Fuel Pump
The BMW 2.4L diesel engine uses a solenoid-type electric fuel pump to transfer fuel from the fuel tank to the engine compartment. It also is used to assure pressurized fuel at the mechanical injection pump inlet.
The pressure limit provided by this fuel pump will allow for proper fuel metering of the mechanical injection pump. The fuel pump is located on the left engine mount between the engine starter motor and the mechanical fuel injection pump. The fuel lines route fuel from the fuel filter and heater assembly to the inlet of the electric fuel pump. Discharge flow goes directly to the inlet of the mechanical injection pump.
The electric fuel pump is a solenoid type that pulses a plunger at approximately 24 Hz. Proper flow direction and efficiency are assured by 2-way check valves located inside the fuel pump.
With the ignition switch in the "RUN" or "START" position, power flows to the fuel pump relay mounted on the left fender apron. When the relay closes, power flows from the battery through an 18 gauge fuse link at the starter relay, and turns the fuel pump on. In the event of an accident, the fuel pump shutoff switch opens and cuts off power to the fuel pump relay, turning off the fuel pump.