Fuel Return Line: Description and Operation

Fuel Tank And Hoses:

FUEL AND VAPOR PIPES
The fuel feed and return pipes extend from the fuel pump/gauge sending unit to the engine compartment. The pipes are secured to the underbody with clip and screw assemblies. Both fuel feed pipes and return pipe must be properly routed and retained, and should be inspected occasionally for leaks, kinks, or dents. If evidence of dirt is found in the fuel injector assembly or fuel filter during disassembly, the pipes should be disconnected and blown out. Check the fuel strainer on the fuel pump/fuel gauge assembly for damage or omission.

The vapor pipe extends from the fuel pump/gauge assembly to the canister. However, it may not follow the same route as the fuel feed pipe.

Due to the fact that the fuel pipes/hoses are under high pressure on fuel injected systems these systems require special consideration for service.

NYLON FUEL LINES
Nylon fuel lines are designed to perform the same function as the steel or rubber fuel lines they are replacing. Nylon lines are made to withstand maximum fuel line pressure, exposure to fuel additives, and changes in weather. There are two sizes used: 3/8" ID for the fuel feed and 5/16" ID for the fuel return. The fuel feed and return lines are assembled and serviced as an assembly. Quick connect type fittings are used at the ends of the fuel feed/return lines and at the in-line fuel filter.

Nylon fuel lines are somewhat flexible and can be formed around gradual turns under the vehicle. Nylon lines, if forced into sharp bends, will kink and restrict fuel flow. Special care should be taken when working with nylon fuel lines. Nylon fuel lines cannot be repaired and can only be replaced with the proper part number replacement.

Nylon Fuel Line Tool:

QUICK CONNECT FITTINGS
Quick connect type fittings provide a simplified means of installing and connecting fuel system components. Two types of quick disconnect fittings are used at various parts of the fuel system. O-rings, located inside the female socket provide the fuel seal. One type quick disconnect fitting uses hand releasable locking tabs. The other type of quick disconnect fitting has a locking tab that requires the use of a special tool.


FUEL LINE O-RINGS
The fuel line O-rings used are made of Viton. They are brown in color. Viton is less affected than rubber by the additives used in many fuels. Therefore, rubber should not be used.