Common Faults and Solutions of Fuel System of Generator Set

The fuel system of diesel generator set is the main core part. In addition to the early wear of the three precision coupling parts of the fuel system, which leads to the reduction of generator power, increase of fuel consumption and exhaust smoke, there are two types of faults most likely to occur in the fuel system: one is the fault caused by improper installation of fuel injection pump, and the other is the fault in use.

A.Failure caused by improper installation of fuel injection pump of diesel generator set

1. The semicircular key is not installed in place

For the fuel injection pump connected by flange, when the installation position of the semicircular key between the fuel supply timing gear and the automatic regulator of fuel supply advance angle and the camshaft of the fuel injection pump is incorrect, there will be fuel supply timing misalignment, difficult engine start, smoke and high water temperature. If it cannot be adjusted through the arc hole on the flange, the fuel injection pump needs to be removed and reinstalled. After removal, obvious indentation can be observed on the semicircular key.

2. The oil inlet and return screws are installed incorrectly

When connecting the oil pipe, if the oil return screw is wrongly installed on the oil inlet pipe joint of the fuel injection pump, due to the action of the check valve in the oil return screw, the fuel cannot enter or only a small amount enters the oil inlet chamber of the fuel injection pump, so that the diesel generator set cannot be started or cannot be refueled after starting to increase the speed. At this time, the hand pump has great resistance to pump oil, and even cannot press the hand pump. At this time, the fault can be eliminated as long as the installation positions of the oil inlet and return screws are exchanged.

B.Common faults in the use of diesel generator set

1. Poor oil supply of low-pressure oil circuit

The oil inlet and return pipelines of the diesel generator set from the oil tank to the oil inlet chamber of the fuel injection pump belong to the low-pressure oil circuit. When the pipeline joint, gasket and oil pipe leak oil due to damage, the air will enter the oil circuit to produce air resistance, resulting in poor oil supply, difficult engine start, slow acceleration and other faults, and will automatically shut down in serious cases. When the cross-sectional area of the oil pipe is reduced due to aging, deformation and impurity blockage, or the oil filter screen and diesel filter element are blocked due to oil pollution, it will cause insufficient oil supply and reduce the power of the engine and make it difficult to start. Pump the oil to a certain pressure by hand pump and loosen the vent screw. If there are bubbles overflowing and the exhaust is not complete all the time, it means that the oil circuit is filled with air. If there are no bubbles, but diesel oil overflows from the bleeder screw, the oil circuit is blocked. The normal phenomenon is to slightly loosen the open air screw and immediately spray out the oil column with a certain pressure. The troubleshooting method is to find out the damaged or aging gasket, joint or oil pipe and replace it. The way to prevent such faults is to clean the oil inlet filter screen and diesel filter element frequently, check the pipeline frequently, and solve the problems in time when they are found.

2. The oil delivery pump piston is broken

The diesel generator set suddenly stalls during operation and cannot be started. Loosen the bleed screw and check that if there is no or little fuel in the low-pressure oil chamber of the fuel injection pump, pump the oil with the hand pump until the whole low-pressure oil chamber is filled with oil, exhaust the air and restart the engine. The engine returns to normal, but it will automatically shut down again after driving for a certain distance. This fault phenomenon is likely to be that the piston spring of the oil transfer pump is broken. This fault can be eliminated directly. Unscrew the screw and replace the spring.

3. The check valve of the oil transfer pump is not tightly sealed

The diesel generator set works normally after startup, but it is difficult to start after flameout for a certain time. There is bubble overflow when loosening the vent screw. It can be started only after the air is drained again. This fault is mostly caused by the loose sealing of the check valve of the oil transfer pump. The inspection method is to unscrew the oil outlet screw of the oil delivery pump and pump the oil pump to fill the oil cavity of the oil outlet joint. If the oil level in the joint drops quickly, it indicates that the check valve is not sealed well. Remove the check valve and check whether the seal is intact, whether the check valve spring is broken or deformed, and whether there are particulate impurities on the sealing seat surface. According to the specific situation, grind the sealing surface and replace the check valve or check valve spring to eliminate the fault. Normally, the oil level does not drop within more than 3 minutes, and the oil column of the pump is strongly ejected from the oil outlet joint.

4. High pressure oil pipe blocked

When the high-pressure oil pipe of a cylinder is blocked due to deformation or impurities, there may be an obvious knocking sound at the oil pipe after starting Yuchai diesel generators, and the power of the diesel generator set decreases because the cylinder cannot work normally. The inspection method is to loosen the nut at the oil inlet end of the high-pressure oil pipe cylinder by cylinder. When the knocking sound disappears after loosening a cylinder, it can be concluded that the cylinder is a faulty cylinder, and the fault can be eliminated after replacing the oil pipe.

5. Fuel injector coupling stuck

When the injector needle valve is stuck in the closed position, there is a regular knocking sound near the cylinder head. It is caused by the impact of the pressure wave of the fuel injection pump on the fuel injector. The judgment method is to loosen the high-pressure oil pipe connected to the injector end. If the knocking sound disappears immediately, it can be concluded that the needle valve of the injector of this cylinder is stuck.