remove the starter from the engine and remove
the dust cover.
8
2. Hold the drive pinion in a vice with soft jaws
when removing or installing the stop nut. The
armature will rotate with the nut until the drive
pinion stops against internal spacers.
NOTE: Do not over-tighten the vise as this can
distort the drive pinion.
3. Remove the stop nut, stop gear spacer, anti-drift
spring, dust cover spacer, and drive pinion.
4. Clean the splines on the drive shaft thoroughly
with solvent. Dry the splines thoroughly.
5. Apply a small amount of Kohler electric starter
drive lubricant, (see Section 2) to the splines. The
use of other lubricants may cause the drive pinion
to stick or bind.
6. Apply a small amount of Loctite® No. 271 to the
stop nut threads.
Style ‘‘A’’
Style ‘‘B’’
Figure 8-34. Inertia Drive Electric Starter.
8.25
Section 8
Electrical System and Components
Style ‘‘B’’ Drive Service
1. The rubber dust cover has a molded lip on the
inside that snaps into a groove in the dust cover
spacer (see Figure 8-35). Turn the drive pinion
clockwise until it reaches the fully extended
position. While holding it in the extended
position, grasp the tip of the dust cover with a
pliers or vise grip and pull it free from the spacer.
Dust Cover
Spring
Retainer
Retaining
Ring
Anti-Drift
Spring
Dust Cover
Spacer
Drive
Pinion
Figure 8-36. Assembling Inner Half of Tool Around
Armature Shaft and Retaining Ring.
5. Thread the center screw into the removal tool
until you feel resistance. Use a wrench (1-1/8" or
adjustable) to hold the base of the removal tool.
Use another wrench or socket (1/2" or 13 mm) to
turn the center screw clockwise (see Figure 8-37).
The resistance against the center screw will tell
you when the retaining ring has popped out of
the groove in the armature shaft.
Drive Nut
(Collar)
Figure 8-35. Drive Components, ‘‘Bonded’’ Inertia
Drive Starter.
2. Disassemble the snap ring removal tool (see
Section 2).
3. Again referring to Figure 8-35, grasp the spring
retainer and push it toward the starter,
compressing the anti-drift spring and exposing
the retaining ring.
4. Holding the spring retainer in the retracted
position, assemble the inner halves of the removal
tool around the armature shaft with the retaining
ring in the inner groove (see Figure 8-36). Slide
the collar over the inner halves to hold them in
position.
8.26
Figure 8-37. Holding Tool and Turning Center
Screw (Clockwise) to Remove Retaining Ring.
6. Remove the drive components from the armature
shaft, paying attention to the sequence. If the
splines are dirty, clean them with solvent.
7. The splines should have a light film of lubricant.
Relubricate as necessary with Kohler starter drive
lubricant (see Section 2). Reinstall or replace the
drive components, assembling them in the
reverse order they were removed.
Section 8
Electrical System and Components
Retaining Ring Installation
1. Position the retaining ring in the groove in one of
the inner halves. Assemble the other half over the
top and slide on the outer collar.
2. Be certain the drive components are installed in
correct sequence onto the armature shaft.
3. Slip the tool over the end of the armature shaft, so
the retaining ring inside is resting on the end of
the shaft. Hold the tool with one hand, exerting
slight pressure toward the starter. Tap the top of
the tool with a hammer until you feel the
retaining ring snap into the groove. Disassemble
and remove the tool.
4. Squeeze the retaining ring with a pliers to
compress it into the groove.
5. Assemble the inner halves with the larger cavity
around the spring retainer (see Figure 8-38). Slide
the collar over them and thread the center screw
in until resistance is felt.
Starter Disassembly
1. Remove the drive components following the
instructions for servicing the drive.
2. Locate the small raised line on the edge of the
drive end cap. On starters with Style ‘‘A’’
commutator end caps, it will be aligned with a
pre-marked line on the starter frame. The frame is
not pre-marked on starters with Style ‘‘B’’ end
caps. Place a piece of masking tape on the frame
and mark a line on the tape in line with the raised
line on the end cap. See Figure 8-41.
3. Remove the thru bolts.
4. Remove the commutator end cap with brushes and
brush springs (Style ‘‘A’’). Style ‘‘B’’ end caps
remove as a separate piece with the brushes and
carrier remaining in the frame.
5. Remove the drive end cap.
6. Remove the armature and thrust washer (if so
equipped) from inside the starter frame.
7. Remove the brush/carrier assembly from the frame
(Style ‘‘B’’ starters).
Style ‘‘A’’ End Cap Brush Replacement
1. Remove the brush springs from the pockets in the
brush holder. See Figure 8-39.
2. Remove the self-tapping screws, negative (-)
brushes, and plastic brush holder.
3. Remove the hex flange nut and fiber washer from
the stud terminal.
Figure 8-38. Assembling Larger Inner Half Around
Spring Retainer.
6. Hold the base of the tool with a 1-1/8" wrench
and turn the center screw clockwise with a 1/2" or
13 mm wrench to draw the spring retainer up
around the retaining ring. Stop turning when
resistance increases. Disassemble and remove the
tool.
7. Reinstall the dust cover.
Remove the stud terminal with the positive (+)
brushes and plastic insulating bushing from the
end cap.
4. Install the insulating bushing on the stud terminal
of the new positive (+) brushes. Install the stud
terminal into the commutator end cap. Secure the
stud with the fiber washer and hex flange screw.
5. Install the brush holder, new negative (-) brushes,
and self-tapping screws.
6. Install the brush springs and brushes into the
pockets in the brush holder. Make sure the
chamfered sides of the brushes are away from the
brush springs.
8.27
8
Section 8
Electrical System and Components
NOTE: Use a brush holder tool to keep the
brushes in the pockets. A brush holder
tool can easily be made from thin sheet
metal. See Figure 8-40.
2. Insert the armature into the starter frame. Make
sure the magnets are closer to the drive shaft end
of the armature. The magnets will hold the
armature inside the frame.
SelfTapping
Screw
3. Install the drive end cap over the drive shaft.
Make sure the match marks on the end cap and
starter frame are aligned. See Figure 8-41.
Brush Springs
Brush
Holder
Negative
(-) Brush
Negative
(-) Brush
Self-Tapping
Screw
Stud Terminal with
Positive (+) Brushes
Figure 8-39. Style ‘‘A’’ Commutator End Cap with
Brushes.
Brush Holder Tool Installed
Over Brushes and End Cap
2 1/2"
1/2"
1 3/4"
1"
Sheet Metal Brush
Holder Tool
Figure 8-40. Brush Holder Tool (Style ‘‘A’’ End Cap).
Style ‘‘B’’ End Cap Brush Replacement
Starters with Style ‘‘B’’ end caps have the brushes in a
plastic carrier housing, separate from the end cap.
Replacement brushes come preassembled in the carrier
housing, retained with two carton staples.
Commutator Service
Clean the commutator with a coarse, lint free cloth. Do
not use emery cloth.
If the commutator is badly worn or grooved, turn it
down on a lathe or replace the starter.
Starter Reassembly
1. Place the thrust washer (if so equipped) over the
drive shaft of the armature.
8.28
Figure 8-41. Starter Assembly Match Marks.
For Style ‘‘A’’ Commutator End Caps:
4. Install the brush holder tool to keep the brushes
in the pockets of the commutator end cap.
5. Align the match marks on the commutator end
cap and the starter frame. Hold the drive end and
the commutator end caps firmly to the starter
frame. Remove the brush holder tool.
For Style ‘‘B’’ Commutator End Caps:
4. If the brush assembly is not being replaced,
position the brushes in their pockets in the
carrier. Move them to the retracted position, and
install carton staples to retain them. See Figure
8-42.
5. Align the terminal stud block with the notch in
the starter frame and slide the brush/carrier
assembly into the frame. The commutator will
push the carton staples out as the brush assembly
is installed. Position the end cap over the brush
assembly, so the holes for the thru bolts are
aligned with those in the brush carrier.
Section 8
Electrical System and Components
Solenoid Shift Electric Starters
The following subsection covers the solenoid shift
electric starters. Much of the information in the
proceeding subsection relates to this type starter also,
so it is not repeated here. A Nippondenso or DelcoRemy solenoid shift starter may be used. The
Nippondenso starter is covered first, and the DelcoRemy starter servicing follows.
Figure 8-42. Style ‘‘B’’ Commutator End Cap with
Brushes.
6. Install the thru bolts and tighten securely.
7. Lubricate the drive shaft with Kohler starter drive
lubricant (see Section 2). Install the drive
components following the instructions for
servicing the starter drive.
Nut
Operation – Solenoid Shift Starter
When power is applied to the starter the electric
solenoid moves the drive pinion out onto the drive
shaft and into mesh with the flywheel ring gear. When
the pinion reaches the end of the drive shaft it rotates
the flywheel and cranks the engine.
When the engine starts and the start switch is released
the starter solenoid is deactivated, the drive lever
moves back, and the drive pinion moves out of mesh
with the ring gear into the retracted position.
Drive End Cap
Frame
8
Wire
Drive
Lever
Front Stop
Collar
Dust
Cover
Starter Assembly
Retainer
Rear Stop
Collar
Brushes
Brush
Holder
Brush Spring
Solenoid
Insulator
Nut
Drive
Pinion
Commutator
End Cap
Thru Bolt
Armature
Figure 8-43. Nippondenso Solenoid Shift Starter.
8.29
Section 8
Electrical System and Components
Starter Disassembly
1. Disconnect the lead wire from the solenoid.
2. Remove the hex nuts securing the solenoid, and
remove the solenoid from the starter assembly.
3. Remove the two thru bolts.
4. Remove the commutator end cap.
5. Remove the insulator and the brush springs from
the brush spring holder.
Starter Service
Every 500 hours of operation (or annually, whichever
comes first), solenoid shift starters must be
disassembled, cleaned and relubricated. Apply starter
lubricant (see Section 2) to the lever and shaft. Failure
to do so could result in an accumulation of dirt or
debris that might prevent the engine from starting and
could cause damage to the starter or the flywheel.
Service may be necessary more frequently under
dusty or dirty conditions.
Starter Reassembly
1. Insert the rear stop collar on the armature shaft.
6. Remove the armature from the frame.
7. Remove the drive lever and the armature from
the drive end cap.
NOTE: When removing the lever and the
armature be careful not to lose the thrust
washer.
8. The stop collar consists of two similar pieces held
in place by being snapped over a retainer. The
retainer is held in place by a groove in the
armature shaft. To remove the stop collar the two
pieces must be pried off the retainer.
9. When the stop collars are removed the retainer
can be removed from the armature shaft. Do not
reuse the retainer.
2. Place the retainer in the groove on the armature
shaft.
NOTE: Always use a new retainer. Tighten the
retainer in the groove to secure.
3. Fit the front stop collar over the shaft and bring
the front and the rear stop collars together over
the retainer. Using two pairs of pliers apply even
force to the two collars until they snap over the
retainer and nest into one another.
4. Reassemble the remaining components of the
starter in reverse order from disassembly.
Delco-Remy Starters
Brush Replacement
The brushes in the starter are part of the starter frame.
Brush kit, Kohler Part No. 52 221 01-S, contains four
replacement brushes and springs. If replacement is
necessary, all four brushes should be replaced.
1. Remove the brushes from the brush holder, and
remove the brush holder from the frame.
2. Cut the brush lead wire at the edge of the post
with a pair of nippers.
3. File off any burrs on the post.
4. The replacement brushes have a solid portion
which should be crimped on the post.
5. Solder the crimped portion to the post.
6. Replace the brush holder in the frame and place
the brushes in the brush holder. Reinstall the
springs.
8.30
Figure 8-44. Completed Delco-Remy Starter.
Starter Disassembly
1. Remove the hex nut and disconnect the positive
(+) brush lead/bracket from the solenoid terminal.
2. Remove the three screws securing the solenoid to
the starter. See Figure 8-45.
Section 8
Electrical System and Components
Phillips Head
Screws
Torx Head Screws
Figure 8-45. Removing Solenoid Screws.
Figure 8-46. Solenoid Removed from Starter.
8
3. If the solenoid was mounted with Phillips head
screws, separate the solenoid and plunger spring
from the drive end cap. If the solenoid was
mounted with external Torx head screws, the
plunger is part of the solenoid, unhook the
plunger pin from the drive lever. Remove the
gasket from the recess in the housing. See Figures
8-46 and 8-47.
NOTE: Test procedure for checking starter solenoid
on pages 8.39 and 8.40.
Figure 8-47. Removing Plunger.
4. Remove the two thru (larger) bolts. See Figure
8-48.
8.31
Section 8
Electrical System and Components
7. Remove the drive lever pivot bushing and
backing plate from the end cap. See Figure 8-51.
Figure 8-48. Removing Thru Bolts.
5. Remove the commutator end plate assembly,
containing the brush holder, brushes, springs,
and locking caps. Remove the thrust washer from
inside the commutator end. See Figure 8-49.
Figure 8-51.
8. Take out the drive lever and pull the armature out
of the drive end cap. See Figure 8-52.
9. Remove the thrust washer from the armature
shaft. See Figure 8-52.
Figure 8-49. Removing Commutator End Plate
Assembly.
6. Remove the frame from the armature and drive
end cap. See Figure 8-50.
Figure 8-52. Armature and Lever Removed.
10. Push the stop collar down to expose the retaining
ring. See Figure 8-53.
Figure 8-50. Starter Frame Removed.
8.32
Section 8
Electrical System and Components
Figure 8-53. Retaining Ring Detail.
Figure 8-54. Removing Retaining Ring.
11. Remove the retainer from the armature shaft.
Save the stop collar.
12. Remove the drive pinion assembly from the
armature.
NOTE:
13. Clean the parts as required.
Do not reuse the old retainer.
NOTE: Do not soak the armature or use solvent
when cleaning. Wipe clean using a soft cloth,
or use compressed air.
Screw
8
Collar
Ring
Stop
Drive
Plunger
Spring
Lever
Plate
Plug
Armature
Solenoid
Frame & Field
Washer
Tube
Brush Holder
Nut
CE Frame
Screw
Bolt
Figure 8-55. Delco-Remy Starter.
8.33
Section 8
Electrical System and Components
Inspection
Commutator O.D.
Drive Pinion
Check and inspect the following areas:
a. The pinion teeth for abnormal wear or damage.
b. The surface between the pinion and the clutch
mechanism for nicks, or irregularities which
could cause seal damage.
c. Check the drive clutch by holding the clutch
housing and rotating the pinion. The pinion
should rotate in one direction only.
Brushes and Springs
Inspect both the springs and brushes for wear, fatigue,
or damage. Measure the length of each brush. The
minimum length for each brush is 7.6 mm (0.300 in.).
See Figure 8-56. Replace the brushes if they are worn
undersize, or their condition is questionable.
Mica Insulation
Figure 8-57. Commutator Mica Inspection.
2. Use an ohmmeter set to the Rx1 scale. Touch the
probes between two different segments of the
commutator, and check for continuity. See Figure
8-58. Test all the segments. Continuity must exist
between all or the armature is bad.
Insulation
Check
Wear limit length:
7.6 mm (0.300 in.)
Figure 8-56. Checking Brushes.
