Caprice Wagon V8-350 5.7L VIN P SFI (1996)
Fuel Tank Unit: Description and Operation
Fuel Sender Assembly
DESCRIPTION
The fuel sender assembly is inside the fuel tank attached to the top of the fuel tank. The fuel sender assembly consists of the following major
components:
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The fuel sender (1).
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The fuel pump (3).
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The fuel pump strainer (2).
Fuel Sender
The fuel sender consists of a float, a wire float arm, a rheostat, and a roll-over valve. Fuel level is sensed by the position of the float and float arm
which operate the 90 ohm rheostat. As the float position changes, the amount of current passing through the rheostat varies, thus changing the
gauge reading on the instrument panel. The EVAP pipe of the fuel sender has a pressed in roll-over valve. The roll-over valve prevents fuel from
entering the evaporative emission canister if the vehicle rolls over by shutting OFF the EVAP pipe to the canister.
Fuel Pump
The fuel pump attaches to the fuel sender assembly inside the fuel tank. The fuel pump is an electric medium pressure twin turbine pump. The fuel
pump pumps fuel to the fuel rail assembly at a specified flow and pressure. Excess fuel returns to the fuel tank by the return pipe. The fuel pump
delivers a constant flow of fuel to the engine even during low fuel conditions and aggressive vehicle maneuvers. The PCM controls the electric
fuel pump operation through a fuel pump relay.
Fuel Pump Strainer
The fuel pump strainer attaches to the lower end of the fuel pump. The fuel pump strainer is made of woven plastic. The functions of the fuel pump
strainer are to filter contaminants and to wick fuel. The fuel pump strainer is self-cleaning and normally requires no maintenance. Fuel stoppage at
this point indicates that the fuel tank contains an abnormal amount of sediment or water. Clean the fuel tank and replace a plugged fuel pump
strainer with a new one.
