G-Body Return-Less Style Fuel Plumbing Kit
Part Number: 526-23
Holley’s GM G-Body Return-Less Style Fuel Plumbing Kit has the majority of parts and accessories for a complete plug and
play fuel system kit. It includes everything to take the guesswork out and not only replaces but upgrades the original fuel
system. Giving you all the flexibility while still maintaining a clean and easy OEM-like install.
Features:
Comes with everything needed to go from the fuel tank to the engine bay
Prepares your 1978-1988 GM G-Body for EFI
Simplifies your fuel system as a direct replacement
Pump gas and E85 compatible
Utilizes as many of the factory existing holes with no drilling required
Includes enough nylon braided hose to go from the tank to the fuel rail
Contains: AN fittings, 350 LPH EFI Fuel Pump Module, GM Style Filter/Regulator
New hardware and clamps
Pre-calibrated fuel level sending unit works with factory fuel gauge
Most complete solution for your G-Body
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Overview/Parts List:
General Layout for GM G-Body Return-Less Style Fuel System
Feed to rails/Sniper
PICTURE
QTY.
DESCRIPTION
HOLLEY REPLACEMENT P/N
1
Return-Style Fuel Pump Module 350 LPH
12-329
1
Fuel Pump Module Pigtail
---
2
3/8 Clamp
750006ERL
1
3/8 Hose
750066ERL
1
3/8 to AN Adapter
9002MRG
2
1/4 Clamp
---
1
1/4 Hose
---
1
1/4 to AN Adapter
9000MRG
3
90° Hose End
229006-BL
3
45° Hose End
224506-BL
1
Straight Hose End
220106-BL
2
1
120° Hose End
231206-BL
1
GM Style Filter/Regulator
162-591
1
Nylon Braided Hose
842006
5
5/8” P-Clamp
171010ERL
5
Self-Tapping Frame Bolts
---
1
1" Flame Guard
570010ERL
1
Fuel Pump Relay Kit
40205G
1
Split Wiring Loom
4505
1
20 Amp Fuse and Fuse Holder
---
Recommended Parts to Connect the Fuel Injection System:
NOTE: Some extra fittings are provided but depending on what type of engine is being used and how fuel is being delivered,
additional fittings may be necessary to adapt to the fuel injection system such as for LS engines:
Earls O.E. Fuel Line EFI Quick Connect
o
-6 AN to 3/8” OEM Fuel Tube (FEED)
Part #: 751166ERL
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Installation Instructions:
Read this manual before using this product.
WARNING! This instruction manual must be read and fully understood before beginning installation. If the
instructions are not fully understood, installation should not be attempted. Failure to follow the instructions may
result in subsequent system failure and could result in serious personal injury and/or property damage. Keep this
manual.
For the safety and protection of you and others as well as your vehicle, only a trained mechanic having adequate
fuel system experience should perform the installation, adjustment, and repair.
While undertaking any work involving the fuel system, it is particularly important to remember one of the very basic
principles of safety: fuel vapors are heavier than air and tend to collect in low places where an explosive fuel/air
mixture may be ignited by any spark or flame resulting in property damage, personal injury, and/or death. Extreme
caution must be exercised to prevent spillage and thus eliminate the formation of such fuel vapors. All work
involving this product and the fuel system generally MUST be performed in a well-ventilated area. Do NOT smoke or
have an open flame present near gasoline vapors or an explosion may result.
Any components damaged due to failure to follow these instructions will not be covered by the warranty. Failure of
any one component does not constitute, nor does it justify, warranty of the complete system. Individual service
items are available for replacement of components.
Holley Performance Products cannot and will not be responsible for any alleged or actual engine or other damage,
or other conditions resulting from misapplication of the fuel pumps and fuel pressure regulators described herein.
However, it is our intent to provide the best possible products for our customer; products that perform properly and
satisfy your expectations. Should you need information or parts assistance, please contact Technical Service at 1
(270) 781-9741, M-F, 8AM-6PM & Sat. 9AM-3PM CST. Please have the P/N ready when calling, thank you.