Armature
1. Clean and inspect the commutator (outer
surface). The mica insulation must be lower than
the commutator bars (undercut) to ensure proper
operation of the commutator. See Figure 8-57.
Armature
Coil
Continuity Check
Figure 8-58. Checking Armature.
3. Check for continuity between the armature coil
segments and the commutator segments. See
Figure 8-58. There should be no continuity. If
continuity exists between any two, the armature
is bad.
4. Check the armature windings/insulation for
shorting.
Shift Fork
Check that the shift fork is complete, and the pivot
and contact areas are not excessively worn, cracked or
broken.
8.34
Section 8
Electrical System and Components
Brush Replacement
Starter Service
The brushes and springs are serviced as a set (4). Use
Brush and Spring Kit, Kohler Part No. 25 221 01-S, if
replacement is necessary.
Clean the drive lever and armature shaft. Apply
Kohler electric starter drive lubricant (see Section 2)
(Versilube G322L or Mobil Temp SHC 32) to the lever
and shaft. Clean and check the other starter parts for
wear or damage as required.
1. Perform steps 1-5 in “Starter Disassembly.”
2. Remove the two screws securing the brush holder
assembly to the end cap (plate). Note the
orientation for reassembly later. See Figure 8-59.
Discard the old brush holder assembly.
Starter Reassembly
1. Apply drive lubricant (see Section 2) to the
armature shaft splines. Install the drive pinion
onto the armature shaft.
2. Install and assemble the stop collar/retainer
assembly.
a. Install the stop collar down onto the armature
shaft with the counter bore (recess) up.
b. Install a new retainer in the larger (rear)
groove of the armature shaft. Squeeze with a
pliers to compress it in the groove.
Figure 8-59. Removing Brush Holder.
c. Slide the stop collar up and lock it into place,
so the recess surrounds the retainer in the
groove. If necessary, rotate the pinion outward
on the armature splines against the retainer to
help seat the collar around the retainer.
8
3. Clean the component parts as required.
4. The new brushes and springs come preassembled
in a brush holder with a protective sleeve that
will also serve as an installation tool. See Figure
8-60.
Figure 8-61. Installing Stop Collar and Retainer.
NOTE: Always use a new retainer. Do not reuse old
retainers, which have been removed.
Figure 8-60. Service Brush Kit.
3. Install the offset thrust (stop) washer so the
smaller “offset” of the washer faces the retainer/
collar. See Figure 8-62.
5. Perform Steps 10-13 in the “Starter Reassembly”
sequence. Installation must be done after the
armature, drive lever, and frame are installed, if
the starter has been disassembled.
8.35
Section 8
Electrical System and Components
7. Install the backup washer, followed by the rubber
grommet, into the matching recess of the drive
end cap. The molded recesses in the grommet
should be “out”, matching and aligned with
those in the end cap. See Figure 8-64.
Figure 8-62. Installing Thrust Washer.
4. Apply a small amount of oil to the bearing in the
drive end cap, and install the armature with the
drive pinion.
5. Lubricate the fork end and center pivot of the
drive lever with drive lubricant (see Section 2).
Position the fork end into the space between the
captured washer and the rear of the pinion.
6. Slide the armature into the drive end cap, and at
the same time seat the drive lever into the
housing.
Figure 8-64. Installing Backup Washer and
Grommet.
8. Install the frame, with the small notch forward,
onto the armature and drive end cap. Align the
notch with the corresponding section in the
rubber grommet. Install the drain tube in the rear
cutout, if it was removed previously. See Figure
8-65.
NOTE: Correctly installed, the center pivot section of
the drive lever will be flush or below the
machined surface of the housing which
receives the backup washer. See Figure 8-63.
Figure 8-65. Installing Frame and Drain Tube.
9. Install the flat thrust washer onto the commutator
end of the armature shaft. See Figure 8-66.
Figure 8-63. Installing Armature and Pivot Lever.
8.36
Section 8
Electrical System and Components
Figure 8-66. Installing Thrust Washer.
10. Starter reassembly when replacing the Brushes/
Brush Holder Assembly:
a. Hold the starter assembly vertically on the
end housing, and carefully position the
assembled brush holder assembly, with the
supplied protective tube, against the end of
the commutator/armature. The mounting
screw holes in the metal clips must be “up/
out.” Slide the brush holder assembly down
into place around the commutator, and install
the positive (+) brush lead grommet in the
cutout of the frame. See Figure 8-67. The
protective tube may be saved and used for
future servicing.
Figure 8-68. Removing Retaining Clips.
b. Position each of the brushes back in their slots
so they are flush with the I.D. of the brush
holder assembly. Insert the Brush Installation
Tool with extension, or use the tube described
above from a prior brush installation, through
the brush holder assembly, so the holes in the
metal mounting clips are “up/out.”
c. Install the brush springs and snap on the four
retainer caps. See Figure 8-69.
8
Figure 8-69. Brush Installation Tool with Extension.
Figure 8-67. Installing Brush Holder Assembly with
Supplied Tube.
Starter reassembly when not replacing the Brushes/
Brush Holder Assembly:
d. Hold the starter assembly vertically on the end
housing, and carefully place the tool (with
extension) and assembled original brush holder
assembly onto the end of the armature shaft.
Slide the brush holder assembly down into
place around the commutator, install the
positive (+) brush lead grommet in the cutout
of the frame. See Figure 8-70.
a. Carefully unhook the retaining caps from over
each of the brush assemblies. Do not lose the
springs.
8.37
Section 8
Electrical System and Components
Figure 8-70. Installing Brush Holder Assembly
using Tool with Extension.
11. Install the end cap onto the armature and frame,
aligning the thin raised rib in the end cap with
the corresponding slot in the grommet of the
positive (+) brush lead.
12. Install the two thru bolts, and the two brush
holder mounting screws. Torque the thru bolts to
5.6-9.0 N·m (49-79 in. lb.). Torque the brush
holder mounting screws to 2.5-3.3 N·m
(22-29 in. lb.). See Figures 8-71 and 8-72.
Figure 8-72. Torquing Brush Holder Screws.
13. Hook the plunger behind the upper end of the
drive lever, and install the spring into the
solenoid. Insert the three mounting screws
through the holes in the drive end cap. Use these
to hold the solenoid gasket in position, then
mount the solenoid. Torque the screws to
4.0-6.0 N·m (35-53 in. lb.).
14. Connect the positive (+) brush lead/bracket to the
solenoid and secure with the hex nut. Torque the
nut to 8-11 N·m (71-97 in. lb.). Do not
overtighten. See Figure 8-73.
Figure 8-71. Torquing Thru Bolts.
Figure 8-73. Positive (+) Brush Lead Connection.
8.38
Section 8
Electrical System and Components
Solenoid Test Procedure
Solenoid Shift Style Starters
Disconnect all leads from the solenoid including the
positive brush lead attached to the lower stud
terminal. Remove the mounting hardware and
separate the solenoid from the starter for testing.
Test 1. Solenoid Pull-In Coil/Plunger Actuation
Test.
Use a 12 volt power supply and two test leads.
Connect one lead to the flat spade “S/start” terminal
on the solenoid. Momentarily* connect the other lead
to the lower large post terminal. See Figure 8-74.
When the connection is made the solenoid should
energize (audible click), and the plunger retract.
Repeat the test several times. If the solenoid fails to
activate, it should be replaced.
*NOTE: DO NOT leave the 12 volt test leads
connected to the solenoid for any time over
what is necessary for performing each of the
individual tests. Internal damage to the
solenoid may otherwise occur.
12 volt Test Leads
Momentary
Connection Only
VOM Leads
Figure 8-75. Testing Pull-In Coil/Solenoid Contact
Continuity.
Test 3. Solenoid Hold-In Coil Function Test.
Connect one 12 volt test lead to the flat spade “S/start”
terminal on the solenoid, and the other lead to the
body or mounting surface of the solenoid. Then,
manually push the plunger “In” and check if the
“Hold-In” coil holds the plunger retracted. See Figure
8-76. Do not allow the test leads to remain connected
to the solenoid for a prolonged period of time. If the
plunger fails to stay retracted, the solenoid should be
replaced.
8
Manually Push
Plunger “In”
12 volt Test Leads
Momentary
Connection Only
Figure 8-74. Testing Pull-In Coil/Plunger Actuation.
Test 2. Solenoid Pull-In Coil/Contact Continuity
Test.
Use an ohmmeter set to the audible or Rx2K scale, and
connect the two ohmmeter leads to the two large post
terminals. Perform the preceding test (1) and check for
continuity. See Figure 8-75. The ohmmeter should
indicate continuity, if no continuity is indicated the
solenoid should be replaced. Repeat test several times
to confirm condition.
12 volt Test Leads
Connect Only Long
Enough to Test
Figure 8-76. Testing Hold-In Coil/Function Test.
8.39
Section 8
Electrical System and Components
Test 4. Solenoid Hold-In Coil/Contact Continuity
Test.
Use an ohmmeter set to the audible or Rx2K scale, and
connect the two ohmmeter leads to the two large post
terminals. Perform the preceding test (3) and check for
continuity. See Figure 8-77. The meter should indicate
continuity, if no continuity is indicated the solenoid
should be replaced. Repeat test several times to
confirm condition.
Plunger
Pushed “In”
VOM Meter
Leads
12 volt Test Leads
Figure 8-77. Testing Hold-In Coil/Solenoid Contact
Continuity.
8.40
Section 9
Disassembly
Section 9
Disassembly
WARNING: Accidental Starts!
Disabling engine. Accidental starting can cause severe
injury or death. Before working on the engine or
equipment, disable the engine as follows: 1) Disconnect the
spark plug lead(s). 2) Disconnect negative (-) battery cable
from battery.
General
Clean all parts thoroughly as the engine is
disassembled. Only clean parts can be accurately
inspected and gauged for wear or damage. There are
many commercially available cleaners that will
quickly remove grease, oil and grime from engine
parts. When such a cleaner is used, follow the
manufacturer’s instructions and safety precautions
carefully.
Make sure all traces of the cleaner are removed before
the engine is reassembled and placed into operation.
Even small amounts of these cleaners can quickly
break down the lubricating properties of engine oil.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
Remove valve covers.
Remove ignition modules.
Remove intake manifold.
Remove spark plugs.
Remove cylinder heads and hydraulic lifters.
Remove grass screen and fan.
Remove flywheel.
Remove stator and backing plates.
Remove oil pan assembly.
Remove camshaft.
Remove governor cross shaft.
Remove connecting rods with pistons and rings.
Remove crankshaft.
Remove flywheel end oil seal.
Disconnect Spark Plug Leads
1. Disconnect the leads from the spark plugs. See
Figure 9-1.
NOTE: Pull on boot only, to prevent damage to
spark plug lead.
Typical Disassembly Sequence
The following sequence is suggested for complete
engine disassembly. The sequence can be varied to
accommodate options or special equipment.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Disconnect spark plug leads.
Shut off fuel supply.
Drain oil from crankcase and remove oil filter.
Remove oil cooler.
Remove muffler.
Remove air cleaner assembly.
Remove control panel.
Remove fuel pump.
Remove throttle controls.
Remove external governor controls.
Remove carburetor.
Remove electric starter motor.
Remove outer baffles and blower housing.
Remove Oil Sentry™.
Remove inner baffles and breather cover.
Figure 9-1. Disconnect Spark Plug Leads.
Shut Off Fuel Supply
Drain Oil From Crankcase and Remove
Oil Filter
1. Remove oil fill cap/dipstick and one of the oil
drain plugs.
9.1
9
Section 9
Disassembly
3. Remove the mounting screw and detach the oil
fill tube. See Figure 9-3.
4. Remove and discard the oil filter. See Figure 9-4.
Remove Oil Cooler
If equipped, the oil cooler can now be removed from
the engine. Two different styles are used, see Figures
6-6 and 6-7 in Section 6.
1. Use a 5/16" allen wrench to remove the oil filter
nipple.
Figure 9-2. Removing Oil Fill Cap/Dipstick.
2. For the crankcase-mounted cooler: Separate the
oil cooler from the oil pan. Remove and discard
the gasket located between them.
For the blower housing-mounted cooler:
Separate the filter adapter from the oil pan,
leaving the oil lines attached. Remove the two hex
flange screws mounting the oil cooler to the
blower housing. Remove the cooler, lines, and
filter adapter as an assembly.
Remove Muffler
1. Remove the exhaust system and attaching
hardware from the engine. On engines equipped
with a port liner, remove it now.
Figure 9-3. Removing Oil Fill Tube Bracket.
Remove Air Cleaner Assembly
Standard Air Cleaner
1. Unhook the latches located on either side of the
air cleaner cover, or loosen the cover-retaining
knob, and remove the cover. See Figure 9-5.
Figure 9-4. Removing Oil Filter.
2. Allow ample time for the oil to drain from the
crankcase and oil filter.
Figure 9-5. Removing Standard Air Cleaner Cover.
2. Remove the wing nut from the element cover.
9.2
Section 9
Disassembly
Figure 9-6. Removing Standard Element and
Precleaner.
Figure 9-8. Removing Commercial Mower Element
and Precleaner.
3. Remove the element cover, element and
precleaner. See Figure 9-6.
Hex Flange
Nuts (2)
Lower Mounting
Screws (Some
Models)
9
Figure 9-7. Removing Standard Air Cleaner Base.
4. Remove the two hex flange nuts securing the
spitback cup, baffle or bracket, and air cleaner
base. See Figure 9-7. Two additional lower screws
must be removed if the engine contains a lower
air cleaner support bracket.
Figure 9-9. Disconnect Breather Hose from Base.
5. Disconnect the breather tube from the nipple on
the underside, or the hose from the base (as
equipped). See Figure 9-9.
6. Remove the base and gasket while carefully
pulling the rubber breather tube through the
base.
9.3
Section 9
Disassembly
Heavy Duty Air Cleaner
1. Disconnect the breather hose from the fitting in
adapter or elbow. Remove the hex flange nuts
securing the adapter and any attached clips to the
mounting studs. See Figure 9-10.
4. Remove the two upper screws securing the air
cleaner mounting bracket to the blower housing
and remove the air cleaner assembly. See Figures
9-12 and 9-13.
Adapter Elbow
Hex
Nuts
Upper Mounting Screws
Breather
Hose
Figure 9-12. Removing Upper Mounting Screws.
Figure 9-10. Removing Breather Hose, Hex Nuts
and Adapter Elbow (Two-Barrel Model Pictured).
2. Pull the adapter elbow and gasket off the
mounting studs.
3. Remove the four screws (inner two valve cover
screws on each side) securing the air cleaner main
support bracket. Do not lose any of the mounting
hardware.
Two-Barrel Carburetor Models only: Unhook the
choke return spring from the bottom of the air
cleaner mounting bracket. See Figure 9-11.
Figure 9-13. Removing Heavy Duty Air Cleaner
Assembly (Two-Barrel Model Pictured).
Choke Return Spring
Remove Control Panel (If So Equipped)
1. Disconnect the Oil Sentry™ Indicator Light wires.
2. Disconnect the choke control cable from the
throttle control bracket.
3. Disconnect the throttle control bracket from the
cylinder head. See Figure 9-14.
