Fuel is taken from the tank by means of a vane booster pump built into the injection pump pressure head. Before entering the pump, the fuel passes through a filter that traps dirt and water. The injection pump is driven by a timing belt and its speed is half the speed of the crankshaft. The high pressure required to inject fuel into the swirl chambers is achieved by using two opposite pistons, which are pressed against each other by rollers rotating in a cam. The fuel passes through a central rotor which has a single outlet that aligns with the holes leading to the fuel injector tubes. Fuel dosing is carried out using a centrifugal regulator, which responds to the position of the gas pedal and engine speed. The regulator is connected to a metering valve that moves the rotor sleeve so as to increase or decrease the amount of fuel supplied to the pressure chambers. Injection timing (ignition timing) are changed by means of a cam to match the prevailing engine speed.
The engines in question have 4 precision injectors that inject a uniform jet of fuel into swirl chambers located in the cylinder head. The injectors are calibrated to open and close at specific pressures for efficient and even combustion. The needle of each injector is lubricated with fuel that accumulates in a special chamber and is directed to the high pressure fuel pump return hose through bypass pipes.
Depending on the model, a Bosch or Lucas CAV/Roto-Diesel fuel system can be installed. Parts of the latter are marked "Lucas CAV" or "Roto-Diesel" (depending on the date and place of manufacture). Glow plugs or glow plugs are placed in swirl chambers to make it easier to start a cold engine. There is also a thermostatic sensor in the cooling system that activates the fast idle lever to raise the engine speed and provide additional fuel to the engine during cold starts.
The cut-off solenoid cuts off the fuel supply to the injection pump rotor when the ignition is turned off. In addition, a manual cut-off lever is provided for emergency cases.
Maintenance of high pressure fuel pumps and injectors is reduced to only minor operations. All work, except for those specified in this chapter, must be carried out by a specialist.