On a very cold engine, it may happen that the compression does not provide ignition temperature. In this case, the engine needs to warm up. For this, a glow plug is installed in each swirl chamber, which heats the combustion chamber. To make it easier to start a cold engine, the injection start of the high pressure fuel pump is set to an early injection. As the engine warms up to operating temperature, the injection start point moves to its normal position. In this case, the control unit for the start of injection is taken over by the DDE control unit (DDE - Digital Diesel Engine Management System), as well as controlling the amount of fuel injected and the discharge pressure of the exhaust turbocharger.
Fuel is supplied from the fuel tank by a fuel pump and a high pressure fuel distribution pump. The high pressure fuel pump generates a high pressure of about 160 bar required for diesel fuel injection and distributes it to the individual cylinders according to the ignition sequence. The amount of fuel injected is determined by the DDE control unit in accordance with the position of the accelerator pedal, using a signal from a potentiometer associated with it. At the right time, diesel fuel is injected by nozzles into the prechambers of the corresponding cylinders. Due to the shape of the swirl chamber, the air in the compression stroke receives a certain vortex movement, which ensures optimal mixing of the injected fuel with the air.
Before fuel enters the high pressure fuel pump, it passes through the fuel filter. However, fuel is only supplied if there is no air in the system. The filter collects contaminants and water. Therefore, it is extremely important to replace the filter in accordance with the maintenance schedule.
The high pressure fuel pump is maintenance free. Its high-pressure fuel pump is driven via a toothed belt, which also drives the camshaft.
Since the diesel engine has the property of self-ignition of the fuel mixture and therefore cannot be stopped by de-energizing the ignition system, it has a solenoid valve for this. When the engine is started, the solenoid valve is supplied with voltage from the ignition switch. When the ignition is turned off, the magnetic valve is de-energized and the valve closes the fuel supply channel, the engine stops. Thanks to the fuel cut-off relay, it is ensured that no fuel is supplied when the ignition key is removed. When the engine is started, the magnetic valve is recorded by the voltage from the ignition switch and opens the fuel supply channel.