Tools Required:
7mm Socket
1/2” Socket
13mm Socket
15mm Socket
Ratchet
9” Extension
Flat Head Screwdriver
Rubber Mallet
Masking Tape and Marker
Pliers
AN Wrenches (P/N: 230351ERL)
Aluminum Vice Jaws (P/N: 1004ERL)
Adjustable Wrenches
Hose Cutting Shears
Earl’s Assembly Lube (P/N: 184004ERL)
Fuel Container
Jack and Stands
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NOTE: Due to manufacturers’ discrepancies, use these instructions as a general guide as some things
may differ from your certain application.
1. Prepping the car
a.) Fuel tank will need to be removed, so have little to no gas in the tank.
b.) If engine has been run within the past couple hours, let it cool down.
c.) Clean surrounding areas around the fuel rail/fuel injection system so that no dirt can get into engine.
d.) Ensure vehicle is parked on a flat, level surface.
e.) Engage parking brake.
f.) After relieving fuel pressure as mentioned below, remove negative (-) battery cable.
g.) Safely lift and support the vehicle securely with jack stands, and wear appropriate eye and ear protection.
2. Relieving Fuel System Pressure
a.) Ignition must be “off” and do not loosen any fuel system connections until relieving pressure as
recommended in your automotive service manual.
b.) Relieving fuel pressure can be done in numerous ways depending on the fuel delivery system, here’s some general
ways:
i. Throttle Body Injected Engines: Remove fuel pump fuse from the fuse box, start the engine until it runs
out of fuel and shuts off, continue by cranking engine over for 3 seconds to relieve any remaining fuel
pressure, and lastly, turn ignition off and reinstall fuel pump fuse.
ii. Port Injected Engines: Disconnect the fuel tank harness connector, start the engine until it runs out of fuel
and shuts off, continue by cranking engine over for 3 seconds to relieve any remaining fuel pressure, and
lastly, turn ignition off and reconnect fuel tank harness connector.
3. Fuel Tank Removal
a.) Remove fuel cap behind rear license plate.
b.) Disconnect Pink fuel sender wire connector and remove ground strap screw with 7mm socket.
Pull apart connector
Remove screw
c.) Remove fuel line clamp bolt with 1/2” socket and disconnect all (x3) hoses by relieving clamps with pliers.
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NOTE: Place fuel container underneath to prevent leakage onto floors.
Remove bolt
Remove
all 3 hoses
d.) Support fuel tank with a jack and use a 9” extension with 15mm socket to remove (x2) fuel tank strap bolts.
Remove bolts
NOTE: Fuel Tank not shown for visual purposes.
e.) Slowly lower fuel tank and remove the 3 remaining clamps with pliers to detach hardlines to drop tank.
4. Fuel Sender Removal
a.) Once tank is removed, clean surrounding areas around the fuel sender so that no dirt can get inside tank. With a Flat
Head screwdriver and Rubber mallet, remove the lock ring by rotating it counter-clockwise.
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5. Fuel Pump Module Install
a.) Lift up and remove the Fuel Sender as it will be replaced with an in-tank Fuel Pump Module.
NEW
OLD
b.) OE Style Fuel Pump Module has Hose Barb inlets, so we will convert the 3/8” Feed and 1/4” Return to AN. Using the
clamps, hose and the hose barb to AN adapter, tighten clamps with a 7mm socket
3/8 Clamp
3/8
3/8 to AN Adapter
3/8 Hose
NOTE: Do the same for the 1/4 Return.
3/8 Feed
1/4 Return
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NOTE: For non-baffled fuel tanks, we recommend Part #: 16-150, 19mm Outlet Offset HydraMat, to greatly
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reduce the potential of air entering the fuel system and limit fuel starvation during hard cornering, braking
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acceleration, inclines, and low fuel conditions.
c.
