Serviceable and well-adjusted fuel equipment ensures the supply of finely atomized fuel in equal portions and at a certain time to the combustion chambers of all cylinders. Fuel must be supplied in such an amount that is necessary to obtain the required engine power at a given crankshaft speed. Failure to comply with these requirements leads to excessive fuel consumption, reduced power and diesel engine service life.
When operating a diesel engine, malfunctions may occur in the power system, the main symptoms of which are:
- Increased fuel consumption.
- Unstable engine idling.
- The engine is not picking up speed.
- It is difficult to start the engine in cold weather.
- The car started to smoke (black, blue, white-gray smoke from the exhaust pipe).
- Loss of engine power.
- When the engine is loaded, a characteristic sound (crackling) is heard.
Malfunctions in the power supply system occur due to failures and damage to devices and fuel lines in the low and high pressure lines. The main faults in the low pressure line include leaks or clogging of fuel lines and filters, as well as malfunctioning of the low pressure pump, which leads to insufficient fuel supply to the high pressure pump.
Malfunctions in the high pressure line are reduced to malfunctions of the high pressure pump and injectors. They most often cause difficult engine start, interruptions and uneven operation of the cylinders, loss of engine power, increased smoke of the exhaust gases, refusals to control the crankshaft speed.
Leakage of the low pressure line occurs, as a rule, due to leaks in the connections. If such leaks appear in the line between the fuel tank and the low-pressure pump, then the fuel supply decreases sharply, the engine runs unstably at a low crankshaft speed and stops when the load increases.
When assembling the lines, complete tightness is achieved, especially at the connections to the fuel tank, coarse filter and low pressure pump.
Clogged fuel lines and filters in the low pressure line. The degree of clogging is judged by the decrease in fuel pressure in the line at the inlet to the high-pressure pump. Determine the value of the pressure on the control pressure gauge, which is connected to the hole for the plug to release air on the fine filter. If the pressure is below the permissible limit with tight connections, then replace the filter elements and check the operation of the low pressure booster pump.
Low pressure pump malfunctions cause a drop in pump performance and affect engine starting and operation. First of all, it becomes difficult to start the engine, since at a low crankshaft speed, the pump will supply less fuel even at a lower pressure. In the event of an increase in the load and at a low fuel supply by the pump, interruptions in the operation of the engine are observed and it will not be able to perceive the load.
The main causes of malfunctions and malfunctions of low pressure pumps are: debris and dirt under the valves, breakage or loss of spring elasticity, piston hanging, wear of the pusher rod. With increased wear of the main working surfaces of the pump (piston and cylinder), its performance decreases and the pressure in the line drops. A decrease in productivity can also occur when the elasticity of the working spring decreases.
Malfunctions of the high-pressure pump and injectors during operation can only be partially detected, most of them are determined only when checked using special equipment. Below are the main symptoms and nature of high pressure pumps and nozzles.
Difficulty starting the engine occurs due to wear of plungers, liners and pump discharge sections, breakage of plunger springs, discharge valves, lowering of injection pressure by injectors as a result of loss of elasticity of rod springs, development of nozzle openings of nozzles and violation of optimal pump adjustment.
Increased opacity of exhaust gases is observed with excessive fuel supply by the high-pressure pump sections, violation of the injection advance angle, decrease in the opening pressure of the injectors, jamming of the needle and increase in the nozzle openings of the injectors. In these faults, the exhaust gases are black.