This article introduces the inspection, adjustment, and maintenance suggestions of the fuel injection pump from 10 aspects.
The role of diesel fuel injection pump
The diesel fuel injection pump is to increase the oil pressure, control the fuel injection time and the fuel injection amount. It is an important component of the diesel fuel supply system. Its working condition directly affects the power, economy, and reliability of the diesel engine; the diesel engine is properly maintained The fuel injection pump is an important prerequisite for ensuring the normal operation of the fuel injection pump and extending its service life.
1. Use clean diesel
In order to ensure the normal operation of the fuel injection pump, the diesel entering the fuel injection pump must be highly clean. Any impurities in the diesel will cause severe corrosion or wear on the plunger of the fuel injection pump, the fuel injection valve coupler, and the transmission parts. For this reason, in addition to the quality and brand of the diesel selected for the diesel engine must fully meet the requirements, it should also be precipitated at least 48h. In addition, the cleaning and maintenance of the diesel filter should be strengthened, and the filter element should be cleaned or replaced in time; according to the operating environment conditions, the diesel tank should be cleaned in time to completely remove the sludge and moisture at the bottom of the fuel tank.
2. Check the lubrication
The quantity and quality of the oil in the fuel injection pump must meet the requirements (except for the fuel injection pump that is forcedly lubricated by the engine). If the oil is deteriorated due to the mixing of water or diesel, the lighter will cause early wear of the plunger and the oil outlet valve coupler, resulting in insufficient power of the diesel engine. It is difficult to start, and it will cause corrosion and rust of the plunger and the oil outlet valve in serious cases, so it is necessary to check the quantity and quality of oil in the fuel injection pump frequently. In addition, due to the internal leakage of the oil pump, the poor operation of the oil outlet valve, the wear of the oil pump tappet and the casing, and the damage of the seal ring, the diesel oil will leak into the oil pool and dilute the engine oil, so it should be replaced in time according to the quality of the engine oil. Thoroughly clean the oil sump and remove impurities such as sludge at the bottom of the oil sump, otherwise, the engine oil will deteriorate after a short period of use. The amount of oil should not be too much or too little. Too much oil in the governor can easily lead to a “speeding” of the diesel engine: too little oil and poor lubrication, the oil dipstick or oil plane screw shall prevail. In addition, when the diesel engine is not used for a long time, be sure to check whether there are impurities such as water and diesel in the oil in the oil sump of the oil pump. If there is any need to replace it immediately, otherwise the plunger and the oil outlet valve will be easily caused by moisture due to long-term storage The rust is stuck and scrapped.
3. Check the oil supply advance angle and the oil supply interval angle of each cylinder
In use, due to the loosening of the coupling bolts of the coupling, the wear of the camshaft and the roller body parts often leads to changes in the fuel supply advance angle and the fuel supply interval angle of each cylinder, which makes the diesel combustion worse, and the power and economy of the diesel engine The sex becomes worse, at the same time it is difficult to start, the operation is unstable, abnormal noise and overheating are made. In actual use, most drivers attach importance to the inspection and adjustment of the overall fuel advance angle but ignore the inspection and adjustment of the fuel supply interval angle (involving the adjustment of the single pump fuel advance angle). However, due to the wear of the camshaft and roller transmission components, the fuel supply of the remaining cylinders is not necessarily timing. It will also cause difficulties in starting the diesel engine, insufficient power, and unstable operation, especially for fuel injection pumps that have been used for a long time. That said, more attention should be paid to the inspection and adjustment of the fuel supply interval angle.
4. Check and adjust the oil supply of each cylinder
Due to the wear of the plunger assembly and the fuel outlet valve assembly, the diesel leakage is caused, the fuel supply of each cylinder is reduced or uneven, resulting in difficulty in starting the diesel engine, insufficient power, increased fuel consumption, and unstable operation, so regular Check and adjust the fuel supply of each cylinder of the fuel injection pump to ensure the power of the diesel engine. In actual use, the amount of fuel supplied by each cylinder can be determined by observing the exhaust of the diesel engine, listening to the sound of the engine, and touching the temperature of the exhaust branch.