Main Bracket Mounting Screws
Figure 9-11. Air Cleaner Bracket/Valve Cover
Mounting Screws (Two-Barrel Model Pictured).
9.4
4. Remove the panel from the blower housing. See
Figure 9-15.
Section 9
Disassembly
Pulse
Hose
Figure 9-14. Removing Throttle Control Bracket.
Figure 9-16. Disconnecting Pulse Line from
Crankcase.
Fuel Pump
Inlet Hose
Outlet Hose
(To Carburetor)
Pulse
Hose
Figure 9-15. Removing Control Panel.
Mounting Screws
Figure 9-17. Pulse Fuel Pump Details.
9
Remove Fuel Pump
WARNING: Explosive Fuel!
Gasoline may be present in the carburetor and fuel system.
Gasoline is extremely flammable and its vapors can explode
if ignited. Keep sparks, open flames and other sources of
ignition away from the engine.
1. Disconnect the fuel lines at the carburetor and at
the in-line fuel filter.
2. Disconnect the pulse (vacuum) hose from the
crankcase. See Figure 9-16.
3. Remove the two hex flange mounting screws
from the blower housing and remove the fuel
pump and lines as an assembly. See Figure 9-17.
Remove Throttle Controls
1. Remove the four hex flange screws securing the
throttle control bracket and lower air cleaner
bracket (some models), to the cylinder heads. See
Figures 9-18 and 9-19.
9.5
Section 9
Disassembly
Control Bracket
Figure 9-18. Removing Control Bracket.
Air Cleaner Brackets
(Some Models)
Governor Lever
Figure 9-20. Removing Governor Lever.
Remove Carburetor
WARNING: Explosive Fuel!
Gasoline may be present in the carburetor and fuel system.
Gasoline is extremely flammable, and its vapors can explode
if ignited. Keep sparks and other sources of ignition away
from the engine.
1. Disconnect the fuel shut-off solenoid lead if so
equipped.
Control Bracket
Fuel Solenoid
Lead
Ground Lead
Figure 9-19. Removing Control Bracket and Air
Cleaner Bracket (Some Models).
2. Disconnect the spring from the governor lever;
note hole locations for reassembly.
3. Remove the choke linkage from the choke
actuator lever and carburetor.
Remove External Governor Controls
1. Loosen the hex flange nut and remove the
governor lever from the cross shaft. See Figure
9-20. Leave the lever attached to the throttle
linkage.
Figure 9-21. Removing Fuel Solenoid and Ground
Leads (Two-Barrel Model Pictured).
2. Remove the carburetor mounting nuts. See Figure
9-21.
9.6
Section 9
Disassembly
3. Remove the carburetor, throttle linkage and
governor lever as an assembly.
5. If necessary, the carburetor, throttle linkage and
governor lever can be separated. Reattach the
bushings to the linkage following separation to
avoid losing them.
Remove Electric Starter Motor
1. Disconnect the leads from the starter.
2. Remove the two hex flange screws. See Figure
9-25.
Figure 9-22. Removing Carburetor and Linkage
(Two-Barrel Model Pictured).
Figure 9-25. Removing Electric Starter Motor.
3. Remove the starter assembly and lift bracket.
Some inertia drive starters use a separate starter
cover and spacers.
9
Figure 9-23. Removing Carburetor Mounting Nuts
(Commercial Mower Base Shown).
Figure 9-24. Removing Carburetor.
4. Remove the carburetor gasket.
9.7
Section 9
Disassembly
Remove Outer Baffles and Blower
Housing
1. Disconnect the wire leads from the start switch
on the blower housing (if so equipped).
Disconnect the plug from the rectifier-regulator.
Use the tip of the dipstick or a similar small flat
tool to bend the locking tang, then remove the B+
terminal from the center position in the plug. See
Figure 9-26. This will allow the blower housing to
be removed without disturbing the wiring
harness.
Figure 9-27. Loosening Spark Advance Module
(Applicable Models).
Short
Screw
Figure 9-26. Disconnecting Plug from RectifierRegulator.
2. The rectifier-regulator does not have to be
detached from the blower housing. If the engine
is equipped with SMART-SPARK™, remove the
mounting screws from the spark advance module
(SAM). See Figure 9-27. The module will hang
loose as part of the wiring harness.
Figure 9-28. Note Location of Short Screws.
4. Remove the outer baffles. See Figure 9-29.
3. Remove the three (each side) hex flange screws
securing the outer baffles. Note the location of
any lifting strap and the position of the two short
screws (one each side on bottom) for reassembly.
See Figure 9-28.
Figure 9-29. Removing Outer Baffles.
5. If the flywheel screen overlaps the blower
housing, remove the fasteners and screen. If it
was a metal screen with long bolts, also remove
the remaining loose hardware and cooling fan.
See Figure 9-30.
9.8
Section 9
Disassembly
Remove Oil Sentry™
1. Disconnect the lead from the Oil Sentry™ switch.
2. Remove the Oil Sentry™ switch from the breather
cover. See Figure 9-33.
Figure 9-30. Removing Flywheel Screen.
6. Remove the remaining hex flange screws securing
the blower housing. Note the one silver plated
screw used for the rectifier-regulator ground
strap or lead. Remove the blower housing. See
Figures 9-31 and 9-32.
Figure 9-33. Removing Oil Sentry™ Switch.
Remove Inner Baffles and Breather Cover
Ground Strap
1. Remove the four hex flange screws securing the
inner baffles to the crankcase.
2. Remove the inner (valley) baffles. See Figure
9-34.
Silver Screw
9
Figure 9-31. Rectifier-Regulator Ground Strap.
Figure 9-34. Removing Inner Baffles.
3. Remove the two remaining hex flange screws
from the breather cover.
Figure 9-32. Removing Blower Housing.
4. Pry under the protruding edge of the breather
cover with a screwdriver to break the RTV or
gasket seal. See Figure 9-35. Do not pry on the
sealing surfaces as it could cause damage
resulting in leaks. Most engines use a formed
gasket rather than RTV sealant.
9.9
Section 9
Disassembly
Figure 9-35. Break Breather Cover Seal.
5. Remove the breather cover and gasket (if used).
See Figure 9-36.
Figure 9-37. Removing Valve Cover.
Remove Ignition Modules
1. Disconnect the lead(s) from each ignition module.
See Figure 9-38.
SMART-SPARK™
Module Leads
Figure 9-36. Removing Breather Cover Gasket.
Remove Valve Covers
Three valve cover designs have been used. The earliest
type used a gasket and RTV sealant between the cover
and sealing surface of the cylinder head. The second
type had a black O-Ring installed in a groove on the
underside of the cover and may have metal spacers in
the bolt holes. The latest design uses a yellow or
brown O-Ring, and the bolt hole spacers are molded
in place.
1. Remove the four hex flange screws securing each
valve cover. Note valve cover differences for
proper location in reassembly.
2. The O-Ring type covers should lift off without
prying. If loose spacers are present, save them.
With the gasket type, break the seal by carefully
prying under the edges of the cover.
9.10
Fixed Timing
Ignition Module
Kill Lead
Figure 9-38. Disconnect Lead(s) from Ignition
Modules.
2. Rotate the flywheel so the magnet is away from
the modules. See Figure 9-39.
Section 9
Disassembly
Aluminum
Intake
Manifold
Figure 9-39. Position of Ignition Modules.
3. Remove the mounting screws and ignition
modules. Note the position of the ignition
modules.
Remove Intake Manifold
1. Remove the four hex flange screws securing the
intake manifold to the cylinder heads. Note
which screws hold the wiring clamps.
2. Remove the intake manifold and the intake
manifold gaskets (aluminum intake manifolds) or
O-Ring (plastic intake manifolds). See Figure
9-40.
Plastic Intake
Manifold
Figure 9-40. Removing Intake Manifold.
Remove Spark Plugs
3. Leave the wiring harness attached to the
manifold.
1. Remove the spark plug from each cylinder head.
See Figure 9-41.
Figure 9-41. Removing Spark Plugs.
9.11
9
Section 9
Disassembly
Remove Cylinder Heads and Hydraulic
Lifters
NOTE: Cylinder heads are retained using either hex
flange screws or hex flange nuts and washers
on studs. Do not interchange or mix
components, as the cylinder heads may have
different machining, unique to each fastening
method.
1. Remove the four hex flange screws or hex nuts
and washers securing each cylinder head. See
Figure 9-42. Discard the screws or nuts and
washers once removed. Do not reuse. Studs (if
present) should only be removed if damaged or if
cylinder reconditioning is necessary. Once
removed, they must be replaced.
2. Mark the location of the push rods as either
intake or exhaust and cylinder 1 or 2. Push rods
should always be reinstalled in the same
positions.
Figure 9-43. Removing Cylinder Head.
4. Remove the lifters from the lifter bores. Use a
hydraulic lifter tool. Do not use a magnet to
remove lifters. Mark the lifters by location, as
either intake or exhaust, and cylinder 1 or 2.
Hydraulic lifters should always be reinstalled in
the same position. See Figure 9-44.
Hex Flange
Screws
Hydraulic Lifter Tool
Figure 9-44. Removing Hydraulic Lifters.
Disassemble Cylinder Heads
1. Remove the two hex flange screws, rocker arm
pivots and rocker arms from the cylinder head.
See Figure 9-45.
Hex Flange Nuts
and Washers
Figure 9-42. Removing Cylinder Head Fasteners.
3. Carefully remove the push rods, cylinder heads,
and head gaskets. See Figure 9-43.
9.12
Section 9
Disassembly
Valve
Keepers
Cap
Retainer
Spring
Figure 9-45. Removing Rocker Arm.
Figure 9-47. Valve Components.
2. Compress the valve springs using a valve spring
compressor. See Figure 9-46.
Valve Seal
Figure 9-48. Intake Valve Seal Location.
Figure 9-46. Removing Valves with Valve Spring
Compressor.
3. Once the valve spring is compressed, remove the
following items. See Figures 9-47 and 9-48:
•
•
•
•
•
•
Valve spring keepers
Valve spring retainers
Valve springs
Valve spring caps
Intake and exhaust valves (mark position)
Valve stem seal (intake valve only)
NOTE: These engines use valve stem seals on the
intake valves. Use a new seal whenever the
valve is removed or if the seal is deteriorated
or damaged in any way. Never reuse an old
seal.
4. Repeat the above procedure for the other cylinder
head. Do not interchange parts from one cylinder
head to the other.
Remove Grass Screen and Fan
1. On engines with a flat plastic screen, small metal
retainers are typically attached on three of the
seven mounting posts for positive retention of the
plastic grass screen. Use a hook-end tool next to
the post and pull outward to separate each of the
small metal retainers. Then unsnap the screen
from the mounting posts. See Figure 9-49.
9.13
9
Section 9
Disassembly
Figure 9-49. Removing Plastic Grass Screen.
2. Remove the four hex flange screws or hex studs
and washers. Remove the plastic fan from the
flywheel. See Figure 9-50.
Figure 9-51. Removing Flywheel Fastener Using
Strap Wrench.
2. Remove the hex flange screw and washer.
3. Use a puller to remove the flywheel from the
crankshaft. See Figure 9-52.
NOTE: Always use a flywheel puller to remove
the flywheel from the crankshaft. Do not
strike the crankshaft or flywheel, as
these parts could become cracked or
damaged. Striking the puller or
crankshaft can cause the crank gear to
move, affecting crankshaft endplay.
Figure 9-50. Removing Fan.
Remove Flywheel
1. Use a flywheel strap wrench or holding tool (see
Section 2) to hold the flywheel and loosen the hex
flange screw securing the flywheel to the
crankshaft. See Figure 9-51.
NOTE: Always use a flywheel strap wrench or
holding tool to hold the flywheel when
loosening or tightening the flywheel
screw. Do not use any type of bar or
wedge to hold the flywheel. Use of such
tools could cause the flywheel to become
cracked or damaged.
Figure 9-52. Removing Flywheel with a Puller.
4. Remove the woodruff key.
Remove Stator and Backing Plates
1. Remove the four screws securing the backing
plates and stator wire bracket (if so equipped).
See Figure 9-53. Remove the backing plates and
stator wire bracket.
9.14
Section 9
Disassembly
2. Locate the splitting tabs cast into the perimeter of
the oil pan. Insert the drive end of a 1/2" breaker
bar between the splitting tab and the crankcase
and turn it to break the RTV seal. See Figure
9-55. Do not pry on the sealing surfaces as this
can cause leaks.
Governor Gear Assembly
The governor gear assembly is located inside the oil
pan. If service is required, refer to the service
procedures under “Governor Gear Assembly” in
Section 10.
Figure 9-53. Removing Backing Plates and Stator
Wire Bracket.
2. Remove the two hex flange screws and the stator.
See Figure 9-54. Note the position/routing of the
stator lead.
Oil Pump Assembly
The oil pump is mounted inside the oil pan. If service
is required, refer to the service procedures under “Oil
Pump Assembly” in Section 10.
Remove Camshaft
1. Remove the camshaft and shim (if used). See
Figure 9-56.
9
Figure 9-54. Removing Stator.
Figure 9-56. Removing Camshaft.
Remove Oil Pan Assembly
1. Remove the ten hex flange screws securing the oil
pan to the crankcase. See Figure 9-55.
Remove Governor Cross Shaft
1. Remove the hitch pin and plain washer, or the
retainer and nylon washer, from the governor
cross shaft. See Figures 9-57 and 9-58.
Splitting
Tabs
Figure 9-55. Removing Oil Pan Fasteners.
9.15
Section 9
Disassembly
Remove Connecting Rods with Pistons
and Rings
1. Remove the two hex flange screws securing the
closest connecting rod end cap. Remove the end
cap. See Figure 9-60.
Figure 9-57. Removing Governor Cross Shaft Hitch
Pin (6 mm Shaft Design).
Figure 9-60. Removing Connecting Rod End Cap.
NOTE: If a carbon ridge is present at the top of
either cylinder bore, use a ridge reamer
tool to remove it before attempting to
remove the piston.
2. Carefully remove the connecting rod and piston
assembly from the cylinder bore. See Figure 9-61.
Figure 9-58. Removing Governor Cross Shaft
Retainer (8 mm Shaft Design).
2. Remove the cross shaft through the inside of the
crankcase. See Figure 9-59.
Figure 9-59. Removing Governor Cross Shaft.
9.16
NOTE: The cylinders are numbered on the
crankcase. Use the numbers to mark
each end cap, connecting rod and piston
for reassembly. Do not mix end caps and
connecting rods.
Figure 9-61. Removing Connecting Rod and Piston
Assembly.
Section 9
Disassembly
3. Repeat the above procedure for the other
connecting rod and piston assembly.
Remove Crankshaft
Remove Flywheel End Oil Seal
1. Remove the oil seal from the crankcase. See
Figure 9-63.
1. Carefully pull the crankshaft from the crankcase.
See Figure 9-62.
Figure 9-63. Removing Oil Seal.
Figure 9-62. Removing Crankshaft.
