When the plunger of the fuel injection pump is stuck, it will affect the normal operation of the governor and easily cause the engine to run faster. If not dealt with in a timely manner, it will cause serious accidents.  
　　1、 The plunger is bent. Due to carelessness during transportation, storage, and assembly of the plunger pair, the plunger may slightly bend and become stuck during operation. In such cases, it should be replaced promptly.  
　　2、 The plunger is scratched due to collision with hair. Due to incomplete cleaning of the plunger during assembly, or impurities entering between the plunger pairs, careless assembly may cause the plunger to scratch and become stuck. So, during assembly, careful installation should be carried out to avoid damaging the plunger, and the plunger pair components should be cleaned thoroughly to prevent impurities from entering between the plunger pairs.  
　　3、 The sleeve positioning screw is too long. If the positioning screw of the plunger sleeve is too long or the washer is forgotten to be installed when installing the positioning screw, the sleeve will be stuck, causing the sleeve to deviate and the plunger to become stuck. If the positioning screw is too long, it can be filed short appropriately. When installing the positioning screw, do not forget to install the washer.  
　　4、 The pump body base is uneven. Due to the uneven or contaminated base at the shoulder of the plunger sleeve installed on the pump body, the assembly accuracy of the sleeve is affected, causing the plunger assembly of the oil pump to deviate and resulting in the plunger getting stuck. The method to check the unevenness of the pump body is to pull down the fuel injection pump from the body, connect the low-pressure oil circuit, and turn on the fuel tank switch to fill the pump body with diesel, and clean the outside of the fuel injection pump. If oil leakage is found at the roller, it indicates that the pump body base is uneven, causing diesel leakage. An old plunger sleeve can be used, and a grinding sand can be applied to the shoulder and installed into the pump body. The sleeve should be continuously rotated and tapped for grinding. After grinding, it should be reinstalled and checked for oil leakage.  
　　5、 The storage time of the new plunger pair is too long. Long storage time of new plunger pairs can easily cause oil loss and oxidation reactions, leading to rusting of the plunger. Assembly without cleaning can cause the plunger to become stuck during operation. In this case, immerse the plunger pair in kerosene or diesel for a period of time, then rotate and repeatedly pull the plunger to grind them together until the plunger pair rotates flexibly and is carefully cleaned before assembly and use.