Yukon/Denali 2WD V8-4.8L VIN V (2005)
Fuel Return Line: Description and Operation
NYLON FUEL PIPES
CAUTION: Refer to Fuel and EVAP Pipe Caution in Service Precautions.
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: 9.5 mm (3/8 in) ID for the fuel supply, 7.6 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 protects the sections of the pipes that are exposed to chafing, to high temperatures, or to 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.