9
9.17
Section 10
Inspection and Reconditioning
Section 10
Inspection and Reconditioning
This section covers the operation, inspection, and
repair/reconditioning of major internal engine
components. The following components are not
covered in this section. They are covered in sections of
their own:
Air Cleaner, Section 4
Carburetor & External Governor, Section 5
Ignition, Charging & Electric Starter, Section 8
Operation
The ACR mechanism consists of a flyweight, spring
and pivoting control pin assembly attached to the gear
on the camshaft. At cranking speeds (700 RPM or
lower), the control pin protrudes above the exhaust
cam lobe. This pushes the exhaust valve off its seat
during the first part of the compression stroke. The
reduced compression results in an effective
compression ratio of about 2:1 during cranking.
Clean all parts thoroughly. Only clean parts can be
accurately inspected and gauged for wear or damage.
There are many commercially available cleaners that
will quickly remove grease, oil, and grime from
engine parts. When such a cleaner is used, follow the
manufacturer’s instructions and safety precautions
carefully. Make sure all traces of the cleaner are
removed before the engine is reassembled and placed
into operation. Even small amounts of these cleaners
can quickly break down the lubricating properties of
engine oil.
After starting, engine speed increases to over 700
RPM, and centrifugal force overcomes the force of the
flyweight spring. The flyweight moves outward,
pulling the arm of the control pin, so it pivots into the
‘‘run’’ position. The control pin no longer has any
effect on the exhaust valve and the engine operates at
full power.
Use an aerosol gasket remover, paint stripper, or
lacquer thinner to remove any old sealant. Apply the
solvent, allow time for it to work, and then brush the
surface with a brass wire brush. After the old sealant
is removed, clean the surface with isopropyl alcohol,
lacquer thinner, or aerosol electrical contact cleaner.
Do not scrape the surfaces, as any scratches, nicks, or
burrs can result in leaks. See Service Bulletin 252 for
further information.
Camshaft
Refer to A Guide to Engine Rebuilding (TP-2150-A)
for additional information. Measurement Guide
(TP-2159-B) and Engine Inspection Data Record
(TP-2435) are also available; use these to record
inspection results.
When the engine is stopped, the spring returns the
flyweight lever and control pin assembly to the
compression release position ready for the next start.
Inspection and Service
Check the lobes of the camshaft for wear or damage.
See Section 1 for minimum lift specifications. Inspect
the cam gear for badly worn, chipped or missing teeth.
Replacement of the camshaft will be necessary if any
of these conditions exist.
Crankshaft
Inspection and Service
Inspect the gear teeth of the crankshaft. If the teeth are
badly worn, chipped, or some are missing,
replacement of the crankshaft will be necessary.
Automatic Compression Release (ACR)
Some engines are equipped with the optional
Automatic Compression Release (ACR) mechanism.
The ACR lowers compression at cranking speeds to
make starting easier.
10.1
10
Section 10
Inspection and Reconditioning
Inspect the crankshaft bearing surfaces for scoring,
grooving, etc. Measure the running clearance between
the crankshaft journals and their respective bearing
bores. Use an inside micrometer or telescoping gauge
to measure the inside diameter of both bearing bores
in the vertical and horizontal planes. Use an outside
micrometer to measure the outside diameter of the
crankshaft main bearing journals. Subtract the journal
diameters from their respective bore diameters to get
the running clearances. Check the results against the
specifications in Section 1. If the running clearances
are within specification, and there is no evidence of
scoring, grooving, etc., no further reconditioning is
necessary. If the bearing surfaces are worn or
damaged, the crankcase and/or oil pan will need to be
replaced.
Inspect the crankshaft keyways. If worn or chipped,
replacement of the crankshaft will be necessary.
Inspect the crankpin for score marks or metallic
pickup. Slight score marks can be cleaned with crocus
cloth soaked in oil. If wear limits, as stated in
“Specifications and Tolerances” are exceeded, it will
be necessary to either replace the crankshaft or regrind
the crankpin to 0.25 mm (0.010 in.) undersize. If
reground, a 0.25 mm (0.010 in.) undersize connecting
rod (big end) must then be used to achieve proper
running clearance. Measure the crankpin for size,
taper, and out-of-round.
NOTE: If the crankpin is reground, visually check to
insure that the fillet blends smoothly with the
crankpin surface. See Figure 10-1.
High Point from
Fillet Intersections
The Fillet Must
Blend Smoothly
with the Bearing
Journal Surface
45°
Minimum
The connecting rod journal can be ground one size
under. When grinding the crankshaft, grinding stone
deposits can get caught in the oil passages, which
could cause severe engine damage. Removing the
crankpin plug when the crankshaft is ground provides
easy access for removing any grinding deposits that
may collect in the oil passages.
Use the following procedure to remove and replace
the plug.
Procedure to Remove Crankshaft Plug:
1. Drill a 3/16" hole through the plug in the
crankshaft.
2. Thread a 3/4" or 1" long self-tapping screw with a
flat washer into the drilled hole. The flat washer
must be large enough to seat against the shoulder
of the plug bore. See Figure 10-2.
3. Tighten the self-tapping screw until it draws the
plug out of the crankshaft.
Procedure to Install New Plug:
1. Use a single cylinder camshaft pin Part No.
47 380 09-S as a driver and tap the plug into the
plug bore until it seats at the bottom of the bore.
Make sure the plug is tapped in evenly to prevent
leakage.
Self-Tapping Screw
Flat Washer
12345678
12345678
12345678
12345678
12345678
Plug
Crankshaft
Figure 10-2. Removing Crankpin Plug.
This Fillet Area
Must Be Completely
Smooth
Figure 10-1. Crankpin Fillets.
10.2
Section 10
Inspection and Reconditioning
Crankcase
Inspection and Service
Check all gasket surfaces to make sure they are free of
gasket fragments. Gasket surfaces must also be free of
deep scratches or nicks.
Check the cylinder bore for scoring. In severe cases,
unburned fuel can cause scuffing and scoring of the
cylinder wall. It washes the necessary lubricating oils
off the piston and cylinder wall. As raw fuel seeps
down the cylinder wall, the piston rings make metal
to metal contact with the wall. Scoring of the cylinder
wall can also be caused by localized hot spots
resulting from blocked cooling fins or from
inadequate or contaminated lubrication.
If the cylinder bore is badly scored, excessively worn,
tapered, or out-of-round, resizing is necessary. Use an
inside micrometer to determine the amount of wear
(refer to “Specifications, Tolerances, and Special
Torque Values” in Section 1), then select the nearest
suitable oversize of either 0.25 mm (0.010 in.) or
0.50 mm (0.020 in.). Resizing to one of these oversizes
will allow usage of the available oversize piston and
ring assemblies. First, resize using a boring bar, then
use the following procedures for honing the cylinder.
NOTE: Some CV25 engines feature POWER-BORE™
cylinders, a special, patented nickel-silicone
plating process for increased power, superior
oil control, reduced exhaust emission, and
virtually permanent cylinder life. POWERBORE™ cylinders cannot be resized or honed
as described in the following procedure. If a
plated cylinder bore is damaged or out of
specification, use a new miniblock or short
block to repair the engine. Use the following
procedures for crankcases with a cast iron
sleeve.
Honing
While most commercially available cylinder hones can
be used with either portable drills or drill presses, the
use of a low speed drill press is preferred as it
facilitates more accurate alignment of the bore in
relation to the crankshaft crossbore. Honing is best
accomplished at a drill speed of about 250 RPM and
60 strokes per minute. After installing coarse stones in
hone, proceed as follows:
1. Lower hone into bore and after centering, adjust
so that the stones are in contact with the cylinder
wall. Use of a commercial cutting-cooling agent is
recommended.
2. With the lower edge of each stone positioned
even with the lowest edge of the bore, start drill
and honing process. Move the hone up and down
while resizing to prevent the formation of cutting
ridges. Check the size frequently.
NOTE: Kohler pistons are custom-machined to
exacting tolerances. When oversizing a
cylinder, it should be machined exactly
0.25 mm (0.010 in.) or 0.50 mm (0.020 in.)
over the new diameter (Section 1). The
corresponding oversize Kohler replacement
piston will then fit correctly.
3. When the bore is within 0.064 mm (0.0025 in.) of
the desired size, remove the coarse stones and
replace them with burnishing stones. Continue
with the burnishing stones until the bore is
within 0.013 mm (0.0005 in.) of the desired size
and then use finish stones (220-280 grit) and
polish the bore to its final size. A crosshatch
should be observed if honing is done correctly.
The crosshatch should intersect at approximately
23°-33° off the horizontal. Too flat an angle could
cause the rings to skip and wear excessively, and
too steep an angle will result in high oil
consumption. See Figure 10-3.
10
Figure 10-3. Cylinder Bore Crosshatch After
Honing.
10.3
Section 10
Inspection and Reconditioning
4. After resizing, check the bore for roundness,
taper, and size. Use an inside micrometer,
telescoping gauge, or bore gauge to take
measurements. The measurements should be
taken at three locations in the cylinder – at the
top, middle, and bottom. Two measurements
should be taken (perpendicular to each other) at
each of the three locations.
Clean Cylinder Bore After Honing
Proper cleaning of the cylinder walls following boring
and/or honing is very critical to a successful overhaul.
Machining grit left in the cylinder bore can destroy an
engine in less than one hour of operation after a
rebuild.
The final cleaning operation should always be a
thorough scrubbing with a brush and hot, soapy
water. Use a strong detergent that is capable of
breaking down the machining oil while maintaining a
good level of suds. If the suds break down during
cleaning, discard the dirty water and start again with
more hot water and detergent. Following the
scrubbing, rinse the cylinder with very hot, clear
water, dry it completely, and apply a light coating of
engine oil to prevent rusting.
6 mm (0.24 in.)
Measure 6 mm above the
Bottom of Piston Skirt at
Right Angles to Piston Pin
Figure 10-4. Measuring Piston Diameter.
2. Use an inside micrometer, telescoping gauge, or
bore gauge and measure the cylinder bore. Take
the measurement approximately 63.5 mm
(2.5 in.) below the top of the bore and
perpendicular to the piston pin.
3. Piston-to-bore clearance is the difference between
the bore diameter and the piston diameter (step 2
minus step 1).
Flywheel
Measuring Piston-to-Bore Clearance
Before installing the piston into the cylinder bore, it is
necessary that the clearance be accurately checked.
This step is often overlooked, and if the clearances are
not within specifications, engine failure will usually
result.
Inspection
Inspect the flywheel for cracks, and the flywheel
keyway for damage. Replace flywheel if it is cracked.
Replace the flywheel, the crankshaft, and the key if the
flywheel key is sheared or the keyway is damaged.
NOTE: Do not use a feeler gauge to measure pistonto-bore clearance–it will yield inaccurate
measurements. Always use a micrometer.
Inspect the ring gear for cracks or damage. Kohler
does not provide ring gears as a serviceable part.
Replace the flywheel if the ring gear is damaged.
Use the following procedure to accurately measure
the piston-to-bore clearance:
Cylinder Head and Valves
1. Use a micrometer and measure the diameter of
the piston 6 mm (0.24 in.) above the bottom of the
piston skirt and perpendicular to the piston pin.
See Figure 10-4.
10.4
Inspection and Service
After cleaning, check the flatness of the cylinder head
and the corresponding top surface of the crankcase,
using a surface plate or piece of glass and feeler gauge
as shown in Figure 10-5. The maximum allowable out
of flatness is 0.076 mm (0.003 in.).
Section 10
Inspection and Reconditioning
Carefully inspect the valve mechanism parts. Inspect
the valve springs and related hardware for excessive
wear or distortion. Check the valves and valve seat
area or inserts for evidence of deep pitting, cracks, or
distortion. Check clearance of the valve stems in the
guides. See Figure 10-6 for valve details and
specifications.
Figure 10-5. Checking Cylinder Head Flatness.
EXHAUST
VALVE
F
E
G
B
C
D
INTAKE VALVE
F
E
A
EXHAUST
INSERT
A
H
INTAKE
INSERT
G
H
D
B
A
10
Dimension
A
B
C
D
E
F
G
H
Seat Angle
Insert O.D.
Guide Depth
Guide I.D.
Valve Head Diameter
Valve Face Angle
Valve Margin (Min.)
Valve Stem Diameter
Intake
Exhaust
89°
36.987/37.013 mm (1.4562/1.4572 in.)
4 mm (0.1575 in.)
7.038/7.058 mm (0.2771/0.2779 in.)
33.37/33.63 mm (1.3138/1.3240 in.)
45°
1.5 mm (0.0591 in.)
6.982/7.000 mm (0.2749/0.2756 in.)
89°
32.987/33.013 mm (1.2987/1.2997 in.)
6.5 mm (0.2559 in.)
7.038/7.058 mm (0.2771/0.2779 in.)
29.37/29.63 mm (1.1563/1.1665 in.)
45°
1.5 mm (0.0591 in.)
6.970/6.988 mm (0.2744/0.2751 in.)
Figure 10-6. Valve Details.
Hard starting, or loss of power accompanied by high
fuel consumption may be symptoms of faulty valves.
Although these symptoms could also be attributed to
worn rings, remove and check the valves first. After
removal, clean the valve heads, faces, and stems with a
power wire brush. Then, carefully inspect each valve
for defects such as warped head, excessive corrosion,
or worn stem end. Replace valves found to be in bad
condition. A normal valve and valves in bad condition
are shown in the accompanying illustrations.
10.5
Section 10
Inspection and Reconditioning
Normal: Even after long hours of operation a valve
can be reconditioned and reused if the face and
margin are in good shape. If a valve is worn to where
the margin is less than 1/32" do not reuse it. The valve
shown was in operation for almost 1000 hours under
controlled test conditions.
Leakage: A poor grind on face or seat of valve will
allow leakage resulting in a burned valve on one side
only.
Coking: Coking is normal on intake valves and is not
harmful. If the seat is good, the valve could be reused
after cleaning.
Bad Condition: The valve depicted here should be
replaced. Note the warped head; margin damaged and
too narrow. These conditions could be attributed to
excessive hours or a combination of poor operating
conditions.
10.6
Section 10
Inspection and Reconditioning
Excessive Combustion Temperatures: The white
deposits seen here indicate very high combustion
temperatures, usually due to a lean fuel mixture.
Gum: Gum deposits usually result from using stale
gasoline. Gum is a prevalent cause of valve sticking.
The cure is to ream the valve guides and clean or
replace the valves, depending on their condition.
Stem Corrosion: Moisture in fuel or from
condensation are the most common causes of valve
stem corrosion. Condensation occurs from improper
preservation during storage and when engine is
repeatedly stopped before it has a chance to reach
normal operating temperatures. Replace corroded
valves.
Overheating: An exhaust valve subject to overheating
will have a dark discoloration in the area above the
valve guide. Worn guides and faulty valve springs
may cause this condition. Also check for clogged air
intake, and blocked fins when this condition is noted.
10.7
10
Section 10
Inspection and Reconditioning
Valve Guides
If a valve guide is worn beyond specifications, it will
not guide the valve in a straight line. This may result
in burnt valve faces or seats, loss of compression, and
excessive oil consumption.
To check valve guide-to-valve stem clearance,
thoroughly clean the valve guide and, using a splitball gauge, measure the inside diameter of the guide.