5. Check the camshaft clearance
The axial clearance of the camshaft of the fuel injection pump is very strict, generally 0.03~0.15mm. If the clearance is too large, it will aggravate the impact of the roller transmission components on the cam working surface, thereby increasing the early wear of the cam surface and changing the oil supply advance angle. ; If the axial gap of the camshaft is too large, it is easy to cause the camshaft to run unsteadily, and the fuel supply adjustment rod jitters. The fuel supply amount changes periodically, which makes the diesel engine run unstable. Therefore, it is necessary to regularly check and adjust. When the axial clearance of the camshaft is too large, shims can be added on both sides to adjust. If the radial clearance is too large, it is generally necessary to replace new products.
6. Check the sealing of the oil valve coupler
The fuel injection pump works for a period of time. By checking the seal of the oil valve, you can make a rough judgment on the wear of the plunger and the working condition of the oil pump, which is conducive to the determination of repair and maintenance methods. During the inspection, unscrew the high-pressure fuel pipe joints of each cylinder and use the hand pump of the oil pump to pump oil. At this time, it is found that there is oil flowing out of the fuel pipe joint on the top of the fuel injection pump, indicating that the oil outlet valve has a poor seal (of course, the spring of the oil outlet valve will also break. In this case), if the multi-cylinder has a poor sealing phenomenon, the fuel injection pump should be thoroughly debugged and maintained, and the coupling should be replaced.
7. Selection of standard high-pressure tubing
During the fuel supply process of the fuel injection pump, due to the compressibility of the diesel and the elasticity of the high-pressure fuel pipe, the high-pressure diesel will form pressure fluctuations in the pipe. It takes a certain time for the pressure wave to pass through the pipe. In order to ensure that the fuel supply interval angle of each cylinder is consistent, the fuel supply The quantity is uniform and the diesel engine works smoothly. The length and diameter of the high-pressure fuel pipe are selected through measurement and calculation. Therefore, when the high-pressure fuel pipe of a cylinder is damaged, the standard length and diameter of the oil pipe should be replaced. In actual use, due to the lack of standard tubing, another tubing is often used, regardless of whether the length and diameter of the tubing are the same so that the tubing length and the tubing diameter vary greatly. This can cause an emergency, but it will cause the cylinder The oil supply advance angle and the oil supply amount change, which makes the whole machine work unstable. Therefore, in actual use, a standard high-pressure fuel pipe must be used.
8. Check the wear of the relevant keyway and fixing bolts
Related keyways and bolts mainly refer to the camshaft keyway, coupling flange keyway (oil pump that transmits power with a coupling), semicircular chain, and coupling fixing bolts. Due to the long-term use of the camshaft keyway, flange keyway and semicircular key of the fuel injection pump, the lighter will wear out, making the keyway wider, the semicircular key is not installed firmly, and the advance angle of fuel supply will change; the heavy chain will fall off, resulting in power transmission failure; Therefore, regular inspections are required to repair or replace worn parts in time.
9. Replace the worn plunger and oil outlet valve in time
When it is found that the diesel engine is difficult to start, the power is reduced, and the fuel consumption is increased, the adjustment of the fuel injection pump and the fuel injector still does not improve. The plunger of the fuel injection pump and the fuel outlet valve couple should be removed and inspected To a certain extent, it should be replaced in time, and do not insist on reuse. The loss of diesel engine start-up, fuel consumption, and insufficient power caused by the wear of the coupling parts far exceed the cost of replacing the coupling parts. The power and economy of the diesel engine will be significantly improved after the replacement. To be replaced.
10. Maintenance of fuel injection pump accessories
The side cover of the pump body, the dipstick, the oil filling plug (respirator), the oil spill valve, the oil pool plug, the oil level screw, the oil pump fixing bolt, etc. must be intact, these accessories are essential to the work of the fuel injection pump The role. For example, the side cover can prevent the intrusion of dust, moisture, and other impurities. The respirator (with filter) can effectively prevent the deterioration of the engine oil. The oil spill valve ensures that the fuel system has a certain pressure without entering the air. Therefore, these accessories must be strengthened and maintained. , If it is found damaged or lost, it should be repaired or replaced in time.