Diesel Generator Weak Operation

Jul. 23, 2022

Diesel generators run weakly and emit heavy smoke. This is mainly due to insufficient fuel injection atomization and incorrect refueling time.

1. The fuel injection nozzle or the fuel delivery valve is  severely worn, dripping, poor atomization, and insufficient combustion.

2. The installation position of the fuel injector on the cylinder head is not correct. The use of copper pads or aluminum washers that are too thick or too thin may cause improper injection of the fuel injector and insufficient combustion.

3. The components of the fuel injection pump transmission system are worn out, causing the fuel supply to be too late.

4.The fuel supply time has not been adjusted.

 300kw generator

A. When the speed is unstable, the diesel engine emits smoke.


The fuel supply of different cylinders is inconsistent. The abrasion or improper adjustment of the jet pump and fuel injection nozzle can easily cause uneven fuel supply in each cylinder. The method of judging the inconsistency of fuel supply can make the diesel generator run empty. Using the cylinder stop method, one cylinder is stopped for oil supply in turn, and the speed meter is used to measure the speed. When the cylinder is broken, the fuel supply of each cylinder is the same, and the change of the cut-off volume should be the same or very close. If there is a big difference in the speed change, the fuel supply of the fuel injection pump should be adjusted.


Water vapor or air leakage in the oil circuit of the diesel fuel supply system can also cause poor fuel supply from the fuel injection pump.


B. Diesel generators have low speed and smoke, but the high speed is basically normal.

It's that the cylinder leaks air, and the air leaks less at high speeds, so it can basically work normally. Gas leakage causes low temperature and is not easy to cause fire. During the operation of the diesel genset generator, if a large amount of smoke is emitted from the fuel filler port, or there is a squeak air leakage sound in the crankshaft operation part, and it is obvious at low speed, it can be judged as air leakage between the cylinder block and the piston. The other two possible leaks are the valve and cylinder head gasket.

C. The diesel generator power is not good, but there is no smoke at the exhaust port when idling and when the fuel supply is small, and it is easy to emit black smoke when the fuel supply is large.

1. The air filter element is blocked, causing the diesel generator to enter poor water, but the power is not enough.

2. The valve clearance is too large, resulting in insufficient valve opening and poor air intake.

3. Too much carbon deposits in the exhaust pipe, and the exhaust port resistance is too large.

 Diesel Generator Weak Operation

Teach you how to identify the failure of weak starting and running of diesel generator.


When the diesel engine is started, the crankshaft does not rotate or rotates slowly, so that the diesel engine cannot enter the self running state. This kind of fault is mainly caused by insufficient battery power, excessive starting resistance or poor contact surface after the internal movable contact and static contact of the electromagnetic switch are burned. The inspection method is as follows.


1. Check whether the battery is sufficient.

2. Check the contact between the brush and the commutator. Under normal conditions, the contact surface between the bottom surface of the brush and the commutator should be more than 85%. If it does not meet the technical requirements, replace the brush with a new one.

3. Check whether the commutator is burned, worn, scratched, dented, etc. If there is much dirt on the surface of the commutator, clean it with diesel or gasoline. If there is serious burn, scratch and wear, resulting in the surface is not smooth or out of round, it can be repaired or replaced as appropriate. During repair, the commutator can be machined with a lathe and polished with a fine emery cloth.

4. Check the working surfaces of the movable contacts and the two fixed contacts inside the electromagnetic switch. If the movable contacts and the fixed contacts are burned, resulting in the inability of the starter to operate, the movable contacts and the fixed contacts can be ground flat with fine emery cloth.

Guangxi Dingbo Power Equipment Manufacturing Co., Ltd., founded in 2006, is a Chinese diesel generator brand OEM manufacturer integrating the design, supply, commissioning and maintenance of diesel generator sets, providing you with one-stop service for diesel generator sets. For more details about the generator, please call Dingbo Power or contact us online.

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