Impala V6-3.8L SC VIN 1 (2005)
Fuel Return Line: Description and Operation
FUEL FEED AND RETURN PIPES
The fuel feed pipe carries fuel from the fuel tank to the fuel rail assembly. The fuel return pipe carries fuel from the fuel rail assembly back to the fuel
tank. The fuel pipes consist of 2 sections:
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The rear fuel pipe assemblies are located from the top of the fuel tank to the chassis fuel pipes. The rear fuel pipes are constructed of nylon.
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The chassis fuel pipes are located under the vehicle and connect the rear fuel pipes to the fuel rail pipes. The chassis fuel pipes are constructed of
steel.
NYLON FUEL PIPES
Nylon pipes are constructed to withstand maximum fuel system pressure, exposure to fuel additives, and changes in temperature. There are 3 sizes of
nylon pipes used: 9.53 mm (3/8 in) ID for the fuel feed, 7.94 mm (5/16 in) ID for the fuel return, and 12.7 mm (1/2 in) ID for the vent. Heat resistant
rubber hose or corrugated plastic conduit protect the sections of the pipes that are exposed to chafing, high temperature, or vibration.
Nylon fuel pipes are somewhat flexible and can be formed around gradual turns under the vehicle. However, if nylon fuel pipes are forced into sharp
bends, the pipes kink and restrict the fuel flow. Also, once exposed to fuel, nylon pipes may become stiffer and are more likely to kink if bent too far.
Take special care when working on a vehicle with nylon fuel pipes.
