Fuel Pump: Description and Operation
FUEL PUMP MODULEFuel Pump Module - Typical:
The fuel pump module contains the fuel pump, fuel reservoir, level sensor, and inlet strainer. The inlet strainer, level sensor and rollover valve are the only serviceable items. If the fuel pump requires service, replace the fuel pump module.
ELECTRIC FUEL PUMP
The fuel system uses a positive displacement, gerotor gear, 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 fuel pump module is suspended in fuel in the tank. The pump module 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 unregulated pressure output of approximately 871 kPa (125 psi). Without vacuum applied to the fuel pressure regulator, the regulator adjusts fuel system pressure to approximately 338 kPa (49 psi) on 3.5L engines. Fuel system pressure varies with different amounts of manifold vacuum.