Solutions for difficulties in starting a loader

A cat988 wheel loader, after routine maintenance, had difficulty starting up just 7 hours after startup when it was shut down. After a comprehensive inspection, it was found that there was residual air in the pipeline. So, the oil transfer pump, the return oil back pressure valve beside the ecm electronic control box, the fuel injector, etc. were disassembled and inspected. The results showed that there were no faults. Finally, the fuel supply system was inspected and it was found that the residual air in the system caused air resistance. There was not enough return oil to open the back pressure valve, which led to the malfunction. The fuel supply route of this machine was studied (fuel tank → primary filter → fuel pump → secondary filter → back pressure valve →ecm control box → fuel injector → back pressure valve; After the original manual pump was installed on the primary filter, to increase the fuel supply pressure, it was decided to install a manual pump on the upper seat of the secondary fuel filter element. As the original design reserved installation seat holes on the filter element seat, the installation was simple and easy. By simultaneously pumping oil with two-stage manual pumps, the air in the section from the ecm to the fuel injector is discharged. Then, in conjunction with the oil transfer pump, the system oil pressure is re-established and the motor is started. After venting twice and starting the engine for about 10 seconds, the engine ignited smoothly, indicating that the fault had been eliminated.