Fuel Injection System - 6.9L Diesel: Description

In this diesel system, a mechanical high pressure rotary pump is gear driven 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 engine and provides necessary timing advance under all operating conditions.

Eight high pressure fuel pipes carry fuel from pump to an injector in each cylinder. All 8 pipes are 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 via a fuel filter.

The fuel filter is located between the mechanical pump and injection pump (mounted on side of engine block). Any excess fuel in the supply system is returned to the tank by a fuel return system. A water separator is located in the fuel line between the tank and the mechanical fuel pump. The separator collects water out of the fuel system. When separator becomes about 1/3 full, a warning light on the dash will illuminate. When the warning light illuminates, water should be drained from the separator. The warning light will also illuminate when the key is in the "START" position to serve as a light test.

A solid state glow plug system is used to assist in engine starting and cold operation. A glow plug is located in the pre-chamber for each cylinder. Glow plug current is controlled by the controller module which incorporates the glow plug controller, power relay and afterglow relay into one unit.