Express 1/2 Ton Van V8-5.7L VIN R (1999)
Fuel Return Line: Description and Operation
CAUTION: In order to Reduce the Risk of Fire and Personal Injury:
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If nylon fuel pipes are nicked, scratched or damaged during installation, Do Not attempt to repair the sections of the nylon fuel pipes.
Replace them.
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When installing new fuel pipes, Do Not hammer directly on the fuel harness body clips as it may damage the nylon pipes resulting in a
possible fuel leak.
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Always cover nylon vapor pipes with a wet towel before using a torch near them. Also, never expose the vehicle to temperatures higher
than 115°C (239°F) for more than one hour, or more than 90°C (194 °F) for any extended period.
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Before connecting fuel pipe fittings, always apply a few drops of clean engine oil to the male pipe ends. This will ensure proper
reconnection and prevent a possible fuel leak. (During normal operation, the O-rings located in the female connector will swell and may
prevent proper reconnection if not lubricated.)
Nylon fuel pipes are designed to perform the same job as the steel or rubber fuel tubes they replace. Nylon pipes are constructed to withstand maximum
fuel system pressure, exposure to fuel additives and changes in temperature. There are two sizes used: 3/8 in. ID for the fuel feed and 5116 in. ID for the
fuel return.
The fuel feed and return pipes are assembled as a harness. Retaining clips hold the pipes together and provide a means for attaching the pipes to the
vehicle. Quick-connect type fittings are used at the fuel tank ends of the fuel feed/return pipes and at the in-line fuel filter. They are described below.
Sections of the pipes that are exposed to chafing, high temperature or vibration are protected with a heat resistant rubber hose and/or corrugated plastic
conduit.
Nylon fuel pipes are somewhat flexible and can be formed around gradual turns under the vehicle. However, if forced into sharp bends, nylon pipes will
kink and restrict fuel flow. Once exposed to fuel, nylon pipes may become stiffer and are more likely to kink if bent too far. Special care should be taken
when working on a vehicle with nylon fuel pipes.
