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Stuck Fault of Fuel Injection Pump in Diesel Generator Set

Dec. 11, 2023

The fuel injection pump is the "heart" of a diesel generator set, and its performance directly affects the power and economy of the diesel engine. If the diesel engine experiences malfunctions such as running, speeding, or inability to increase speed, there is often a problem of fuel injection pump jamming. How to determine the stuck part of the fuel injection pump is the key to troubleshooting. The following steps can be taken.


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1. Place the throttle lever in the maximum fuel supply position, rotate the crankshaft, and you should be able to hear the sound of fuel injection in the cylinder. Then place the throttle lever in the position where the fuel supply is stopped, and there should be no sound of fuel injection when turning the crankshaft. If the fuel injection sound can be heard or not heard in both extreme positions, it indicates that the fuel supply rod is stuck.


For diesel generators with foot throttle, you can start the diesel engine and repeatedly and quickly press and lift the accelerator pedal to check. When the accelerator pedal is quickly lifted, if the speed of the diesel engine continues to increase, it may be due to the plunger or lever being stuck. If the diesel engine stalls, it indicates a malfunction in the governor. If the pedal does not return, it is mostly due to jamming at the accelerator pedal lever and other places. If the pull rod is stuck, you can first use a special tool to pry and remove the rust around the pull rod and its hole, so that the pull rod can move left and right. If it is stuck tightly, check the oil pump.


2. Remove the inspection window of the fuel injection pump and check the tightness of the engagement between the gear rod and the fan-shaped teeth, or the plunger adjustment arm and the oil quantity adjustment fork. If used for purposes that cannot move left or right or can only move within a small range, it may be due to deformation, rust, or foreign objects getting stuck on the gear rod. At this point, the plunger pump gear rod can be separated from the governor rod. If the gear rod slides freely, it indicates that it is stuck inside the governor. If the gear rod cannot move and it is still difficult to move after disconnecting the speed controller, it indicates that the jamming is occurring inside the plunger pump.


You can also move the gear rod left and right while slowly rotating the crankshaft to make the plunger of each cylinder move up and down, and check if the gear rod is stuck during the movement. When the toothed rod is felt to be tight, immediately stop rotating the diesel engine, and then use a special tool to gently move the plunger rotation arm one by one. If the plunger of a certain cylinder is felt to be stuck, the fault may be on the plunger pair. Then use special tools to pry each plunger up and down. If a plunger cannot be pried, it indicates that the plunger pair is faulty.


3. Loosen the plunger limit screw and continue the test according to the above method. If it can be rotated, it indicates that the top of the limit screw is blocking the plunger sleeve, causing deformation of the plunger sleeve. This screw should be removed, the thickness of the copper washer should be increased appropriately, and then the limit screw should be tightened.


4. If the plunger sleeve limit screw is loosened and the plunger still cannot be turned, the oil outlet valve seat can be loosened. If it can rotate at this time, it indicates that the pressure seat of the oil outlet valve has been tightened excessively, causing deformation of the plunger sleeve. The gasket of the pressure seat between the oil outlets should be checked, and the tightening torque should be adjusted to the value specified in the user manual.


5. If the pressure seat of the oil valve is still stuck after loosening, the fuel injection pump should be disassembled for inspection. If the clearance between the plunger sleeve and the oil pump housing is too small, the shoulder is uneven, or there is dirt, it should be cleaned, leveled, or replaced. If impurities enter the mating surface due to unclean diesel, and the working surface of the head is pulled, a new plunger pair should generally be replaced. If there is only a slight strain on the lower part, it can be repaired by grinding.


As a professional diesel generator manufacturer, we always insist on using first-class talents to build a first-class enterprise, create first-class products, create first-class services, and strive to build a first-class domestic enterprise. If you would like to get more information welcome to contact us via sales@dieselgeneratortech.com.

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