The maintenance technicians first checked the fuel supply system and found that the fuel pump was working normally, and the fuel pressure was within the standard range. After disassembling the 0R-0471 injectors, it was found that the internal fuel channel was completely blocked by colloidal substances and impurities, and the fuel could not pass through the channel to the nozzle, resulting in no injection. The reason for the blockage was that the bulldozer had been parked for a long time, and the diesel fuel in the injectors had deteriorated and produced colloids, which blocked the fuel channel.