Fuel Pump: Description and Operation

Fig. 3 Fuel Pump Module:

DESCRIPTION
The fuel pump module contains the fuel pump, fuel reservoir, level sensor, inlet strainer and fuel pressure regulator (Fig. 3). The inlet strainer, fuel pressure regulator and level sensor are the only serviceable items. If the fuel pump requires service, replace the fuel pump module.

OPERATION
The fuel system uses a positive displacement, roller vane, immersible pump with a permanent magnet electric motor. The pump draws fuel through a strainer and pushes it through the motor to the outlet. The pump contains two check valves. One valve relieves internal fuel pump pressure and regulates maximum pump output. The second valve, in the pump outlet, maintains pump pressure during engine off conditions. The fuel pump relay provides voltage to the fuel pump.

The fuel pump has a maximum deadheaded pressure output of approximately 635 kPa (95 psi). The regulator adjusts fuel system pressure to approximately 331 kPa (48 psi).

CIRCUIT OPERATION
Circuit A14 is a bus bar in the Power Distribution Center (PDC) and connects to battery voltage. The contact side of the fuel pump relay connects circuit A14 and circuit A141. A 20 amp fuse in the PDC protects circuits A14 and A142.

Circuit A141 supplies voltage for the fuel pump motor. Circuit Z1 provides ground for the fuel pump motor. The grounding point for circuit Z1 is the right rear wheel house.

Circuit F18 supplies voltage to the coil side of the fuel pump relay. The Powertrain Control Module (PCM) controls the ground path circuit for the coil side of the fuel pump relay on circuit K31. Circuit K31 connects to cavity 38 of the PCM.