Sunfire L4-2.2L VIN 4 (1996)
Modular Fuel Sender Assembly: Description and Operation
Modular Fuel Sender
The modular fuel sender assembly mounts in the top of the fuel tank and is spring loaded to the bottom. It is designed to:
^
Provide optimum fuel level in the internal fuel reservoir during all fuel tank levels and driving conditions.
^
Improve the measuring accuracy of fuel tank level.
^
Filters coarse contaminates from the fuel.
^
House fuel pump and helps prevent fuel pump noise.
^
Include a check valve to inhibit back flow of fuel from fuel system.
The fuel sender consists of the following serviceable components:
^
Fuel strainer
^
Level sensor.
^
Fuel tank vapor pressure sensor.
FUEL PUMP
An electric fuel pump (5) located in the modular sender assembly is used to provide fuel pressure. To control fuel pump operation, a fuel pump
relay and fuel pump switch are used. When the ignition lock cylinder is turned to RUN position, the fuel pump relay activates the electric fuel
pump for approximately two seconds to prime the injectors. If the PCM does not receive reference pulses after this time, the PCM opens the fuel
pump relay ground circuit. The relay will reactivate the fuel pump when the PCM receives reference pulses or when oil pressure raises.
FUEL PUMP STRAINER
A woven plastic strainer is located on the lower end of the fuel sender. This filter prevents dirt from entering the fuel line and also stops water
unless the filter becomes completely submerged in water. This filter 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. Therefore, should this occur, the fuel tank should be removed
and thoroughly cleaned and the tank filter replaced. Refer to Fuel System Cleaning in this section.
FUEL LEVEL SENSOR
The fuel sensor is attached to the modular fuel sender. The resistance of the fuel sensor changes with fuel by means of a rheostat. It ranges from 90
ohms with a full tank to 0 ohms with an empty tank.
FUEL TANK VAPOR PRESSURE SENSOR
The Fuel Tank Vapor Pressure Sensor (3) is mounted on top of the modular fuel sender. The sensor measures the difference between the fuel
vapor pressure (or vacuum) in the fuel tank and the outside air pressure. A three wire electrical harness connects it to the Powertrain Control
Module (PCM). The PCM supplies a 5 volt reference signal and ground to the sensor. The sensor will return a voltage between 0.1 volts and 4.9
