Technical Consultation
1. The starter cannot drive the diesel engine
Phenomenon: When the starter switch is turned on, the starter will not run or idle.
Cause: starting system failure; The engine is stuck inside; Clutch or transmission is stuck; The starter gear and flywheel ring gear are stuck.
2. The starter can drive the diesel engine to run, but there is no sign of starting
Phenomenon 1:
Loosen the vent plug of the fuel injection pump and pump the oil with the hand pump. There is no oil at the vent plug or only foam diesel is left for a long time.
Cause: Generally, this phenomenon can be determined as low pressure oil circuit failure. Possible causes: no oil in the oil tank, the oil tank switch is not opened, or the vent hole of the oil tank cover is blocked; Oil pipe (oil suction pipe) is blocked or leaks air; The filter element is blocked; The filter screen of oil transfer pump is blocked; The fuel transfer pump does not work well; The pressure reducing valve fails, reducing the oil pressure in the low-pressure oil chamber; The oil circuit is frozen and blocked in winter; The diesel oil used in winter is not of the correct brand, and paraffin wax is separated after condensation, resulting in blockage of the oil circuit.
Phenomenon 2:
The low-pressure oil circuit is normal, but the fuel injectors of each cylinder do not inject fuel.
Cause: In general, this phenomenon can be determined as high-pressure oil circuit failure. ① Fuel injection pump failure. The connecting key between the driving plate and the passive plate of the coupling is damaged; The clearance between tappet and plunger foot and the clearance between plunger and sleeve are too large; The plunger stops at the position without oil supply due to the clamping of the rack or other reasons; The outlet valve is not sealed, stuck or the spring is broken; The failure of the pressure limiting valve causes insufficient oil pressure in the low-pressure chamber. ② Fuel injector failure. Namely, the injection hole is blocked, and the needle valve cannot be opened due to carbon deposition or sintering; The injection pressure is adjusted too high. ③ There is air in the high-pressure oil circuit; The high-pressure oil pipe is broken or the connector is loose.
3. The starter can drive the diesel engine to run, exhaust smoke from the exhaust pipe, but cannot get on the vehicle
Phenomenon 1:
The exhaust pipe emits black smoke and cannot land the vehicle.
Cause: air inlet is blocked; The fuel injection timing is seriously out of order; Insufficient injection pressure, poor atomization, low cylinder pressure, poor diesel quality, etc.
In this case, there are several diagnostic methods to choose:
① Check whether the air inlet and exhaust pipes are unblocked, such as whether the air filter is blocked and whether the exhaust brake valve is fully opened;
② Check whether the fuel supply advance angle meets the requirements;
③ Check the technical condition of the fuel injector;
④ If the oil supply system works normally, check the cylinder pressure. The cause of insufficient pressure shall be found from the valve, piston ring, cylinder gasket, cylinder sleeve, etc.
Phenomenon 2:
White smoke from exhaust pipe cannot be started.
Cause: water in diesel; The engine temperature is too low (the low-temperature starting preheating device fails); Incorrect fuel injection timing (usually too late); Insufficient air or oil supply; Poor injection quality of fuel injector; Insufficient cylinder pressure.
The following diagnosis and treatment methods can be adopted for such faults:
① First approach the outlet of the muffler of the exhaust pipe by hand. If water drops on your hands after the white smoke, it means that there is water entering the combustion chamber. Check the diesel quality and whether the oil level of the oil pan rises. If the oil level rises, further find out the water leakage part;
② If the oil supply is in good condition and the engine cannot be started due to "popping" noise, check whether the preheating device is in good condition and whether the oil supply timing is accurate. If not, adjust it;
③ If the above items are normal, check whether the valve foot clearance, fuel injection quality and cylinder pressure are appropriate.