Then, using an outside micrometer, measure the
diameter of the valve stem at several points on the
stem where it moves in the valve guide. Use the
largest stem diameter to calculate the clearance by
subtracting the stem diameter from the guide
diameter. If the intake clearance exceeds
0.038/0.076 mm (0.0015/0.0030p in.) or the exhaust
clearance exceeds 0.050/0.088 mm (0.0020/0.0035 in.),
determine whether the valve stem or guide is
responsible for the excessive clearance.
The maximum (I.D.) wear on the intake valve guide is
7.134 mm (0.2809 in.) while 7.159 mm (0.2819 in.) is
the maximum allowed on the exhaust guide. The
guides are not removable but can be reamed 0.25 mm
(0.010 in.) oversize. Valves with 0.25 mm oversize
stems must then be used.
If the guides are within limits but the valve stems are
worn beyond limits, install new valves.
Valve Seat Inserts
Hardened steel alloy intake and exhaust valve seat
inserts are press-fitted into the cylinder head. The
inserts are not replaceable but can be reconditioned if
not too badly pitted or distorted. If cracked or badly
warped, the cylinder head should be replaced.
Recondition the valve seat inserts following the
instructions provided with the valve seat cutter being
used. A typical cutter is shown in Figure 10-7. The
final cut should be made with an 89° cutter as
specified for the valve seat angle in Figure 10-6.
Cutting the proper 45° valve face angle, as specified in
Figure 10-6, and the proper valve seat angle (44.5°,
half of the full 89° angle), will achieve the desired 0.5°
(1.0° full cut) interference angle where the maximum
pressure occurs on the outside diameters of the valve
face and seat.
10.8
Valve Seat
Cutter
Pilot
Figure 10-7. Typical Valve Seat Cutter.
Lapping Valves
Reground or new valves must be lapped in, to provide
proper fit. Use a hand valve grinder with a suction
cup for final lapping. Lightly coat the valve face with a
“fine” grade of grinding compound, then rotate the
valve on its seat with the grinder. Continue grinding
until a smooth surface is obtained on the seat and on
the valve face. Thoroughly clean the cylinder head in
soap and hot water to remove all traces of grinding
compound. After drying the cylinder head, apply a
light coating of SAE 10 oil to prevent rusting.
Intake Valve Stem Seal
These engines use valve stem seals on the intake
valves. Always use a new seal when the valves are
removed from the cylinder head. The seals should also
be replaced if deteriorated or damaged in any way.
Never reuse an old seal.
Pistons and Rings
Inspection
Scuffing and scoring of pistons and cylinder walls
occurs when internal engine temperatures approach
the welding point of the piston. Temperatures high
enough to do this are created by friction, which is
usually attributed to improper lubrication and/or
overheating of the engine.
Normally, very little wear takes place in the piston
boss-piston pin area. If the original piston and
connecting rod can be reused after new rings are
installed, the original pin can also be reused but new
piston pin retainers are required. The piston pin is
included as part of the piston assembly – if the pin
boss in the piston or the pin are worn or damaged, a
new piston assembly is required.
Section 10
Inspection and Reconditioning
Ring failure is usually indicated by excessive oil
consumption and blue exhaust smoke. When rings
fail, oil is allowed to enter the combustion chamber
where it is burned along with the fuel. High oil
consumption can also occur when the piston ring end
gap is incorrect because the ring cannot properly
conform to the cylinder wall under this condition. Oil
control is also lost when ring gaps are not staggered
during installation.
Detonation damage occurs when a portion of the fuel
charge ignites spontaneously from heat and pressure
shortly after ignition. This creates two flame fronts,
which meet and explode to create extreme hammering
pressures on a specific area of the piston. Detonation
generally occurs from using low octane fuels.
When cylinder temperatures get too high, lacquer and
varnish collect on pistons causing rings to stick, which
results in rapid wear. A worn ring usually takes on a
shiny or bright appearance.
Preignition or ignition of the fuel charge before the
timed spark can cause damage similar to detonation.
Preignition damage is often more severe than
detonation damage. Preignition is caused by a hot
spot in the combustion chamber from sources such as
glowing carbon deposits, blocked cooling fins, an
improperly seated valve, or wrong spark plug(s).
Scratches on rings and pistons are caused by abrasive
material such as carbon, dirt, or pieces of hard metal.
See Figure 10-8 for some common types of piston and
ring damage.
Stuck, Broken Rings
Abrasive Scratched Rings
10
Overheated or Deteriorated Oil
Scored Piston and Rings
Figure 10-8. Common Types of Piston Damage.
10.9
Section 10
Inspection and Reconditioning
Replacement pistons are available in STD bore size,
and 0.25 mm (0.010 in.), and 0.50 mm (0.020 in.)
oversize. Replacement pistons include new piston ring
sets and new piston pins.
Replacement ring sets are also available separately for
STD, 0.25 mm (0.010 in.), and 0.50 mm (0.020 in.)
oversize pistons. Always use new piston rings when
installing pistons. Never use old rings.
Some important points to remember when servicing
piston rings:
1. The cylinder bore must be deglazed before
service ring sets are used.
2. If the cylinder bore does not need reboring and if
the old piston is within wear limits and free of
score or scuff marks, the old piston may be
reused.
3. Remove the old rings and clean up the grooves.
Never reuse old rings.
4. Before installing the new rings on the piston,
place the top two rings, each in turn, in its
running area in the cylinder bore and check the
end gap. See Figure 10-9. Compare the ring gap
to the specifications listed in Section 1.
Figure 10-10. Measuring Piston Ring Side
Clearance.
Install New Piston Rings
To install new piston rings, proceed as follows:
NOTE: Rings must be installed correctly. Ring
installation instructions are usually included
with new ring sets. Follow instructions
carefully. Use a piston ring expander to
install rings. See Figure 10-11. Install the
bottom (oil control) ring first and the top
compression ring last. Refer to Figure 10-12.
Piston Ring
Piston Ring
Expander
Figure 10-11. Installing Piston Rings.
Figure 10-9. Measuring Piston Ring End Gap.
5. After installing the new compression (top and
middle) rings on the piston, check the piston-toring side clearance. Compare the clearance to
specifications listed in Section 1. If the side
clearance is greater than specified, a new piston
must be used. Refer to Figure 10-10.
10.10
Section 10
Inspection and Reconditioning
Piston Ring
Dykem
Stripe
End Gap
Identification
Mark
Service replacement connecting rods are available in
STD crankpin size and 0.25 mm (0.010 in.) undersize.
The 0.25 mm (0.010 in.) undersized rods have an
identification marking on the lower end of the rod
shank. Always refer to the appropriate parts
information to ensure that correct replacements are
used.
Hydraulic Lifters
Piston
Top
Compression
Ring
Center
Compression
Ring
Rails
Oil Control Ring
(Three-piece)
Expander
Inspection
Check the base surface of the hydraulic lifters for wear
or damage. If the lifters need to be replaced, apply a
liberal coating of Kohler lubricant (see Section 2) to
the base of each new lifter before it is installed.
“Bleeding” the Lifters
To prevent a possible bent push rod or broken rocker
arm, it is important to “bleed” any excess oil out of
the lifters before they are installed.
1. Cut a 50-75 mm (2-3 in.) piece from the end of an
old push rod and chuck it in a drill press.
2. Lay a rag or shop towel on the table of the drill
press and place the lifter, open end up, on the
towel.
Figure 10-12. Piston Ring Installation.
1. Oil Control Ring (Bottom Groove): Install the
expander and then the rails. Make sure the ends
of the expander are not overlapped.
2. Middle Compression Ring (Center Groove):
Install the center ring using a piston ring
expander tool. Make sure the “identification”
mark is up or the dykem stripe (if contained) is to
the left of the end gap.
3. Top Compression Ring (Top Groove): Install the
top ring using a piston ring expander. Make sure
the “identification” mark is up or the dykem
stripe (if contained), is to the left of the end gap.
Connecting Rods
Offset, stepped-cap connecting rods are used in all
these engines.
Inspection and Service
Check the bearing area (big end) for excessive wear,
score marks, running and side clearances (refer to
Section 1, “Specifications, Tolerances, and Special
Torque Values”). Replace the rod and cap if scored or
excessively worn.
3. Lower the chucked push rod until it contacts the
plunger in the lifter. Slowly “pump” the plunger
two or three times to force the oil out of the feed
hole in the side of the lifter.
Oil Pan Assembly
Inspection
Inspect the oil seal in the oil pan and remove it if it is
worn or damaged. Refer to ‘‘Install Oil Seal in Oil
Pan’’ in Section 11 for new oil seal installation.
Inspect the main bearing surface for wear or damage
(refer to Section 1, “Specifications, Tolerances, and
Special Torque Values”). Replace the oil pan assembly
if required.
Governor Gear Assembly
Inspection
Inspect the governor gear teeth. Replace the gear if it
is worn, chipped, or if any teeth are missing. Inspect
the governor weights. They should move freely in the
governor gear.
10.11
10
Section 10
Inspection and Reconditioning
Disassembly
The governor gear must be replaced once it is
removed from the oil pan.
NOTE: The governor gear is held onto the shaft by
small molded tabs in the gear. When the gear
is removed from the shaft, these tabs are
destroyed and the gear must be replaced.
Therefore, remove the gear only if absolutely
necessary.
1. Remove the regulating pin and governor gear
assembly. See Figure 10-13.
Reassembly
1. Install the locking tab thrust washer on the
governor gear shaft with the tab down.
2. Position the regulating pin within the governor
gear/flyweight assembly and slide both onto
governor shaft.
Oil Pump Assembly
Disassembly
1. Remove the two hex flange screws.
2. Remove the oil pump assembly from the oil pan.
Mounting Screws
Relief
Valve
Pickup
Figure 10-13. Removing Governor Gear.
Figure 10-15. Removing Oil Pump.
2. Remove the locking tab thrust washer located
under the governor gear assembly.
3. Carefully inspect the governor gear shaft and
replace it only if it is damaged. After removing
the damaged shaft, press or lightly tap the
replacement shaft into the oil pan to the depth
shown in Figure 10-14.
Gear Shaft
34.0 mm (1.3386 in.)
33.5 mm (1.3189 in.)
19.40 mm (0.7638 in.)
Figure 10-14. Governor Shaft Press Depth.
10.12
3. Remove the oil pump rotor. If a plastic pickup is
used (See Figures 10-15 and 10-17), unhook the
locking clip, and carefully pull it free from the oil
pump housing.
4. If the relief valve is like that shown in Figure
10-16, drive out the pin to remove the oil pressure
relief valve piston and spring. Refer to the
following inspection and reassembly procedures.
If the relief valve is a one-piece style, staked to
the oil pump housing (See Figures 10-15 and
10-17), removal should not be attempted, nor is
internal servicing possible. If a problem with the
relief valve is encountered, the oil pump should
be replaced.
Section 10
Inspection and Reconditioning
Piston
Spring
Figure 10-16. Oil Pump, Oil Pickup, and Relief
Valve (Original Style).
Roll Pin
Figure 10-18. Oil Pressure Relief Valve Piston and
Spring.
Reassembly
1. Install the pressure relief valve piston and spring.
2. Install the oil pickup to the oil pump body.
Lubricate the O-Ring with oil and make sure it
remains in the groove as the pickup is being
installed.
3. Install the rotor.
4. Install the oil pump body to the oil pan and
secure with the two hex flange screws. Torque the
hex flange screws as follows:
Figure 10-17. Oil Pump, Plastic Oil Pickup, and
One-Piece Relief Valve (Later Style).
a. Install fastener into location No. 1 and lightly
tighten to position pump.
Inspection
Inspect the oil pump housing, gear, and rotors for
nicks, burrs, wear, or any visible damage. If any parts
are worn or damaged, replace the oil pump.
b. Install fastener into location No. 2 and fully
torque to the recommended value.
Inspect the oil pressure relief valve piston. It should be
free of nicks or burrs.
c. Torque fastener in location No. 1 to the
recommended value.
Check the spring for wear or distortion. The free
length of the spring should be approximately 47.4 mm
(1.8 in.). Replace the spring if it is distorted or worn.
See Figure 10-18.
Oil Pump Torque Sequence
First Time Installation:
All Reinstallations:
10.7 N·m (95 in. lb.)
6.7 N·m (60 in. lb.)
10.13
10
Section 10
Inspection and Reconditioning
5. After torquing, rotate the gear and check for
freedom of movement. Make sure there is no
binding. If binding occurs, loosen the screws,
reposition the pump, retorque the hex flange
screws and recheck the movement.
Crankcase Breather System
The breather system is designed to control the amount
of oil in the head area and still maintain the necessary
vacuum in the crankcase.
Figure 10-20. Oil Separator.
Governor Cross Shaft Oil Seal
If the governor cross shaft seal is damaged and/or
leaks, replace it using the following procedure.
Remove the oil seal from the crankcase and replace it
with a new one. Install the new seal to the depth
shown in Figure 10-21 using a seal installer.
Figure 10-19. Crankcase with Breather Reed.
A spring steel reed and stop is mounted on each bank
of the crankcase, between the lifter bores. See Figure
10-19. When the pistons move downward, air is
pushed past the reeds into the cylinder head cavities.
On the #2 cylinder, the upper end of the head is
completely sealed by the rocker cover, so a low,
positive pressure is created in the head cavity. The #1
rocker cover has a hole in it for venting. The bottom
nipple of an oil separator canister is fitted into the
hole with a grommet. From the top nipple of the
canister, a breather hose goes back to the air cleaner
base. The air moving into the #1 head cavity is filtered
through the oil separator and then is drawn into the
air intake. See Figure 10-20.
The upward travel of the pistons closes the reeds and
creates a low vacuum in the lower crankcase. The
combination of low pressure above and low vacuum
below forces any accumulated oil out of the #2 head
area into the crankcase. On the #1 bank you have
atmospheric pressure above and vacuum below, again
drawing any oil toward the crankcase.
10.14
2.0 mm (0.0787 in.)
Governor Cross
Shaft Seal
Figure 10-21. Installing Cross Shaft Oil Seal.
Section 11
Reassembly
Section 11
Reassembly
General
NOTE: Make sure the engine is assembled using all
specified torque values, tightening sequences,
and clearances. Failure to observe
specifications could cause severe engine wear
or damage. Always use new gaskets. Apply a
small amount of oil to the threads of critical
fasteners before assembly, unless a Sealant or
Loctite® is specified or pre-applied.
Make sure all traces of any cleaner are removed before
the engine is assembled and placed into operation.
Even small amounts of these cleaners can quickly
break down the lubricating properties of engine oil.
Check the oil pan, crankcase, cylinder heads, and
valve covers to be certain that all old sealing material
has been removed. Use gasket remover, lacquer
thinner, or paint remover to remove any remaining
traces. Clean the surfaces with isopropyl alcohol,
acetone, lacquer thinner, or electrical contact cleaner.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
Install blower housing and outer baffles.
Install Oil SentryTM.
Install control panel.
Install valve covers.
Install carburetor.
Install external governor controls.
Install throttle and choke controls.
Install electric starter motor.
Install fuel pump.
Install air cleaner assembly (see Section 4).
Install muffler.
Install oil cooler.
Install oil filter and fill crankcase with oil.
Connect spark plug leads.
Install Flywheel End Oil Seal
1. Make sure that the seal bore of the crankcase is
clean and free of any nicks or burrs. See Figure
11-1.
