Power supply system diagram
The system is designed to clean and supply atomized fuel to the engine cylinders in the amount required for the corresponding operating mode.
The fuel system includes a rear-mounted fuel tank, fuel filter, high-pressure fuel pump, injectors, high-pressure and low-pressure fuel lines.
The booster pump built into the high-pressure fuel pump takes fuel from the tank and sends it to the filter. The filter retains mechanical impurities and water contained in the fuel. A manual fuel pump is mounted in the fuel pump body. After being cleaned in the filter, the fuel goes to the high-pressure fuel pump.
The amount of fuel supplied to the cylinders is regulated by a metering device controlled by a cable from the accelerator pedal. The injection advance angle changes depending on the engine speed.
There is an electromagnetic valve to stop the engine. When the engine starts, 12 V is supplied to the valve winding, the valve opens and passes fuel to the pump and injectors. When the engine is turned off, turning the key in the ignition switch turns off the fuel valve and shuts off the fuel supply.
The fuel pump delivers fuel under high pressure through pipelines to the injectors, which are installed in the cylinder head near the combustion chambers. The injectors inject fuel into the swirl chambers, where the fuel ignites.
The injectors are a valve that opens at a strictly defined fuel pressure (110–120 bar). The atomizer, located at the lower end of the injector, forms a spray of the required fuel shape. The fuel is cut off by a needle under the action of the injector spring. The atomizer and needle are precision units and require careful handling during repair. Excess fuel after the cutoff leaks along the needle, lubricating it, and is discharged into the tank through the return pipeline.
The serviceability and correct adjustment of the injectors are very important for the normal operation of the engine. If the injector spray does not provide the required torch shape or there is a bad cut-off, the engine begins to vibrate, strong mechanical knocks appear, and smoking increases.
Attention! Injection pressure is an adjustable parameter. During engine operation, injection pressure often drops, so the injector must be checked periodically and adjusted if necessary.
It should be noted that the nozzles from different engine models are externally identical, but have different characteristics, in particular, the shape of the torch, therefore new nozzles should be used only those designed for a given model.
To facilitate starting a cold engine, a system is used to improve fuel ignition in the cylinders at the moment of starting. Glow plugs are installed in the swirl chambers of each cylinder. Before starting the engine, voltage is supplied to them, which is indicated by the lighting of the control lamp on the instrument cluster. Within a few seconds, the plugs heat up to a high temperature and the control lamp goes out, which serves as a signal to start the engine. The hot plugs raise the temperature in the swirl chamber and facilitate fuel ignition. It should be noted that the plugs do not turn off immediately after starting the engine, but after some time, allowing the engine to reach normal operating mode. The failure of even one plug leads to difficult starting of the engine, with interruptions in operation and strong vibration.
The fuel system on diesel engines is usually very reliable. The main condition for normal and long-term operation is the purity of the fuel used and the absence of water in it.