If upgrading with the new 16-150 HydraMat, install HydraMat by aligning the “V” shape of the rubber grommet to
arrow on the mat, press firmly to seat.
arrow
“V” shape
d. If aligned properly, the HydraMat’s short end points in the 10 o’clock position and the long end in the 4 o’clock
orientation. This maximizes the effectiveness of the mat and allows the short end of the mat to be tucked underneath
the internal wall inside the tank.
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12
9
3
9
6
6
Notice how the mat is tucked underneath
NOTE: Pump not shown for visual purposes
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e. Slide long end of the HydraMat first along with tucking in the fuel sender float arm into the hole entrance.
NOTE: Be cautious to not tear the HydraMat while inserting into tank.
f.
Lubricate the lock ring’s O-ring with Earl’s Assembly Lube.
Lube it
g. Seat lock ring and secure by rotating it clockwise with a Flat Head screwdriver and Rubber mallet.
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6. Factory Fuel Lines Removal
This kit replaces the factory fuel lines with Black Nylon Braided Hose. The factory fuel lines will need to be removed and new
hardware and clamps are provided.
a. Remove all bolts on passenger side frame rail that attach the fuel lines with a 1/2” socket.
Remove bolts
b. Completely remove all bolts and factory feed and return lines.
NOTE: Due to age and condition variances, we noticed some frame bolts were rusted, so we provided new frame
bolts that are self-tapping. They are not the same thread-pitch and will cut new threads, use as needed. If using,
position screw straight, aligning with hole and turn 1-2 turns by hand. Use 13mm socket to drive in new screw.
NEW vs OLD
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7. Mounting GM Style Filter/Regulator
a. Note the locations of the ports to properly plumb the filter/regulator, where the long-extended fitting returns back to
the fuel tank.
Return to Tank
Feed from Pump
Feed to Engine
b. Install 120° Hose End to “Feed to Engine” and two 45° Hose Ends on the other side where the long-extended fitting
“Returns back to the tank” and the other is the “Feed from Pump”.
Feed to Engine
120° Hose End
45° Hose End (x2)
Feed from Pump
Return to Tank
c.
Filter/Regulator’s mounting tab mounts with existing fuel line tab and is in alignment with one another.
Tabs align
Feed from Pump
Return to Tank
Feed to Engine
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8. Assembling AN Hose
AN fittings and hose will replace the factory fuel lines, here we’ll show a general way to assemble them:
a. Cut the hose square to the required length with Hose cutting shears or equivalent.
TECH TIP: Before cutting, wrap hose tightly with masking or electrical tape and cut through the tape.
v
This helps prevent the braid from fraying and trim any frayed ends with cutting pliers.
Mark the required
length to cut
Acceptable: hose is
cut square with little
to no fraying
Not Acceptable: cut
is not level,
excessive fraying.
Try again
b. Insert hose into socket by pushing and turning it clockwise until the hose butts against bottom of threads.
Hold socket stationary
Apply forward pressure
and rotate hose at the
same time into socket
Not Acceptable: Keep
pushing and twisting
to remove gap
Acceptable: hose is
bottomed out before
threads
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TECH TIP: Wrap tape around hose right against bottom of socket, this will be your visual aid to detect
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any tendency of the hose to be pushed out as you complete the assembly.
c.
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Lubricate inside of the hose and the fitting’s threads with Earl’s Assembly Lube.
Lube it
d. Holding the socket with Aluminum Vise Jaws, start the hose end by hand and then use AN wrenches or equivalent
(tape on adjustable wrenches) to tighten the fitting assembly.
Hold hose to help
prevent it doesn’t
back out of socket
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TECH TIP: Line up the flats on the hose end for that professional install while tightening, but don’t loosen.
Tighten until socket must be within 0.060” or less of bottoming on the hose end.
0.060” or less
Check the tape to see if the hose end has pulled away from the hose, if it did back out more than ~1/16” out of the
socket, try again by returning back to Step 12c.
1/16” or less
Remove the tape, and make sure your hose assembly is free of debris and thoroughly clean.
