The maintenance technicians used a professional pressure tester to detect the 0R-3002 injectors and found that the injection pressure dropped from the standard 19-21MPa to 15MPa, which was far below the normal range. After disassembling the injectors, it was found that the internal plunger and cylinder sleeve of the injectors were severely worn, resulting in poor sealing and pressure drop. The reason for the wear was that the fuel filter was not replaced regularly, and the impurities in the fuel entered the injectors, causing abrasive wear of the plunger and cylinder sleeve.