Typical Reassembly Sequence
The following sequence is suggested for complete
engine reassembly. This procedure assumes that all
components are new or have been reconditioned, and
all component subassembly work has been completed.
The sequence may vary to accommodate options or
special equipment. Detailed procedures follow:
1. Install flywheel end oil seal.
2. Install governor cross shaft.
3. Install crankshaft.
4. Install connecting rods with pistons and rings.
5. Install camshaft.
6. Install oil pan assembly.
7. Install stator and backing plates.
8. Install flywheel.
9. Install fan and grass screen.
10. Install hydraulic lifters.
11. Install cylinder heads.
12. Install push rods and rocker arms.
13. Install ignition modules.
14. Install intake manifold.
15. Install breather cover and inner baffles.
11
Figure 11-1. Seal Bore of Crankcase.
2. Apply a light coat of engine oil to the outside
diameter of the oil seal.
3. Drive the oil seal into the crankcase using a seal
driver. Make sure the oil seal is installed straight
and true in the bore and the tool bottoms against
the crankcase. See Figure 11-2.
11.1
Section 11
Reassembly
Figure 11-2. Installing Oil Seal in Crankcase.
Figure 11-4. Installing Governor Cross Shaft Hitch
Pin (6 mm Shaft).
Install Governor Cross Shaft
1. Lubricate the governor cross shaft bearing
surfaces in the crankcase with engine oil.
2. Slide the small lower washer onto the governor
cross shaft and install the cross shaft from the
inside of the crankcase.
3. 6 mm Governor Shaft: Install the plain washer
and then insert the hitch pin into the smaller,
lower hole of the governor cross shaft. See
Figures 11-3 and 11-4.
8 mm Governor Shaft: Install the nylon washer
onto the governor cross shaft, then start the pushon retaining ring. Hold the cross shaft up in
position, place a 0.50 mm (0.020 in.) feeler gauge
on top of the nylon washer, and push the
retaining ring down the shaft to secure. Remove
the feeler gauge, which will have established the
proper end play. See Figures 11-5 and 11-6.
Figure 11-5. Installing 8 mm Governor Cross Shaft.
Figure 11-6. Setting Governor Cross Shaft End
Play (8 mm Shaft).
Figure 11-3. Installing 6 mm Governor Cross Shaft.
11.2
Section 11
Reassembly
Install Crankshaft
1. Carefully slide the flywheel end of the crankshaft
through the main bearing in the crankcase. See
Figure 11-7.
1. Stagger the piston rings in the grooves until the
end gaps are 120° apart. The oil ring rails should
also be staggered.
2. Lubricate the cylinder bore, piston, and piston
rings with engine oil. Compress the rings using a
piston ring compressor.
3. Lubricate the crankshaft journals and connecting
rod bearing surfaces with engine oil.
4. Make sure the ‘‘Fly’’ stamping on the piston is
facing towards the flywheel side of the engine.
Use a hammer with a rubber grip and gently tap
the piston into the cylinder as shown in Figure
11-9. Be careful that the oil ring rails do not
spring free between the bottom of the ring
compressor and the top of the cylinder.
Figure 11-7. Installing Crankshaft.
Install Connecting Rods with Pistons and
Rings
NOTE: The cylinders are numbered on the crankcase.
Make sure to install the piston, connecting
rod, and end cap into its appropriate cylinder
bore as previously marked at disassembly.
Do not mix the end caps and connecting
rods.
NOTE: Proper orientation of the piston/connecting
rod assemblies inside the engine is extremely
important. Improper orientation can cause
extensive wear or damage. Be certain the
pistons and connecting rods are assembled
exactly as shown in Figure 11-8.
Cylinder #2
Cylinder #1
Figure 11-8. Proper Piston Connecting Rod
Orientation.
Figure 11-9. Installing Piston Assembly Using Ring
Compressor Tool.
5. Install the inner rod cap to the connecting rod
using the two hex flange screws. Three different
types of connecting rod bolts have been used, and
each has a different torque value. If 8 mm straight
shank type bolts are used, torque in increments to
22.7 N·m (200 in. lb.). If 8 mm step-down bolts
are used, torque in increments to 14.7 N·m
(130 in. lb.). If 6 mm straight shank bolts are
used, torque in increments to 11.3 N·m
(100 in. lb.). Illustrated instructions are provided
in the service rod package. See Figures 11-10 and
11-11.
NOTE: Align the chamfer of the connecting rod
with the chamfer of its mating end cap.
When installed, the flat faces of the
connecting rods should face each other.
The faces with the raised rib should be
toward the outside.
11.3
11
Section 11
Reassembly
Torque these to 22.7 N·m (200 in. lb.)
8 mm Straight Shank
Torque these to 14.7 N·m (130 in. lb.)
8 mm Step-Down
Torque these to 11.3 N·m (100 in. lb.)
6 mm Straight Shank
Figure 11-12. Apply Camshaft Lubricant to Cam
Lobes.
2. Position the timing mark of the crankshaft gear at
the 12 o’clock position.
Figure 11-10. Connecting Rod Bolts.
3. Turn the governor cross shaft clockwise until the
lower end of the shaft contacts the cylinder. Make
sure the cross shaft remains in this position while
installing the camshaft. See Figure 11-13.
4. Slide the camshaft into the bearing surface of the
crankcase, positioning the timing mark of
camshaft gear at the 6 o’clock position. Make sure
the camshaft gear and crankshaft gear mesh with
both timing marks aligned. See Figure 11-13.
Governor
Cross Shaft
Figure 11-11. Torquing Connecting Rod End Cap.
6. Repeat the above procedure for the other
connecting rod and piston assembly.
Timing
Marks
Install Camshaft
1. Liberally apply camshaft lubricant (see Section 2)
to each of the cam lobes. Lubricate the camshaft
bearing surfaces of the crankcase and camshaft
with engine oil. See Figure 11-12.
11.4
Figure 11-13. Aligning Crankshaft and Camshaft
Timing Marks.
Section 11
Reassembly
Governor Gear Assembly
Determining Camshaft End Play
1. Install the shim removed during disassembly
onto the camshaft.
2. Position the camshaft end play checking tool on
the camshaft. See Figure 11-14.
The governor gear assembly is located inside the oil
pan. If service was required, and the governor was
removed, refer to the assembly procedures under
‘‘Governor Gear Assembly’’ in Section 10.
Install Oil Seal in Oil Pan
1. Check to make sure that there are no nicks or
burrs in the crankshaft bore of the oil pan.
2. Apply a light coat of engine oil to the outside
diameter of the oil seal.
3. Drive the oil seal into the oil pan using a seal
driver. Make sure the oil seal is installed straight
and true in the bore, to the depth shown in
Figures 11-15 and 11-16.
Figure 11-14. Checking Camshaft End Play.
3. Apply pressure on the camshaft end play
checking tool (pushing camshaft toward
crankshaft). Use a feeler gauge to measure the
camshaft end play between the shim spacer and
the checking tool. Camshaft end play should be
0.076/0.127 mm (0.003/0.005 in.).
4. If the camshaft end play is not within the
specified range, remove the checking tool and
replace the shim as necessary.
Figure 11-15. Installing Oil Seal in Oil Pan.
Several color-coded shims are available.
White: 0.69215/0.73025
Blue: 0.74295/0.78105
Red:
0.79375/0.83185
Yellow: 0.84455/0.88265
Green: 0.89535/0.99345
Gray: 0.94615/0.98425
Black: 0.99695/1.03505
mm
mm
mm
mm
mm
mm
mm
(0.02725/0.02875
(0.02925/0.03075
(0.03125/0.03275
(0.03325/0.03475
(0.03525/0.03675
(0.03725/0.03875
(0.03925/0.04075
in.)
in.)
in.)
in.)
in.)
in.)
in.)
6.5 mm
(0.255 in.)
11
Oil Seal
5. Reinstall the end play checking tool and recheck
the end play.
Oil Pump Assembly
The oil pump is mounted inside the oil pan. If service
was required, and the oil pump was removed, refer to
the assembly procedures under ‘‘Oil Pump Assembly’’
in Section 10.
Figure 11-16. Oil Seal Depth in Oil Pan.
11.5
Section 11
Reassembly
Install Oil Pan Assembly
RTV sealant is used as a gasket between the oil pan
and the crankcase on CV17-23 engines. CV25-750
engines use an oil pan gasket. Refer to Section 2 for a
listing of approved sealants. Always use fresh sealant.
Using outdated sealant can result in leakage.
6. Install the ten hex flange screws securing the oil
pan to the crankcase. Torque the fasteners in the
sequence shown in Figure 11-18 to 24.4 N·m
(216 in. lb). On some engines one of the ten
mounting screws is plated. The plated screw is
typically installed in the #6 hole shown in Figure
11-18.
1. Be sure the sealing surfaces have been cleaned
and prepared as described at the beginning of
Section 10 or in Service Bulletin 252.
2. Check to make sure that there are no nicks or
burrs on the sealing surfaces of the oil pan or
crankcase.
3. Apply a 1.5 mm (1/16 in.) bead of sealant to the
sealing surface of the oil pan on CV17-23 engines.
See Figure 11-17 for the sealant pattern. On
CV25-750 engines use a new gasket. Before
installing the gasket, check the dowel pin on the
oil filter side of the crankcase. If a “split” style
dowel pin is contained, replace it with a closed
seam style pin provided with the new gasket.
3
1
10
5
8
7
6
9
4
2
Figure 11-18. Oil Pan Fastener Torque Sequence.
Apply 1.5 mm (1/16 in.)
bead of sealant.
RTV must be
all around
O-Ring
groove
Point "B"
Figure 11-19. Torquing Oil Pan Fasteners.
Point "A"
Install Stator and Backing Plates
Fill groove between points "A" and "B" with RTV.
Figure 11-17. Oil Pan Sealant Pattern CV17-23.
4. Make sure the end of the governor cross shaft is
lying against the bottom of cylinder 1 inside the
crankcase. See Figure 11-13.
5. Install the oil pan to the crankcase. Carefully seat
the camshaft and the crankshaft into their mating
bearings. Rotate the crankshaft slightly to help
engage the oil pump and governor gear meshes.
11.6
1. Apply pipe sealant with Teflon® (Loctite® No.
59241 or equivalent) to the stator mounting holes.
2. Position the stator aligning the mounting holes so
that the leads are at the bottom, towards the
crankcase.
3. Install and torque the two hex flange screws to
6.2 N·m (55 in. lb.). See Figure 11-20.
Section 11
Reassembly
Install Flywheel
WARNING: Damaging Crankshaft and
Flywheel Can Cause Personal Injury!
Using improper procedures to install the flywheel can crack
or damage the crankshaft and/or flywheel. This not only
causes extensive engine damage, but can also cause personal
injury, since broken fragments could be thrown from the
engine. Always observe and use the following precautions
and procedures when installing the flywheel.
Figure 11-20. Torquing Stator Screws.
4. Route the stator leads in the crankcase channel,
then install the backing plates and stator wire
bracket (if used). Secure with the four hex flange
screws. See Figures 11-21 and 11-22. Torque the
screws to 7.3 N·m (65 in. lb.).
NOTE: Before installing the flywheel, make sure the
crankshaft taper and flywheel hub are clean,
dry, and completely free of any lubricants.
The presence of lubricants can cause the
flywheel to be over stressed and damaged
when the hex flange screw is torqued to
specifications.
Figure 11-23. Clean and Dry Taper of Crankshaft.
Figure 11-21. Route Stator Leads in Groove.
11
Figure 11-24. Carefully Align Keyway to Key.
Figure 11-22. Installing Backing Plates and Stator
Wire Bracket.
1. Install the woodruff key into the keyway of the
crankshaft. Make sure that the key is properly
seated and parallel with the shaft taper.
11.7
Section 11
Reassembly
NOTE: Make sure the flywheel key is installed
properly in the keyway. The flywheel
can become cracked or damaged if the
key is not properly installed.
2. Install the flywheel onto the crankshaft being
careful not to shift the woodruff key. See Figure
11-24.
3. Install the hex flange screw and washer.
4. Use a flywheel strap wrench or holding tool to
hold the flywheel. Torque the hex flange screw
securing the flywheel to the crankshaft to
66.4 N·m (49 ft. lb.). See Figure 11-25.
Figure 11-26. Installing Fan.
3. If the engine has a plastic grass screen, snap the
screen onto the fan. See Figure 11-27. Due to the
possibility of damaging the posts during removal,
install the retainers on different posts from which
they were removed. Start the retainers by hand,
then push them down with a 13 mm (1/2”) socket
until they lock. If the engine has a metal screen, it
will be installed later.
Figure 11-25. Installing and Torquing Flywheel
Fastener.
Install Fan and Grass Screen
1. Install the fan onto the flywheel using the four
hex flange screws (engines with plastic grass
screen).
NOTE: Position the locating tabs on the back of the
fan in the recesses of the flywheel. See Figure
11-26.
2. Torque the screws to 9.9 N·m (88 in. lb.).
Figure 11-27. Installing Plastic Grass Screen.
Install Supports for the Metal Grass
Screen
1. If a metal grass screen is used, with threaded
individual supports, install a spacer washer on
the external threads. Apply blue Loctite® No 242
(removable) to the threads. Install the four
supports as shown in Figure 11-28.
11.8
Section 11
Reassembly
Figure 11-28. Installing Supports for Metal Grass
Screen.
2. Tighten the supports with a torque wrench to
9.9 N·m (99 in. lb.). See Figure 11-29. The grass
screen will be installed to the supports after the
blower housing is in place.
Figure 11-30. Applying Camshaft Lubricant to
Bottom of Lifters.
3. Note the mark or tag identifying the hydraulic
lifters as either intake or exhaust and cylinder 1
or cylinder 2. Install the hydraulic lifters into
their appropriate locations in the crankcase. Do
not use a magnet. See Figure 11-31.
NOTE: Hydraulic lifters should always be
installed in the same position as before
disassembly. The exhaust lifters are
located on the output shaft (oil pan) side
of the engine while the intake lifters are
located on the fan side of the engine. The
cylinder numbers are embossed on the
top of the crankcase and each cylinder
head. See Figure 11-32.
Figure 11-29. Torquing Supports for Metal Screen
(Some Models).
11
Install Hydraulic Lifters
1. See “Servicing Hydraulic Lifters” in Section 10
for lifter preparation (bleed down) procedures.
2. Apply camshaft lubricant (see Section 2) to the
bottom surface of each lifter. See Figure 11-30.
Lubricate the hydraulic lifters and the lifter bores
in the crankcase with engine oil.
Figure 11-31. Installing Hydraulic Lifters.
11.9
Section 11
Reassembly
Intake Valve Seal
Figure 11-32. Match Numbers on Cylinder Barrel
and Head.
Figure 11-34. Intake Valve Seal Location.
Assemble Cylinder Heads
4. If the breather reeds and stops were removed
from the crankcase, reinstall them at this time
and secure with the hex flange screw. Torque the
screw to 4.0 N·m (35 in. lb.). See Figure 11-33.
Prior to installation, lubricate all components with
engine oil, paying particular attention to the lip of the
valve stem seal, valve stems, and valve guides. Install
the following items in the order listed below using a
valve spring compressor. See Figures 11-35 and 11-36.
