12.2. General information

Engines without turbo-supercharging

The fuel system of the diesel engine includes the fuel tank, the fuel pump of high pressure, the fuel filter installed on the fuel pump and the main fuel filter, the giving and returnable fuel-supply lines and fuel nozzles installed on one on each cylinder.

The fuel pump is put in action by a chain and rotates with turns twice smaller, than turns of a bent shaft of the engine. Fuel from the fuel tank gets the fuel pump via primary and main filter and then under high pressure moves to fuel nozzles.

The moment of injection of fuel is determined by turn of the fuel pump on fastening arms. During the operation of the engine the moment of injection is defined by mechanically fuel pump depending on the provision of a pedal of an accelerator and turns of the engine. The moment of injection of fuel can be changed by means of the adjusting device located sideways the fuel pump.

The fuel nozzle represents the valve which opens with strictly certain pressure of fuel. The spray which is on the lower end of a nozzle forms a torch of the sprayed fuel of the required form. The cut-off of fuel is made by a needle under the influence of a nozzle spring. The spray and a needle are knot of precision accuracy and demand the accurate address at repair. Surplus of fuel after a cut-off is pumped over along a needle, greasing it and on the return pipeline is taken away in the fuel tank.

Serviceability and the correct adjustment of nozzles are very important for normal operation of the engine. If the spray of a nozzle does not provide a torch of the required form or there is a bad cut-off, the engine begins to work with vibration, there are strong mechanical knocks, pressure increases. It should be noted that sprays from different models of engines are externally identical, but different characteristics have, in particular, the torch form therefore new sprays it is necessary to apply only those which are calculated on this model.

Switching off of the engine is made by means of the vacuum switch which is installed on the top part of the fuel pump of high pressure. At turn of a key in the ignition lock in the provision of "OFF" the vacuum switch connected to the ignition lock closes supply of vacuum to the vacuum switch which in turn blocks supply of fuel to the fuel pump, and the engine stops.

Adjustment of turns of idling of the engine is made by the mechanical regulator which is built in the fuel pump of high pressure. The mechanical regulator of centrifugal type changes the provision of a lath of the fuel pump via the sprung lever. Adjustment of turns of idling is carried out by one or more executive mechanisms which change idling turns at emergence of loading. For example, at turning on of the amplifier of steering, the conditioner, turning on of the drive on models with the automatic transmission or start of the cold engine.

On later models with 6-cylinder engines and models with 4-and 5-cylinder engines with the air conditioning system and the automatic transmission the electronic control system of turns of idling (ELR) is installed. In this system the electronic control device controls engine turns by means of the sensor installed about a flywheel and temperature of cooling liquid by means of the sensor which is screwed in in a head of the block of cylinders. The ECU block compares the actual sizes to the sizes which are written down in memory and if necessary turns on the electromagnetic executive mechanism which moves the regulator of the fuel pump and changes turns of idling of the engine.

On some models with the mechanical transmission the system preventing breakthroughs of the engine (ARA) is installed. This system on the basis of information on turns of the engine and temperature of cooling liquid excludes a possibility of emergence of breakthroughs of the car at acceleration and delay. At approach to a condition of breakthrough the executive mechanism installed sideways the fuel pump quickly reduces amount of the given fuel. As a result the torque of the engine decreases and the tendency to breakthrough vanishes. On models with 6-cylinder engines engine management is made by the electronic ELR device, and on other models the specialized electronic device.

Engines with a turbo-supercharging

Work of system of injection of fuel on engines with a turbo-supercharging is similar to work of system of injection of fuel on engines without turbo-supercharging. On engines a control system of turns of idling and excluding breakthroughs of the engine cope with a turbo-supercharging an electronic control system of diesel engines (EDS) which also operates pressure in system of repeated combustion of the fulfilled gases and a turbocompressor.

When working on fuel system, perhaps, a fuel effluence therefore it is necessary to be careful.


Do not allow hit of diesel fuel on cooling system hoses. Hoses which the long time influenced diesel fuel need to be replaced.

The fuel system of the diesel engine is especially sensitive to pollution therefore at work on fuel system observe the maximum purity. Before a rassoyedineniye of fuel-supply lines carefully clear them of dirt.

Do not use compressed air for cleaning of the elements of fuel system established on the engine.

When checking work of fuel nozzles never hold up hands or any part of a body under the fuel stream leaving a nozzle. Fuel comes out a nozzle under high pressure and can get into a body through skin.