DeVille V8-4.6L VIN Y (1998)
Fuel Hoses and Pipes: Description and Operation
Fuel and EVAP Pipes
The fuel feed (2), return (3), pipes carry fuel to and from the fuel rail as part of the fuel delivery system. The EVAP pipes (1) carries fuel vapors for the
EVAP components. Retaining clips (4/5) hold the pipes together and provide a means for attaching the pipes to the vehicle. Quick-connect type fittings
are used at the ends of the fuel feed and return 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 heat resistant rubber hose and/or coextruded conduit.
Nylon Fuel Pipes
Nylon fuel pipes are designed to perform the same function as the steel or rubber fuel pipes they replace. Nylon pipes are constructed to withstand
maximum fuel system pressure, exposure to fuel additives, and changes in temperature. Both fuel feed and fuel return pipe size is 5/16 of an inch ID. The
EVAP pipe from tank to canister size is 1/4 of an inch ID and from canister to engine is 5/16 of an inch OD. The vacuum signal pipe is 1/4 of an inch ID.
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. Also, once exposed to fuel, nylon pipes may become stiffer and more likely to kink if bent too far. Special care should be
taken when working on a vehicle with nylon fuel pipes.
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.)
