Note: To check if fuel is being supplied to the injectors in case of difficult starting, loosen the union nuts on two injectors and start the engine without preheating until fuel comes out on the union nuts. Tighten the union nuts and start the engine according to the instructions.
Caution: If the air is not removed from the fuel system automatically, proceed as follows:
Fill the high-pressure fuel pump with diesel fuel.
Fill the fuel filter with diesel fuel.
Check the engine by towing the vehicle.
These measures can be used to quickly remove air. When working with the injection system, observe the cleanliness requirements.
Also, make sure that no fuel gets on the cooling system hoses. If necessary, the hoses should be cleaned immediately. Damaged hoses should be replaced.
Diesel fuel is sucked by the high-pressure fuel pump directly from the fuel tank. High fuel pressure is created in the high-pressure fuel pump (HPFP) (120-160 bar), which is injected into the cylinders in accordance with a given ignition sequence.
At the same time, the regulator in the injection pump controls the amount of fuel injected in accordance with the position of the gas pedal. Through the injectors, diesel fuel is injected into the pre-chamber of the desired cylinder at the required moment. Due to the shape of the pre-chamber and the swirl chamber, the intake air acquires a certain swirl motion during compression, so that the injected fuel is optimally mixed with the air.
Before the fuel enters the injection pump, it passes through a fuel filter. In the filter, the fuel is separated from dirt and water. Therefore, it is important to periodically drain the water from the filter and, if necessary, change the filter elements.
The high-pressure fuel pump does not require maintenance. All moving parts of the pump are lubricated with diesel fuel. The pump is driven by the crankshaft via a toothed belt.
The diesel engine operates on the principle of self-ignition. Therefore, it cannot be stopped by cutting off the voltage supply. A magnetic valve serves this purpose. When the ignition is turned off, the voltage supply to the magnetic valve is interrupted and the valve stops the fuel supply to the engine cylinders. This ensures that the fuel supply is stopped before the steering lock is fixed. When the engine is started, the ignition voltage is applied to the magnetic valve and the fuel supply to the engine opens.
This article was copied from an online resource: AudiManual.ru