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Analysis of common failures of fuel injection pump
  • Automotive

(1) oil pump oil leakage. If the gap between the plunger and the plunger is too large, the oil will leak from the gap to the camshaft chamber, dilute the oil, destroy the lubrication condition of the injection pump and accelerate the wear of the parts. In addition, there will be low pressure leakage between the joint, sleeve and shell. (2) the oil of the injection nozzle caused by the failure of the oil discharge valve. There is a drop oil fault in the nozzle of the individual cylinder of the multi cylinder engine. The replacement comparison method can be used to check it. The "fault cylinder" injection nozzle is installed on the "normal cylinder" injection pump, such as dropping oil, indicating that the fault is on the injection nozzle; if no oil is dripped, it indicates that the fault is on the injection pump. In order to further identify the fault, the cam shaft cam cam of the cylinder can be turned to the lower stop point, the plunger is inserted into the oil hole and the high-pressure oil pipe is unscrewed and the oil supply of the pump is pressed by hand, because the oil supply pressure of the oil pump is lower than the opening pressure of the oil outlet valve, and the oil valve tight seat should be free of bubble or diesel spillover, otherwise the oil valve and seat will be closed. Not strict. If the oil flow is large, it indicates that the oil valve is stuck at the open position; if the oil flow is small, it indicates that the pressure relief ring and the sealing cone are worn seriously. For II pump, when the sealing gasket of the oil outlet valve is damaged, there will also be diesel overflow on the outlet valve seat. In order to distinguish, the cam cam cam can be transferred to the oil supply position again. Even if the plunger closes the plunger sleeve and the oil back hole, the oil is supplied with the hand pressure pump, and the oil out valve seat still has the diesel spillover, indicating that the fault is on the sealing washer of the oil outlet valve. The residual pressure of high pressure tubing is not as small as possible. Practice has proved that excessive residual pressure will cause cavitation, which will shorten the service life of high pressure tubing. Under normal wear condition, the wear of friction parts of relative moving parts increases gradually with the increase of service time. If the fuel or oil is unclean or the quality is poor, the wear will increase, or even the precision pair (such as plunger vice) will be invalid in the short term. (1) the cam wear of the injection pump camshaft causes the oil supply time to delay and the oil supply law change. Wear and tear of bearing and journal will cause the jitter of fuel supply rod to cause instability of diesel engine speed and affect the oil supply time and fuel supply pattern. (2) the wear of the oil supply rod and bushing hole will cause the oil supply rod to shake and cause the diesel engine speed to be unstable. When the diesel engine is serious, the adjustment arm is separated from the adjustment fork and the diesel engine flying car is caused. (3) plunger head, stop for the beveling and column insertion and return hole wear, reduce fuel supply and delay injection time. If the piston pair wear is uneven, the uneven supply of cylinders will cause instability of the diesel engine speed. When the wear is serious, no oil is supplied. (4) after the long time work of the oil outlet valve, its working surface will produce wear and tear, and the serious wear parts are the sealing conical surface and the pressure relief ring of the oil outlet valve and the inner hole surface. The wear of the sealing cone of the outlet valve pair causes the fuel supply to decrease and the injection time delay. The pressure reduction ring wear will make the oil breaking not crisp, the injection nozzle has dripping oil, the amount of oil supply increases, the injection time is ahead of time, which causes the unevenness of the oil supply of the cylinder and each cylinder to increase. For the old fuel injection pump, the reason for its stagnation is that the diesel is not clean. There are mechanical impurities between the plunger and the plunger sleeve, or the plunger and the plunger sleeve surface are pulled, or the burr is caused by the bump at the top of the plunger. When the fuel injection pump is assembled, if the connector is too tight, the plunger sleeve and the pump body are easily deformed, and the breakage will occur when it is serious. Or because of the improper assembly, it may cause the phenomenon of stagnation, or the oil has water, and the oil is too strong in winter, and the performance of the governor is destroyed. Even the performance of the governor is destroyed. Even the performance of the governor is destroyed. Even the performance of the governor is destroyed, even the performance of the governor is destroyed, even the performance of the governor is destroyed or even the performance of the governor is destroyed. Even The engine failure and the "runaway" phenomenon result in the destruction of the whole machine. Once the fuel injection pump has been deformed or cracked, new parts must be replaced. For the new fuel injection pump, the reasons for its stagnation are: (1) when the fuel injection pump is debugged, the diesel oil is not qualified, the gum content is large, and the acidity is high. After debugging, a layer of oil film is adhered to the matching surface of the fuel injection pump. If the fuel injection pump has been stored for too long, the oil film will gradually generate organic sediment and glue, and then it will produce stuck phenomenon after installation. (2) fuel injection pump storage is not good storage, packaging is not strict, moisture and rust proof material leakage or damage, oil pipe joint dust cap damage or loss, will also cause stagnation. Elimination method: for the old injection pump in use, we can find out the stuck plunger coupling and remove it and clean it with clean diesel oil. If the plunger coupling is damaged by mechanical impurities, it can be cleaned and cleaned with clean oil. For the new fuel injection pump, a suitable amount of gasoline or diesel can be injected into the injection pump and governor, and the camshaft is rotated repeatedly to make the pump tappet and governor fly ball moving freely, so as to prevent the rust and hairpin to lead to the diesel engine. (1) the fracture of the plunger spring. There may be a fracture phenomenon in the plunger spring in actual use, which may be caused by the following points: 1. The axial clearance of the camshaft is too large (often over 2 mm) or the positioning screw of the roller drive part is loose, causing the pump to produce pulse vibration during work, causing a violent impact between the roller transmission parts and the camshaft. It causes the plunger spring to fracture due to impact load. The axial clearance of camshaft should normally be controlled at about 0.10 mm. When the axial clearance is too large, the gaskets between the fuel injection pump connecting plate, the front shell of the governor and the fuel injection pump body can be reduced. 2. When the plunger spring is installed, the pre tightening force is too large or the spring force is not uniform. The elastic force of the plunger spring is too large or the quality is not good. The identification method of the elastic force of the plunger spring installed in the pump body is that if you can use the hand to rotate the plunger spring, it is not too laborious, that is, the elasticity is suitable. 4. The positioning shoulder of the plunger spring lower seat is not properly inserted into the wheel drive body or tilted during assembly. (2) repair of spring and spring seat. When checking the plunger spring, if cracks are found, the free length is shortened by 1 mm, and the distortion is more than 1 mm, new pieces should be replaced. When changing the new parts, the elasticity should be tested, and the elastic force must conform to the original regulations. (3) if the spring of the oil outlet valve is distorted or weakened, the new part should be replaced, and its elasticity should conform to the original factory regulations.

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