NOTE: Pressure test hose assembly to ensure no leaks. Further check the assembly by running the system at full pressure
pressu while you observe the hose, hose ends, and adapters for leaks.
WARNING! If metal cutoff wheel was used to cut hose, it is critical that you thoroughly clean the hose
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assembly and ensure it is free of any debris. Flushing the system prior to making the last
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connections to the fuel rails may be necessary to prevent any damage.
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9. Routing Fuel Hoses
With factory fuel lines removed, route the new Feed and Return Black nylon braided hoses in the same location as the
original lines. New 5/8” P-Clamps and Frame Bolts will be mounted using the same existing threaded hole locations. Thus,
these will be a direct replacement and will keep the fuel hoses in the OE location.
a. Using the General Layout in the Overview Section in Page 2 and the diagram below, route the new fuel hoses onto
the frame with the supplied 5/8” P-Clamps and tighten frame bolts.
A few guidelines to follow:
Ensure the insulated clamps are snug on the fuel hose to avoid droop and abrasion
Install Flame Guard over the feed hose near the exhaust manifold
Be cautious to avoid suspension, lift and frame pinch points
Keep hoses away from moving parts: axles, steering components, wheels, driveshaft, etc.
Avoid heat sources: engine, exhaust, heater hoses, etc. which can cause vapor lock or worse, a fire
Allow for bend radius, hose end length and offset to obtain length of hose required
All fuel line connections must be leak proof
TECH TIP: Label Feed and Return hoses to help distinguish which hose is which.
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b. Reference the following photos to aid installation:
Frame bolts (x5)
Frame bolts (x5)
Feed
Return
90° Hose End (x2)
Vent
NOTE: The 5/16” vent hose can be replaced with 3 feet of 750055ERL and clamps: 750005ERL (not supplied).
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Fuel hoses tucked on
passenger’s frame rail
Flame Guard
starts here
Flame Guard
ends here
NOTE: Again, some extra fittings are provided but depending on what type of engine is being used and how fuel is being
delivered, additional fittings may be necessary to adapt to the fuel injection system. Thus, we stopped at the engine bay to
give as much flexibility to plumb the last connections onto the fuel rail.
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14. Fuel Pump Wiring
Kit contains an Electric Fuel Pump Harness & Relay Wiring Kit. With couple modifications it can be a direct fit for your GBody. A plug and play harness for the fuel pump module and an in-line fuse holder with the recommended 20 Amp fuse is
included. Always crimp or solder connections and ensure surface is clean/grind where ground is connected. Cover it all up
with the provided split wiring loom for that factory-look install and you’re ready to go!
a. Follow the wiring instructions supplied with Holley® P/N 40205G and make the following modifications:
20 A
Black
Fuse Holder
Gray
Fuel Sender Pink
Gauge
(disconnected in Step 3b.)
Purple
15. Inspect for Leaks
Confirm all plumbing and wiring of the fuel system assembly is complete, with enough fuel in the tank, reconnect battery,
switch on the fuel pump but do NOT start the engine. Inspect all connections and components for leaks. If any leaks are
found, immediately de-energize the system and repair the leak(s).
16. Tank Installation
Once all plumbing and wiring connections have been made, the tank installs in the reverse order of removal.
WARNING! Any fuel that is spilled during any part of this installation must be immediately soaked up with r
shop towels/rags and removed from the vicinity of the vehicle.
17. Final Inspection
When all leaks have been repaired and system is leak-free, cycle the key between the on-and-off positions a few times to
build system pressure. At this point, ensure regulator is set to the desired pressure and adjust as necessary. Verify no leaks
and then, start the engine, after running for a few minutes but before driving, check for any leaks. If all is good,
congratulations, you did it and installation is complete! Enjoy some smiles per gallon!
Holley® Performance Products, Inc.
1801 Russellville Road
Bowling Green, KY 42101
Technical Support: 1-866-464-6553
Phone: 1-270-781-9741
www.holley.com
© 2022 Holley Performance Products, Inc. All rights reserved. Tous Droits Réservés.
199R12458
Date: 11-11-22
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