The maintenance technicians first used a professional diagnostic instrument to detect the injectors and found that the injection flow rate of the 0R-0471 injectors was only 65% of the standard value, and the injection pressure was unstable. After disassembling the injectors, it was observed that there was a large amount of carbon deposits and impurity deposits at the nozzle holes, which blocked the fuel injection channel. According to the on-site investigation, the construction site uses low-quality diesel fuel, and the fuel filter has not been replaced for a long time, resulting in impurities and colloids in the fuel entering the injectors, gradually forming deposits and blocking the nozzles. In addition, the excavators have been working continuously in high-temperature and dusty environments for a long time, which also accelerates the carbon deposition of the injectors.