Diagnosis and Removal of Common Faults of Diesel Engine of Diesel Forklift

Oct 28, 2022

1. Diesel engine is not easy to start.

1. The exhaust pipe does not emit smoke. The reason for this problem is that the fuel injection pump is not supplying fuel.

Elimination methods are: pump oil with hand oil pump

A. Supply oil, check whether the adjustment gear rod of the fuel injection pump is stuck in the position where no oil is supplied;

B. If there is air, put clean air at the bleed screw of the fuel injection pump;

C. No fuel supply, the diesel fine filter is blocked, the spring of the fuel pump is broken, the check valve is not sealed, the fuel tank has no oil or the oil circuit switch is closed, and the fuel pipe from the fuel tank to the fuel pump is blocked or leaks;

D. When the piston rod of the hand oil pump is lifted, it feels suction, and when the hand is released, it will automatically return to the position, and the oil path between the oil tank and the oil pipe will be blocked;

E. It is laborious to press down the piston rod of the hand oil pump, which means that the diesel fine filter is blocked and should be disassembled and cleaned or replaced directly.


2. White smoke is emitted from the exhaust pipe. There are two reasons for this problem

A. Diesel oil is impregnated with water;

B. The fuel injection advance angle of the fuel injection pump is too late. Elimination methods are: remove the moisture in the oil; if it is too late, the diesel will not easily catch fire when the cylinder pressure and temperature drop, and it will be discharged from the exhaust pipe together with the air, which is milky white and should be adjusted in time.

3. The exhaust pipe emits thick smoke and the sound is messy. The reason for this problem is the confusion of fuel supply time.

Elimination methods are: when the fuel injection pump coupling is installed, the driven disc may be delayed a few degrees, and the fuel injection pump supplies oil at the top dead center of the cylinder piston. resulting in the engine not working.


Second, the diesel engine power is insufficient.

1. The fuel supply is small. Diagnosis and exclusion methods include:

A. When adjusting the fuel injection pump, because the temperature in the laboratory is too low or too high, although it is adjusted according to the technical specifications, it will appear that the fuel supply is insufficient when used on the oil disassembler. In this case, just adjust the fuel supply;

B. The plunger pair is worn and the oil supply is reduced, which can be appropriately reduced, or the oil supply can be appropriately increased. If the wear is serious, the plunger pair should be replaced and the fuel injection pump should be readjusted.

2. There is air in the oil cavity, which causes air resistance and reduces the oil supply.

Diagnosis and elimination methods are as follows: when the engine is working, loosen the fuel injection pump bleed screw one by one.

3. The oil delivery pump is insufficient. Diagnosis and elimination methods include: wear of the oil pump, blockage of the fine filter, failure of the oil return valve, etc., which will reduce the oil supply.

4. Sudden lack of power during operation. Diagnosis and elimination methods are as follows: it may be that the adjusting gear rod is stuck and cannot be moved to the maximum oil supply position; or the governor movement is stuck, the governor spring is broken, etc.

5, the acceleration response is not sensitive. Diagnosis and exclusion methods are: oil supply time is too early or too late.

3. The color of the exhaust smoke from the diesel engine is incorrect.

1. White smoke. Diagnosis and exclusion methods include:

A. If it is white smoke when the car starts cold in winter, if the smoke stops when the temperature rises, it is a normal phenomenon.

B. There is water in diesel oil, and white smoke like water vapor comes out.

C. The fuel supply time is too late, and some diesel fuels are not completely burned in the cylinder, and white smoke emerges from the exhaust pipe. The fuel supply advance angle should be increased.

2. Black smoke. Diagnosis and exclusion methods include:

A. The oil supply time is too early, the pressure and temperature in the cylinder are low, and some diesel fuels are not completely burned to form carbon particles, which are discharged from the exhaust pipe;

B. Poor atomization of fuel injection, resulting in oil droplets, which cannot be well mixed with air and incomplete combustion;

C. The air filter is blocked, the intake air is insufficient, the mixture is too rich, and the combustion is incomplete. If black smoke is emitted at high speed and low speed, the air filter can be removed. If the black smoke disappears immediately, it can be diagnosed that the air filter is blocked and should be cleaned or replaced directly;

D. The diesel engine emits black smoke under heavy load, which may be caused by the load of the forklift exceeding the allowable limit. Just reduce the load.

3. Blue smoke and odor. Diagnosis and elimination methods are as follows: due to the oil in the cylinder, or the oil level in the air filter is too high, the organic oil enters the cylinder and burns.

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