Fuel Pump: Description and Operation

ELECTRIC FUEL PUMP
The fuel system uses a positive displacement, gerotor, 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 fuel pump has a maximum unregulated pressure output of approximately 862 kPa (125 psi). The regulator adjusts fuel system pressure to approximately 379 kPa (55 psi). The other valve, in the pump outlet, maintains pump pressure during engine off conditions. The fuel pump relay provides voltage to the fuel pump.

CIRCUIT OPERATION
Fuel Pump Motor
The fuel pump motor, located in the fuel tank, is controlled by the fuel pump relay located in the Power Distribution Center (PDC). Power for the coil side of the fuel pump relay is supplied on circuit F12. This circuit is HOT when the ignition switch is START or RUN position and protected by a 10 amp fuse located in cavity 10 of the fuse block.

Ground for the fuel pump relay, coil side, is controlled by the Powertrain Control Module (PCM) on circuit K31. This circuit connects to cavity C19 of the PCM.

Power for the contact side of the relay is supplied on circuit F241. This circuit is HOT at all times and protected by a 25 amp fuse located in cavity 4 of the PDC. Power for the fuse is supplied on circuit A12.

When the PCM provides a ground path for circuit K31, the contacts in the relay CLOSE connecting circuits F241 and A141. Circuit A141 connects from the fuel pump relay to the fuel pump motor. Ground for the fuel pump motor is supplied on circuit Z1, and Z12.