With a diesel engine, the incoming clean air is subjected to a high degree of compression. Due to this, the temperature in the cylinders rises above the ignition temperature of diesel fuel. When the piston is in the position before TDC, diesel fuel is injected into compressed and heated to a temperature of +600°C air. Diesel fuel ignites on its own, spark plugs are not required here. On a cold engine, the required ignition temperature is not reached and therefore the engine needs preheating. To do this, a glow plug is placed in each vortex chamber.
Fuel is sucked from the tank by a high pressure fuel distribution pump. In the high pressure fuel pump (injection pump) pressure required 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 injection pump controls the amount of injection depending on the position of the gas pedal. Through injectors, fuel is injected into the swirl chambers of each cylinder. Due to the shape of the chamber, the air acquires a certain vortex movement during the compression stroke, which ensures optimal mixing of the injected fuel with the air. Before entering the injection pump, the fuel passes through the fuel filter. Dirt and water are trapped there. It is extremely important, in accordance with the instructions, to drain the sediment from the filter and replace it.
The high pressure fuel pump is maintenance free. All moving parts of the pump are lubricated with diesel fuel. The injection pump is driven by the crankshaft through a toothed belt, through which the camshaft is also driven. Since the diesel engine operates with self-ignition and cannot be turned off by turning off the power to the ignition system, it has a solenoid valve. When the ignition switch is turned off, the power supply to the solenoid valve is interrupted, and the valve closes the fuel supply channel.
This ensures that the fuel supply is cut off before the steering column lock is locked. When the engine is started, the solenoid valve is energized through the ignition switch, and it opens the fuel supply channel.
When working on the injection system of a diesel engine, the rules of cleanliness must be observed, see Chapter Power system, carburetor, fuel injection system, Chapter Rules for cleanliness when working with the power system.