•
•
•
•
•
Intake and exhaust valves
Valve spring caps
Valve springs
Valve spring retainers
Valve spring keepers
Valve
Keepers
Figure 11-33. Installed Breather Reed.
Valve Stem Seals
These engines use valve stem seals on the intake
valves and occasionally on the exhaust valves. Use a
new seal whenever the valve is removed or if the seal
is deteriorated or damaged in any way. Never reuse an
old seal. See Figure 11-34.
11.10
Retainer
Spring
Figure 11-35. Valve Components.
Cap
Section 11
Reassembly
Figure 11-36. Installing Valves with Valve Spring
Compressor.
Install Cylinder Heads
NOTE: Cylinder heads must be attached with the
original type of mounting hardware, using
either hex flange screws, or mounting studs
with nuts and washers. The heads are
machined differently for studs than for
screws, so the fastening method cannot be
altered unless the heads are being replaced.
Do not intermix the components.
Figure 11-37. Torquing Cylinder Head Fasteners.
4. Torque the hex flange screws in two stages; first
to 22.6 N·m (200 in. lb.), then finally to 41.8 N·m
(370 in. lb.), following the sequence in Figure
11-38.
1. Check to make sure there are no nicks or burrs on
the sealing surfaces of the cylinder head or the
crankcase.
Heads secured with hex flange screws:
2. Install a new cylinder head gasket (with printing
up).
NOTE: Match the numbers embossed on the
cylinder heads and crankcase. See Figure
11-32.
3. Install the cylinder head and start the four new
hex flange screws.
NOTE: When installing cylinder heads, new
screws should always be used.
#1
#2
Figure 11-38. Cylinder Head Fastener Torque
Sequence.
Heads secured with mounting studs, nuts, and
washers:
2. If all of the studs were left intact, go to Step 6. If
any studs were disturbed or removed, install new
studs as described in Step 3. Do not use/reinstall
any loosened or removed studs.
3. Install new mounting stud(s) into the crankcase.
a. Thread and lock two of the mounting nuts
together on the smaller diameter threads.
11.11
11
Section 11
Reassembly
b. Thread the opposite end of the stud, with the
preapplied locking compound, into the
crankcase, until the specified height from the
crankcase surface is achieved. See Figure
11-39. When threading in the studs, use a
steady tightening motion without interruption
until the proper height is obtained. Otherwise
the frictional heat from the engaging threads
may cause the locking compound to set up
prematurely.
The studs closest to the lifters must have an exposed
height of 75 mm (2 15/16 in.).
The studs furthest from the lifters must have an
exposed height of 68 mm (2 3/4 in.).
c. Remove the nuts and repeat the procedure as
required.
Figure 11-40. Torquing the Cylinder Head Mounting
Nuts (Stud Design).
Install Push Rods and Rocker Arms
NOTE: Push rods should always be installed in the
same position as before disassembly.
1. Note the mark or tag identifying the push rod as
either intake or exhaust and cylinder #1 or #2. Dip
the ends of the push rods in engine oil and install,
making sure that each push rod ball seats in its
hydraulic lifter socket. See Figure 11-41.
Figure 11-39. Installing New Mounting Studs to
Specified Height.
4. Check that the dowel pins are in place and install
a new cylinder head gasket (printing up).
5. Install the cylinder head. Match the numbers on
the cylinder heads and the crankcase. See Figure
11-32. Make sure the head is flat on the gasket
and dowel pins.
6. Lightly lubricate the exposed (upper) threads of
the studs with engine oil. Install a flat washer and
hex nut onto each of the mounting studs. Torque
the hex nuts in two stages; first to 16.9 N·m
(150 in. lb.), then finally to 33.9 N·m (300 in. lb.),
following the sequence in Figure 11-38.
11.12
Figure 11-41. Install Push Rods in Their Original
Position.
2. Apply grease to the contact surfaces of the rocker
arms and rocker arm pivots. Install the rocker
arms and rocker arm pivots on one cylinder head,
and start the two hex flange screws.
3. Torque the hex flange screws to 11.3 N·m
(100 in. lb.). See Figure 11-42.
Section 11
Reassembly
3. Install new plugs and torque to 24.4-29.8 N·m
(18-22 ft. lb.). See Figure 11-44.
Figure 11-42. Torquing Rocker Arm Screws.
4. Use a spanner wrench or rocker arm lifting tool
(see Section 2), to lift the rocker arms and
position the push rods underneath. See Figure
11-43.
Figure 11-44. Installing Spark Plugs.
Install Ignition Modules
1. Rotate the flywheel to position the magnet away
from the ignition module bosses.
Figure 11-43. Using Spanner Wrench to Lift Rocker
Arm Over Push Rod.
5. Repeat the above steps for the remaining
cylinder. Do not interchange parts from the
cylinder heads.
6. Rotate the crankshaft to check for free operation
of the valve train. Check the clearance between
the valve spring coils at full lift. Minimum
allowable clearance is 0.25 mm (0.010 in.).
Check Assembly
Important: Rotate the crankshaft a minimum of two
revolutions to check longblock assembly and overall
proper operation.
Install Spark Plugs
1. Use new Champion® (or equivalent) spark plugs.
2. Set the gap at 0.76 mm (0.030 in.).
Figure 11-45. Installing Ignition Modules.
2. On engines equipped with SMART-SPARK™, both
modules are installed the same way – with the
two tabs out. See Figure 11-46 and 11-52.
On engines not equipped with SMART-SPARK™
the modules are installed with the spark plug
lead wire from module always away from the
cylinder. On #1 cylinder, the single kill tab should
be towards you. See Figure 11-45. On #2 cylinder,
the single kill tab should be away from you (in).
3. Install each ignition module to the crankcase
bosses with the two screws (hex flange or allen
head, based on model). Slide the modules up as
far away from the flywheel as possible and snug
the screws to hold them in that position.
11.13
11
Section 11
Reassembly
4. Rotate the flywheel to position the magnet
directly under one ignition module.
5. Insert a 0.30 mm (0.012 in.) flat feeler gauge
between the magnet and the ignition module (see
Figure 11-46). Loosen the screws enough to allow
the magnet to pull the module against the feeler
gauge.
Figure 11-47. Installing Intake Manifold Gaskets.
Figure 11-46. Setting Ignition Module Air Gap.
6. Torque the screws to 4.0-6.2 N·m (35-55 in. lb.).
7. Repeat steps 4 through 6 for the other ignition
module.
8. Rotate the flywheel back and forth checking for
clearance between the magnet and ignition
modules. Make sure the magnet does not strike
the modules. Check the gap with a feeler gauge
and readjust if necessary. Final air gap:
0.280/0.330 mm (0.011/0.013 in.).
Figure 11-48. Installing Intake Manifold with Wiring
Harness (Aluminum Manifold Shown).
Install Intake Manifold
1. Install the intake manifold and new gaskets or
O-Rings (plastic manifold), with wiring harness
attached, to the cylinder heads. Slide any wiring
harness clips onto the appropriate bolts before
installing. Make sure the gaskets are in the proper
orientation. See Figures 11-47, and 11-48. Using
the sequence shown in Figure 11-49, torque the
four screws in two stages, first to 7.4 N·m
(66 in. lb.), then to 9.9 N·m (88 in. lb.).
4
3
1
2
Figure 11-49. Intake Manifold Torque Sequence.
11.14
Section 11
Reassembly
NOTE: If the wires were disconnected from the
ignition modules on engines with SMARTSPARK™, reattach the leads and seal the base
of the terminal connectors with GE/
Novaguard G661 (see Section 2) or Fel-Pro
Lubri-Sel dielectric compound. The beads
should overlap between the terminals* to
form a solid bridge of compound. See Figure
11-50. Do not put any compound inside the
terminals.
*The 24 584 15-S ignition modules have a
separator barrier between the terminals. On
these modules, seal the base of the
terminals, but it is not necessary to have
overlapping beads of sealant between the
connections.
Figure 11-52. Connect Leads on SMART-SPARK™
Ignition Modules.
Install Breather Cover and Inner Baffles
Sealant
Figure 11-50. Sealant Applied to Terminals.
2. Connect the kill lead to the tab terminal on
standard ignition modules. See Figure 11-51.
Figure 11-53. Breather Cover and Gasket.
RTV sealant was used on early models between the
breather cover and the crankcase. A gasket with
imprinted sealant beads is now used and
recommended. See Figure 11-53. Install as follows.
1. Be sure the sealing surfaces of the crankcase and
breather cover are clean of old gasket material or
RTV sealant. Do not scrape the surfaces as this
could result in leakage.
2. Check to make sure there are no nicks or burrs on
the sealing surfaces.
Figure 11-51. Connecting Kill Leads on Standard
Ignition Modules.
3. Position the breather gasket and cover on the
crankcase. Install the first two hex flange screws
in locations 3 and 4 shown in Figure 11-54. Finger
tighten at this time.
11.15
11
Section 11
Reassembly
Install Blower Housing and Outer Baffles
NOTE: Do not completely tighten screws until all
items are installed to allow shifting for hole
alignment.
1. Pull the wire harness and spark plug leads out
through the appropriate openings in the
shrouding. See Figures 11-57 and 11-58.
Figure 11-54. Installing Screws (Locations 3 and 4).
4. Install the inner baffles using the remaining two
hex flange screws (see Figures 11-55 and 11-56)
and finger tighten. Do not torque the screws at
this time; they will be tightened after the blower
housing and outer baffles are installed.
Figure 11-57. Wires on Starter Side of Engine.
Figure 11-55. Installing Inner Baffles.
Figure 11-58. Wires on Oil Filter Side of Engine.
2. Slide the blower housing into position over the
front edge of the inner baffles. See Figure 11-59.
Start a few of the screws to hold it in place.
Figure 11-56. Finger Tighten Two Remaining Cover
Screws.
11.16
Section 11
Reassembly
Figure 11-59. Installing Blower Housing.
3. Position the outer baffles and secure using the
four hex flange screws (two long, two short) in
the front mounting holes (into cylinder head),
including any lifting strap or attached bracket(s).
Install the two short screws in the upper
mounting holes of the outer baffles (into the
backing plates). See Figures 11-60 and 11-61. Use
the short screw on the left side to mount the wire
harness bracket. Be sure any leads are routed out
through the proper offsets or notches, so they will
not be pinched between the blower housing and
baffles. See Figures 11-57 through 11-59.
Figure 11-61. Tightening Short Screws for Outer
Baffles.
4. Tighten all of the shrouding fasteners. Torque the
blower housing screws to 6.2 N·m (55 in. lb.) in a
new hole, or to 4.0 N·m (35 in. lb.) in a used hole.
Torque the shorter M5 side baffle screws to
4.0 N·m (35 in. lb.). See Figure 11-61. Torque the
M5 side baffle screws (into cylinder head) to
6.2 N·m (55 in. lb.) in a new hole, or to 4.0 N·m
(35 in. lb.) in a used hole. Torque the two lower
M6 baffle mounting screws to 10.7 N·m
(95 in. lb.) in a new hole, or to 7.3 N·m (65 in. lb.)
in a used hole.
5. If the engine had a plastic flywheel that overlaps
the blower housing, reinstall it now. Torque the
mounting screws to 4.0 N·m (36 in. lb.). For a
metal screen, apply Loctite® No. 242 to screw
threads and torque the screws to 9.9 N·m
(88 in. lb.).
6. Torque the four breather cover screws to 7.3 N·m
(65 in. lb.) in the sequence shown in Figure 11-62.
11
1
3
Figure 11-60. Tightening Outer Baffle Front
Screws.
2
4
Figure 11-62. Breather Cover Fastener Torque
Sequence.
11.17
Section 11
Reassembly
Install Oil Sentry™ (If So Equipped)
1. Apply pipe sealant with Teflon® (Loctite® No.
59241 or equivalent) to the threads of the Oil
Sentry™ switch and install it into the breather
cover. See Figure 11-63. Torque to 4.5 N·m
(40 in. lb.).
2. Connect the wire lead (green) to the Oil Sentry™
terminal.
Figure 11-63. Oil Sentry™ Switch (Some Models).
Install Control Panel (If So Equipped)
1. Install the panel to the blower housing.
2. Connect the throttle control shaft to the throttle
control bracket.
3. Connect the choke control cable to the throttle
control bracket.
Figure 11-64. Rectifier-Regulator Ground Details.
2. Install the B+ terminal/lead into the center
position of the rectifier-regulator plug and
connect the plug to the rectifier-regulator. See
Figure 11-65.
4. Connect the Oil Sentry™ indicator light wires.
Reconnect Rectifier-Regulator
1. Install the rectifier-regulator in the blower
housing if removed previously, then connect the
rectifier-regulator ground lead with the washer
and the silver screw through the eyelet as shown.
If a grounding bracket is used, secure with the
mounting screw and washer, against the outer
side of the rectifier-regulator. See Figure 11-64.
Figure 11-65. Attaching Connector Plug.
SMART-SPARK™ Module
1. On engines with SMART-SPARK™, reinstall the
SAM module to the blower housing or cylinder
baffle. Do not over-tighten the retaining screws.
11.18
Section 11
Reassembly
Install Valve Covers
Three valve cover designs have been used. The earliest
type used a gasket and RTV sealant between the cover
and sealing surface of the cylinder head. The second
type had a black O-Ring installed in a groove on the
underside of the cover and may have metal spacers in
the bolt holes. The newest design uses a yellow or
brown O-Ring, and the bolt hole spacers are molded
in place. The tightening torque differs between gasket
and O-Ring style covers. Kits are available for
converting to the latest O-Ring type covers.
Differences are pointed out in the following
installation steps.
NOTE: Do not scrape old RTV sealant (if used) off
the sealing surface of the cylinder head as
this could cause damage and result in leaks.
The use of gasket remover solvent (paint
remover) is recommended.
1. If using the gasket or sealant type cover, prepare
the sealing surfaces of the cylinder head and
cover as directed in Service Bulletin 252. Refer to
Section 2, for approved sealants. Always use fresh
sealant – using outdated sealant could result in
leakage. With O-Ring type covers, make sure the
sealing surfaces are clean.
2. Make sure there are no nicks or burrs on the
sealing surfaces.
3. For covers requiring RTV sealant, apply a 1.5 mm
(1/16 in.) bead to the sealing surface of both
cylinder heads, install a new cover gasket on
each, then apply a second bead of sealant on the
top surface of the gaskets. For O-Ring type
covers, install a new O-Ring in the groove of each
cover. Do not use gaskets or RTV sealant.
4. Position the covers on the cylinder heads. Locate
the cover with the oil separator hole on the #1
cylinder. If loose spacers were used, insert a
spacer in each of the screw holes. Install the four
hex flange screws in each cover and finger
tighten.
Gasket/RTV style cover ..................... 3.4 N·m (30 in. lb.)
Black O-Ring style cover
w/shoulder screws ........................ 5.6 N·m (50 in. lb.)
w/screws and spacers ................... 9.9 N·m (88 in. lb.)
Yellow or Brown O-Ring style cover
w/integral spacers ......................... 6.2 N·m (55 in. lb.)
