Fuel Injection System - Diesel: Description
Diesel mechanical fuel injection systems differ greatly from electronic fuel injection systems. In this diesel system, a mechanical high pressure rotary pump is gear driven by the camshaft at camshaft speed. Through this method the pump injects a precisely metered amount of fuel into each cylinder at the proper time. The pump is mounted on top of the engine and provides necessary timing advance under all operating conditions.
Eight high pressure fuel pipes carry fuel from pump to an injection nozzle in each cylinder. All 8 pipes are exactly the same length to ensure that there is no variance in timing. Engine RPM is controlled by a rotary fuel metering valve. As the accelerator pedal is pushed down, a throttle cable opens the metering valve and allows increased fuel delivery. A mechanical fuel pump located on the right side of the engine, draws fuel from the fuel tank and delivers it to the injection pump.
Three fuel filters are used to remove foreign material which could damage injection pump. The fuel tank filter screens out water from the fuel and allows it to collect at the bottom of the tank below the fuel pickup. When the water reaches a level where it could be drawn into the fuel supply, a dash-mounted warning lamp is energized. When the lamp is energized, water collected in the tank can be siphoned off at the shut off point. The primary fuel filter is located between the mechanical fuel pump and the fuel tank (mounted on firewall). The secondary fuel filter is located between the mechanical pump and injection pump (mounted on side of engine block). Any excess fuel is returned to the tank by a fuel return system.