The diesel injection pump is mounted on top of the engine. It is gear driven by the camshaft and turns at camshaft speed. A light pressure rotary pump injects a metered amount of fuel into each cylinder at the precise time. Fuel delivery lines are the same length to prevent any difference in timing, from cylinder to cylinder. The timing advance is also controlled by the fuel pump. Engine rpm is controlled by the rotary fuel metering valve.
The fuel filter is located between the fuel pump and the injection pump at the left rear of the engine.
An electric fuel pump is used which is located at the front of the engine next to the fuel heater. Excess fuel returns to the tank via the fuel return line.
Because of the exacting nature of the diesel injection system all major repairs should be referred to your local GM dealer.