Diesel Injection Pump
The diesel injection pump is mounted at front left of engine. It consists of a vane-type transfer pump, governor, timing control, pressure valves, fuel shutoff valve, altitude/boost compensator, emergency stop lever, and fuel return orifice jet. The pump is driven by the timing belt at the same speed as the camshaft. The pump governs both injection time and the amount of fuel injected.
California models use a VP-20 injection pump. It functions in the same way as the Federal VE pump, except for the method of controlling the pump timing. The California model is controlled by a trunk-mounted fuel flow computer. The computer gathers information from the coolant temperature sensor, crankshaft position sensor, and the instrumented injector, then it varies the pump timing. See Fig 1 .
The transfer pump increases the fuel pressure to 36-116 psi (2.5-8.2 kg/cm2 ). This low pressure fuel then goes to the injection pump barrel/plunger chamber. The injection pump plunger (part of the cam disc), compresses fuel to over 2500 psi (176 kg/cm2 ). This high pressure fuel is distributed to the high pressure valves, delivery tubes, and injectors. See Fig 2 .