1
3
4
2
Figure 11-66. Valve Cover Fastener Torque
Sequence.
Install Carburetor
WARNING: Explosive Fuel!
Gasoline may be present in the carburetor and fuel system.
Gasoline is extremely flammable and its vapors can explode
if ignited. Keep sparks and other sources of ignition away
from the engine.
1. Install a new carburetor gasket. Make sure all
holes align and are open.
2. Install the carburetor, throttle linkage, choke
linkage, and governor lever as an assembly. See
Figures 11-67 and 11-68. If a plastic intake
manifold is used and/or the carburetor is
equipped with a fuel solenoid, reconnect the
ground and main leads. See Figure 11-69.
5. Torque the valve cover fasteners to the proper
specification using the sequence shown in Figure
11-66, unless the screws also attach the heavyduty air cleaner main support bracket or other
components. Installation and torquing of the
screws will be performed after these parts are
installed.
11.19
11
Section 11
Reassembly
Figure 11-67. Installing Carburetor, Throttle
Linkage, and Governor Lever.
Figure 11-70. Install Governor Lever to Shaft.
2. Make sure the throttle linkage is connected to the
governor lever and the throttle lever on the
carburetor. See Figure 11-71.
Figure 11-68. Installing Two-Barrel Carburetor.
Figure 11-71. Installing External Governor Controls
(One-Barrel Carburetor).
Two-Barrel Carburetor Models: Move the control
panel into position on the blower housing and connect
the choke linkage into the bushing/lever from the
backside. Make certain that the control shaft offset is
back and towards the #2 side cylinder. See Figure
11-72. Connect the throttle linkage and spring to the
governor lever. See Figure 11-73.
Figure 11-69. Installing External Governor
Controls.
Install External Governor Controls
1. Install the governor lever onto the governor cross
shaft. See Figure 11-70.
11.20
Section 11
Reassembly
Bushing
Lever
Choke
Linkage
Figure 11-72. Choke Linkage Details (Two-Barrel
Models).
Figure 11-74. Installing Lower Support Control
Bracket.
7. Secure the control panel to the blower housing
with the two screws (Models without a HeavyDuty Air Cleaner). See Figure 11-75.
Figure 11-73. Throttle Linkage Details.
3. Move the governor lever toward the carburetor as
far as it will go (wide-open throttle) and hold in
position.
4. Insert a nail into the hole on the cross shaft and
rotate the shaft counterclockwise as far as it will
turn, then torque the hex nut to 6.8 N·m
(60 in. lb.).
Figure 11-75. Installing Control Panel.
8. Assemble the throttle control shaft to the control
bracket.
9. Assemble the choke control to the control bracket.
5. Reconnect the lead wire to the fuel shut-off
solenoid if so equipped.
6. Install the lower support control bracket if
equipped with a control panel. See Figure 11-74.
11.21
11
Section 11
Reassembly
10. Connect the Oil Sentry™ Indicator light wires.
Attach governor spring to governor lever. See
Figure 11-76 and appropriate charts on pages
11.23 through 11.25.
2. One-Barrel Carburetor Models: Install the
standard throttle control bracket and the air
cleaner support bracket (if used) to the cylinder
heads using the four hex flange screws. Torque
the screws to 10.7 N·m (95 in. lb.) into new holes,
or 7.3 N·m (65 in. lb.) into used holes.
Figure 11-76. Connecting Governor Spring to
Governor Lever.
Figure 11-77. Standard Control Bracket.
Install Throttle and Choke Controls
1. One-Barrel Carburetor Models: Connect the
choke linkage to the carburetor and choke
actuator lever.
11.22
Section 11
Reassembly
Item
1
2
3
4
5
6
7
8
9
10
11
12
Description
Bracket, speed control
Clamp, cable (some applications)
Kill Switch (some applications)
Lever, choke (top position)
Lever, throttle control (middle)
Linkage, choke control
Lever, throttle actuator (bottom)
Screw, M5x0.8x20
Washer, wave
Washer, flat (3)
Spring, choke return
Nut, M5x0.8 lock
Figure 11-78. Throttle/Choke Control Bracket Detail.
3. Connect the governor spring from the throttle
control bracket to the appropriate hole in the
governor lever, as indicated in the applicable
chart. Note that hole positions are counted from
the pivot point of the governor lever.
6 mm Governor Lever and Hole Position/
RPM Chart
6
5
4
3
2
1
Governed Idle Hole
11
High Idle RPM
Governor Lever Governor Spring
Hole No.
Color Code
3801-4000
6
3601-3800
5
3451-3600
4
3301-3450
3
5
3101-3300
2951-3100
4
2800-2950
3
3750*
4
3150*
4
*5% Regulation (others 10%)
Clear
Clear
Clear
Clear
Purple
Purple
Purple
Clear
Purple
11.23
Section 11
Reassembly
8 mm Governor Lever and Hole Position/RPM Chart
4
3
2
1
Governor Lever
CV18 Engines
Intended
Maximum RPM
High Idle
3888
3780
3672
3564
3456
3348
3240
3132
3024
Standard
Throttle Control
Engine Mounted Throttle Control
Pivot Shaft
WOT
Spring Color
Hole No.
Spring Color
Hole No.
3600
3500
3400
3300
3200
3100
3000
2900
2800
Green
Blue
Orange
Clear
Red
Purple
Blue
Orange
Black
4
4
3
4
3
2
2
1
1
Orange
Green
Blue
Orange
Green
Blue
Purple
Blue
Green
4
4
4
3
3
3
2
2
1
CV20-740 Engines with 0.0299 + 0.003 in. Thick (22 GA) Throttle Limiter
Intended
Standard
Engine Mounted Throttle Control
Maximum RPM
Throttle Control
Pivot Shaft
High Idle
WOT
Spring Color
Hole No.
Spring Color
Hole No.
3888
3780
3672
3564
3456
3348
3240
3132
3024
3600
3500
3400
3300
3200
3100
3000
2900
2800
Green
Blue
Orange
Clear
Red
Purple
Blue
Orange
Black
4
4
3
4
3
2
2
1
1
Purple
Black
Red
Purple
Black
Red
Clear
Red
Green
4
4
4
3
3
3
3
2
1
CV17, CV20-740 Engines Without Throttle Limiter
Intended
Standard
Maximum RPM
Throttle Control
11.24
Engine Mounted Throttle Control
Pivot Shaft
High Idle
WOT
Spring Color
Hole No.
Spring Color
Hole No.
3888
3780
3672
3564
3456
3348
3240
3132
3024
3600
3500
3400
3300
3200
3100
3000
2900
2800
Red
Purple
Black
Red
Purple
Blue
Orange
Clear
Red
4
3
3
3
2
2
1
2
1
Blue
Orange
Black
Orange
Green
Blue
Orange
Black
Red
4
3
3
2
2
2
1
1
1
Section 11
Reassembly
8 mm Governor Lever and Hole Position/RPM Charts cont.
CV26, CV745 EFI Engines
Governor Shaft
Configuration
Standard
(Parent Material)
Intended
Maximum RPM
High Idle
3888
3780
3672
3564
3456
3348
3240
3132
3024
WOT
Standard Throttle Control
Spring Color
3600
3500
3400
3300
3200
3100
3000
2900
2800
Orange
Black
Red
Green
Red
Green
Blue
Clear
Clear
Hole No.
3
3
3
2
2
1
1
1
1
With WAWB (Wide Area Walk
Behind) Throttle Control
Spring Color
Hole No.
Red
Purple
Blue
Orange
Green
Red
Purple
Blue
Clear
3
3
3
2
2
1
1
1
1
CV750 Engines
Governor Shaft
Configuration
Standard
(Parent Material)
Intended
Maximum RPM
High Idle
3888
3780
3672
3564
3456
3348
WOT
With Governed Idle Systems
Spring Color
3600
3500
3400
3300
3200
3100
Clear
Orange
Blue
Red
Clear
Clear
Install Electric Starter Motor
1. Install the starter motor using the two hex flange
screws. Position the lift bracket as shown to also
secure the dipstick tube. See Figure 11-79. Some
inertia-drive starters have a pinion cover and
spacers on the starter bolts.
Hole No.
3
1
1
1
1
1
4. Install the dipstick tube and align the mounting
hole with the threaded hole in the lift bracket.
Secure with the M5 hex flange screw. Torque the
screw to 4.0 N·m (35 in. lb.). See Figure 11-80.
2. Torque the two hex flange screws to 15.3 N·m
(135 in. lb.).
3. On models with a solenoid shift starter, connect
the leads to the solenoid.
11
Lift Bracket/Dipstick
Tube Support
Starter
Figure 11-80. Installing Dipstick Tube.
Figure 11-79. Installing Starter and Lift Bracket.
11.25
Section 11
Reassembly
Install Fuel Pump
WARNING: Explosive Fuel!
Gasoline may be present in the carburetor and fuel system.
Gasoline is extremely flammable and its vapors can explode
if ignited. Keep sparks and other sources of ignition away
from the engine.
1. Install the fuel pump and lines as an assembly.
Connect the pulse line to the crankcase vacuum
fitting. See Figures 11-81 and 11-82.
NOTE: Fuel pumps may be made of metal or
plastic. If a new fuel pump is being
installed, make sure the orientation of
the new pump is consistent with the
removed pump. Internal damage may
occur if installed incorrectly.
Figure 11-82. Install Pulse Line.
3. Connect the fuel lines. See Figure 11-83.
Metal-Cased
Pulse Fuel Pump
Figure 11-83. Installing Fuel Line (Commercial
Mower Shown).
Plastic-Cased
Pulse Fuel Pump
Install Air Cleaner Assembly
Refer to Section 4 for the air cleaner reassembly
procedure.
Standard Air Cleaners
1. Connect the breather hose and attach the breather
separator to the valve cover. Position the hose in
the cutout of the blower housing (later models).
See Figure 11-84.
Figure 11-81. Reinstalled Fuel Pump.
2. Install the fuel pump using the two hex flange
screws. Torque the screws to 2.3 N·m (20 in. lb.).
11.26
Section 11
Reassembly
Lower Screws
Figure 11-84. Breather Hose and Separator Details.
2. Position a new gasket and the air cleaner base on
the studs while carefully pulling the loose end of
the rubber breather hose through the base until
properly seated (collars sealed against each side
of the base. See Figure 11-85.
3. Secure the air cleaner base and bracket, or spitback cup with baffle, using the hex flange nuts. If
a lower air cleaner bracket is used, install the two
M5 screws through the lower section of the base.
Torque the hex flange nuts to 6.2-7.3 N·m
(55-65 in. lb.), and the two lower M5 mounting
screws (when applicable) to 4.0 N·m (35 in. lb.),
See Figures 11-85 and 11-86.
Figure 11-86. Tightening Lower Base/Bracket
Screws (Some Models).
4. Install the air cleaner components as described in
Section 4.
Heavy Duty Air Cleaners
1. Install a new air cleaner base gasket.
2. Attach the main support bracket to the four
inboard valve cover screw locations. Make sure
each of the mounting holes has a loose or integral
spacer. Leave screws slightly loose.
3. Install the elbow adapter onto the mounting
studs. Secure with, and torque the hex flange nuts
to 6.2-7.3 N·m (55-65 in. lb.). See Figure
11-87.
Mounting
Nuts
11
Figure 11-85. Torquing Base and Spitback Cup
Mounting Nuts.
Figure 11-87. Torquing Hex Nuts (Two-Barrel Model
Shown).
4. Install and tighten the two mounting screws
securing the air cleaner mounting bracket and the
control panel to the blower housing. See Figure
11-88.
11.27
Section 11
Reassembly
Install Muffler
1. Install the port liners (if equipped). Install the
muffler and attaching hardware to the muffler
bracket. Torque screws to 9.9 N·m (88 in. lb.).
2. Install the hex flange nuts to the exhaust studs.
Torque hex flange nuts to 24.4. N·m (216 in. lb.).
Install Oil Cooler
If so equipped, the oil cooler can now be installed to
the engine. Two different styles are used, see Section 6.
Figure 11-88. Installing Upper Mounting Screws.
5. Torque the valve cover/mounting bracket screws
to the proper specification and torque sequence
listed under “Install Valve Covers” on page 11.19.
1. Depending on style used, reverse the removal
procedure from Section 9.
2. Secure the cooler or adapter to the oil pan with
the oil filter nipple. Torque the oil filter nipple to
27 N·m (20 ft. lb.).
Install Oil Filter and Fill Crankcase with Oil
1. Prefill a new oil filter following the instructions in
Section 6.
2. Apply a thin film of clean oil to the rubber gasket
on the oil filter and thread the filter onto the
adapter nipple. See Figure 11-91.
3. Hand tighten the filter until the rubber gasket
contacts the adapter, then tighten the filter an
additional 3/4-1 turn.
Figure 11-89. Securing Air Cleaner Mounting
Bracket.
6. Two-Barrel Carburetor Models Only: Attach the
choke return spring to the bottom of the main
control bracket. See Figure 11-90.
Choke Return
Spring
Figure 11-91. Installing and Tightening Oil Filter.
4. Install the oil drain plug(s). See Figure 11-92.
Torque plug(s) to 13.6 N·m (10 ft. lb.).
Figure 11-90. Attaching Choke Return Spring (TwoBarrel Carburetors).
11.28
Section 11
Reassembly
Prepare the Engine for Operation
The engine is now completely reassembled. Before
starting or operating the engine, be sure to do the
following.
1. Make sure all hardware is tightened securely.
2. Make sure the oil drain plugs, oil sentry pressure
switch, and a new oil filter are installed.
Drain Plug
Figure 11-92. Install Oil Drain Plug(s).
NOTE: Make sure that both oil drain plugs are
installed and torqued to the above
specifications to prevent oil leakage.
5. Add oil to bring the level up to the ‘‘Full’’ mark
and reinstall the dipstick.
Connect Spark Plug Leads
1. Connect the leads to the spark plugs. See Figure
11-93.
3. Fill the crankcase with the correct amount,
weight, and type of oil. Refer to oil
recommendations and procedures in the ‘‘Safety
and General Information’’ and ‘‘Lubrication
System’’ sections.
4. Adjust the carburetor, idle fuel needle, or idle
speed adjusting screw as necessary. Refer to
Section 5, ‘‘Fuel System and Governor’’.
Testing the Engine
It is recommended that the engine be operated on a
test stand or bench prior to installation in the piece of
equipment.
1. Set the engine up on a test stand. Install an oil
pressure gauge. Start the engine and check to be
certain that oil pressure (20 psi or more) is
present. Run the engine at idle for 2-3 minutes,
then 5-6 minutes more between idle and
midrange. Adjust the carburetor mixture settings
as necessary (as available).
2. Adjust the idle speed screw and high-speed stop
as necessary. Make sure the maximum engine
speed does not exceed 3750 RPM (no load).
11
Figure 11-93. Connect Spark Plug Leads.
11.29
FORM NO.: TP-2450-C
ISSUED:
3/94
REVISED:
3/06
LITHO IN U.S.A.
FOR SALES AND SERVICE INFORMATION
IN U.S. AND CANADA, CALL 1-800-544-2444
ENGINE DIVISION, KOHLER CO., KOHLER, WISCONSIN 53044
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