Fuel is sucked from the tank by a high-pressure fuel distribution pump. The high-pressure fuel pump (HPFP) creates the pressure necessary for injection (about 130 Bar) and the fuel is distributed between the cylinders in the order of ignition. At the same time, the regulator in the high-pressure fuel pump controls the injection quantity depending on the position of the gas pedal. Fuel is injected through the injectors into the swirl chambers of each cylinder. Due to the shape of the chamber, the air acquires a certain swirl motion during the compression stroke, which ensures optimal mixing of the injected fuel with air. Before entering the high-pressure fuel pump, the fuel passes through the fuel filter. Contaminants and water are retained there. It is extremely important to drain the sediment from the filter and replace it in accordance with the instructions.
The high-pressure fuel pump is maintenance-free. All moving parts of the pump are lubricated with diesel fuel. The high-pressure fuel pump is driven by the crankshaft via a toothed belt, through which the camshaft is also driven. Since the diesel engine operates with self-ignition and cannot be switched off by turning off the ignition system power supply, it has an electromagnetic valve. When the ignition switch is turned off, the electromagnetic valve power supply is interrupted, and the valve closes the fuel supply channel.
This ensures that the fuel supply is stopped before the steering column lock is locked. When the engine is started, voltage is supplied to the electromagnetic valve via the ignition switch, and it opens the fuel supply channel.
When working on the diesel engine injection system, cleanliness rules must be observed, see Chapter Power supply system, carburetor, fuel injection system, Chapter Cleanliness rules when working with the power supply system.