GM LS Non-Return Fuel System Plumbing Kit with Walbro 255 Pump
WA01019
The GM LS Non-Return Fuel System Plumbing Kit is based on the same returnless fuel system layout used in Wide Open Design LS swaps, rock crawlers, race vehicles, and custom chassis builds. Designed for GM LS engines with factory-style non-return fuel rails, this system regulates fuel pressure near the tank and requires only a single supply line to the engine.
The kit combines a Walbro 255 LPH fuel pump with a filter/regulator assembly, Fragola -6 AN fittings, and 20 feet of premium nylon race hose. This layout reduces the number of lines routed through the chassis, simplifies installation, and helps create a cleaner engine bay while maintaining consistent fuel delivery for stock and moderately modified LS combinations.
Includes:
- (6) -6 AN Straight Hose-End Fittings
- (3) -6 AN 90-Degree Hose-End Fittings
- (1) 3/8" Quick-Disconnect to -6 AN Straight Adapter
- (1) 3/8" Quick-Disconnect to -6 AN 90-Degree Adapter
- (1) 5/16" Quick-Disconnect to -6 AN Adapter
- (1) 3/8" Female to -6 AN Adapter
- (1) Returnless Filter/Regulator Assembly
- (1) Walbro 255 LPH Fuel Pump with Sleeve and Clamps
- (2) Fuel Pump to -6 AN Fittings
- (20 ft) -6 AN Premium Nylon Race Hose
Note: Fuel tank fittings, electrical wiring, relay, fuse, hose supports, and application-specific mounting hardware may be required separately.
Specifications
| Specification | Details |
|---|---|
| Product Type | Non-Return / Returnless Fuel System Plumbing Kit |
| Engine Application | GM LS Engines and LS Swaps |
| Fuel Rail Configuration | Factory-Style Non-Return / Returnless |
| Fuel Pump | Walbro 255 LPH |
| Fuel Line Size | -6 AN |
| Hose Length | 20 Feet |
| Hose Type | Fragola Premium Nylon Race Hose |
| Fitting Brand | Fragola Performance Systems |
| Regulator Style | Filter/Regulator Combination Unit |
| Fuel Rail Connection | 3/8" Quick-Disconnect Supply Connection |
| Return Connection | 5/16" Quick-Disconnect at Filter/Regulator |
Fitment
Common Applications:
- GM LS engine swaps
- Factory-style returnless LS fuel rails
- Rock crawlers and rock bouncers
- Tube chassis buggies
- Ultra4 and off-road race vehicles
- Trail rigs
- Custom trucks and performance builds
Fitment Notes:
- Designed for LS fuel rails that require a single fuel supply line at the engine.
- The filter/regulator should be mounted near the fuel tank.
- A short return line is required from the filter/regulator back to the tank.
- Not intended for traditional return-style fuel rails without modifying the complete fuel system layout.
- Verify fuel rail quick-connect size before installation.
- Confirm that the pump, regulator, injectors, hose size, and fittings are suitable for the engine's horsepower and fuel type.
- Fuel pump wiring should use a properly sized relay, fuse, and power supply.
- Route fuel lines away from exhaust heat, sharp edges, suspension movement, and rotating driveline components.
- Secure hoses at regular intervals using fuel-compatible line clamps or supports.
Need a traditional return-style system? See the GM LS Return-Style Fuel System Plumbing Kit.
FAQ
What is a non-return LS fuel system?
A non-return system, also called a returnless system, uses a single fuel line from the tank area to the engine. Fuel pressure is controlled by a filter/regulator mounted near the tank, and excess fuel returns to the tank before it travels through the chassis.
Does a returnless system still use a return line?
Yes, but only near the tank. The filter/regulator sends excess fuel back to the tank through a short return connection. A second fuel line does not need to run from the engine bay back to the tank.
What fuel rails will this kit work with?
This kit is designed for factory-style GM LS fuel rails that use a single 3/8" supply connection and do not have a dedicated return port at the engine. Always verify the connection size and rail configuration before installation.
What are the advantages of a non-return system?
- Simpler fuel line routing
- Only one fuel line runs to the engine
- Cleaner engine compartment
- Fewer fittings and potential leak points
- Easier packaging in tube chassis and off-road vehicles
- Reduced fuel circulation through the engine bay
Is the Walbro 255 LPH pump suitable for an LS swap?
The Walbro 255 LPH pump is widely used in stock and moderately modified naturally aspirated LS combinations. Actual horsepower capability depends on fuel pressure, voltage at the pump, injector demand, fuel type, and the efficiency of the complete fuel system.
Can this kit support a high-horsepower LS engine?
This kit is best suited for stock and moderate-performance combinations. High-horsepower, forced-induction, high-ethanol, or race-only engines may require a larger pump, larger injectors, increased line size, and a different regulator configuration.
Why use nylon race hose?
Nylon race hose is lightweight, flexible, and easier to route through tight chassis areas than traditional stainless-braided hose. It still requires proper support, heat protection, and inspection to prevent abrasion or contact with moving components.
Where should the filter/regulator be mounted?
The filter/regulator should be mounted near the fuel tank so it can regulate pressure before the fuel travels to the engine. Keep the return connection short, mount the assembly securely, and protect it from exhaust heat, rocks, and suspension movement.
