Cummins diesel engine running power failure how to diagnose and eliminate
(1) Common causes of failure of Cummins diesel engine operation Diesel engine powerlessness refers to the lack of power during operation, poor acceleration, and the speed can not be increased to the proper range. The prerequisite for the sufficient power for the diesel engine to operate is that the crank connecting rod mechanism, gas distribution mechanism, lubrication system and cooling system are in good condition. If the above-mentioned organization and system are in good technical condition and the diesel engine is still inoperative, it should be a fault in the diesel fuel supply system.
Failure of the diesel engine oil supply system with the following failures will result in power failure: blockage, rupture of the tubing, or oil leakage from the fittings; air or water in the oil circuit; blocked or unsealed diesel filter; limited pressure valve is not sealed and the spring is too soft The oil pressure is too low; the oil pump is not working properly or the oil filter mesh is blocked; the plunger of the fuel injection pump cannot be returned due to the return spring being broken, or the plunger even wears; the adjustment lever of the oil supply lever or the column Plug sleeve fan loose; Outlet valve parts close loose or spring break; Oil supply time is too early or too late or the adjustable part of the coupling is loose; Injector due to premature wear of the needle valve Needle valve cone seat is not sealed; injector spring is broken or improperly adjusted, etc. The injector pressure is too low; injector needle stuck, resulting in failure to open and close; injector orifice blocked or poorly sprayed The oil supply rod or the governor moving piece is issued, the spring of the governor is broken, causing the oil supply rod to fail to reach the rated oil supply position; the diesel oil is mixed with moisture; the governor is improperly adjusted, which causes the high speed effect to work too early. The engine can not reach Reference speed; et rated amount of oil adjusted too low or too high.
(2) Factors influencing the combustion quality of diesel engines 1 The fuel system is not working properly, mainly because the fuel supply of the fuel injection pump is insufficient, the oil supply time is not correct, and the plunger pair and the check valve are worn out.
2 The state of diesel engine technology is declining. After long-term operation of the diesel engine, all the moving parts wear and the clearance increases, especially the sealing of the combustion chamber components deteriorates and the leakage increases. For example, pistons, piston rings and cylinder liners wear out, and the compression force inside the cylinder is insufficient. The combustion quality is affected, and the energy loss is greatly increased, causing the diesel engine to start difficultly and the power is reduced; the intake pipe or the air filter is blocked, so that the intake air quantity is insufficient; the valve clearance is too large or too small, and the valve spring is broken or has insufficient rigidity.
(3) The diagnosis and exhaustion method of Cummins diesel engine running power failure The diesel engine running power is divided into two situations. On the one hand, due to insufficient torque, the vehicle feels powerless when it is running on a heavy or soft road, or the acceleration is not sensitive and the climbing ability is improved. On the other hand, the engine is not able to reach the maximum speed due to insufficient rotation speed, and the running speed is low.
Inadequate torque due to engine operation, due to improper injection pump stroke adjustment; low pressure oil line blocked; air filter blocked; diesel in water; Improper adjustment and so on. When troubleshooting, check whether the pressure of oil is normal. If it is normal, check the work of the governor. During the inspection, first pull out the fuel supply pull button, then push the throttle test. If the acceleration is rapid and a lot of black smoke is discharged from the exhaust pipe, it means that the original fuel supply is insufficient, and the fuel pump can be unloaded together with the governor. Bench test. If the oil pressure is normal, there will be a slight shaking phenomenon and a knocking sound when the engine runs rapidly, and the exhaust pipe will emit a small amount of black smoke. This is generally because the oil supply is too early and should be adjusted. If the oil pressure is normal, the engine will not run smoothly, the exhaust pipe will emit white smoke, and it will be large and small like the steam. After the oil cut test, the work of each cylinder is almost the same. It may be that there is water in the diesel.
The engine is weak due to insufficient speed. The reason is that the governor is improperly adjusted or the spring is too soft and breaks. There is water in the diesel. The water is evaporated into steam in the cylinder and emerges from the exhaust pipe. When troubleshooting, check whether the fuel supply is good. If the fuel supply is good and there is a symptom, it will not start after warming up, and it will emit white smoke. Check whether there is water in the oil. If there is any water, turn off the fuel tank switch. Remove the fuel tank, open the switch, release the water, and close the switch until the diesel flows out. Remove the screw plug under the filter so that the diesel flows in the container. Then tighten the plug. If it is not the above reason and the fuel supply is good, you should check whether the fuel supply advance angle is appropriate.
1 The diesel engine is difficult to start and is inefficient. First of all, look at whether the fuel supply rod can reach the oil supply position. If not, the fault is the oil supply rod (or the rack rod) issuing the card and the starting oil supply is insufficient. If you can reach the start of the fuel supply position, you can start the diesel engine, and try to pinch the high pressure tubing and feel the pressure pulsation is obvious, if not obvious, the fault is the injection pump plunger wear parts, injection pump out valve The parts are not sealed or the spring is fatigued, broken, the injector needle valve parts wear; the needle valve cone and valve seat are not sealed, the injector spring is broken or improperly adjusted; if the pressure pulsation is obvious, it should be checked. The connection of the shaft and the timing of the oil supply meet the requirements. If it does not meet the requirements, the failure is the connection between the active flange plate of the coupling and the middle flange plate, the looseness of the active flange plate and the drive shaft, and the convexity of the drive shaft. The flange and driven shaft are loose, the driving claws and drive holes are loose, and the oil supply time is too early or too late. If the connection and fuel supply timing meet the requirements, you can check the quality of each cylinder's fuel injection to meet the requirements, if it does not meet the requirements, the fault is the injector needle valve wear or stuck parts, injector adjustment is not good The injector nozzle is blocked; if it meets the requirements, it is a failure of the non-fuel supply system.
2 The diesel engine started normally, but it was unable to operate. First, let the diesel engine run steadily at medium speed and observe whether the exhaust gas is white smoke. If it is white smoke, close the exhaust nozzle by hand and observe whether the palm is wet or even wet. If it is, the fault is in the cylinder. Or if there is water in the diesel; if not, the fault is too late. If it is not white smoke, you can observe whether it is black or gray smoke. If it is, remove the air filter and observe whether the black or gray smoke disappears. If it disappears, the fault is the air filter plug; if it does not disappear, then Faults include excessive oil circulation, poor diesel quality, wear of plunger parts, unsealable outlet valve parts, wear of needle valve parts, low injection pressure, poor spray quality, or drip oil. If it is not black or gray, then observe whether the blue smoke, if it is, then the fault is too much oil, oil bath type air filter plus too much oil, the cylinder on the engine oil.
The failure of the fuel supply system, which causes the diesel engine to run weak, is more complicated and complicated, and the diagnosed faults should be excluded. There are several ways to exclude.
1 All faults, such as broken pipes and plugged pipes diagnosed, loosening, falling off, hairpins, parts damage, and missing-loading, should be replaced, dredged, tightened, repaired, or adjusted according to specific conditions.
2 If there is air in the low-zhuang oil road, diagnose it immediately. The method is to fill the tank with oil first. If the seal of the oil circuit is good, first use the hand pump to supply oil, and then loosen the bleeder screw on the diesel filter to remove air until it flows out of the bleeder screw hole. The fuel does not contain air bubbles, then tighten the bleeder screw. In the same way, the air in the low pressure oil chamber of the injection pump is drained.
3 When it is diagnosed that there is moisture and air in the high-pressure oil circuit, remove the side cover of the fuel injection pump, loosen the joint of the high-pressure fuel pipe and the injector end so that the fuel supply pull rod is in the maximum oil supply position, while pumping oil with the hand oil pump The pump plungers of the injection pump are respectively shaken until the moisture and air in each high pressure oil line are exhausted. Finally, tighten the high pressure fuel pipe fitting and replace the fuel pump side cover.
4 Diagnosis When the fuel supply lever is started at a wrong position, the accelerator pedal should be depressed to the end, the operating arm of the fuel pump should be adjusted to the high speed limit screw, and the fuel supply lever must be adjusted to the rated fuel supply. The position moves a distance away from the refueling direction.
5 When there is a fault in the diagnosis of the fuel injection pump and injector, they should be removed and sent to the test bench for further inspection and calibration.
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