Nowadays, most bulldozers use Weichai series National III diesel engines. The structure of the fuel supply system is quite different from National II diesel engines, and the maintenance methods are also different. The following is the normal operation of Weichai Guosan diesel engine starter, the diesel engine cannot start, and the exhaust pipe is smokeless. Check the instrument, the fault code shows the cause of the fault such as rail pressure lower than the normal value and the troubleshooting method.

1: Check whether the fuel level in the fuel tank is too low, and then check whether the fuel filter electric pump can work normally, if it works poorly, the diesel cannot reach the fuel transfer pump.

2: Check whether there is air in the low-pressure oil circuit and exhaust air.

The exhaust method is to turn the key switch to ON, turn on the fuel filter electric pump switch, the electric pump pumps oil, and the air in the low-pressure oil circuit system is automatically discharged. You can also open the bleed screw plug on the fine filter to allow the fuel filter electric pump to pump oil. When oil flows out from the bleed screw plug, close the bleed screw plug to complete the exhaust.

If the diesel engine cannot be started even after the air in the low-pressure oil circuit is drained, it is judged that there is air in the high-pressure oil circuit and the air in the high-pressure oil circuit needs to be discharged. The exhaust method is to loosen the high-pressure oil pipe of a certain cylinder, and use the starter to drive the diesel engine to run until the high-pressure oil pipe continues to discharge oil (it is recommended not to remove the high-pressure oil pipe joint frequently). If the engine cannot be started after exhausting, check the high-pressure oil circuit for leakage. If the high and low oil circuits do not leak, check whether the diesel filter is blocked. It is recommended to replace the diesel filter in time.

3: If no fault is found in the above inspections, check whether the initial voltage value of the rail pressure sensor is about 500mV, or whether the set rail pressure is 30～50MPa, if the pressure is abnormal, check whether the connector is firmly inserted. If there is no voltage or rail pressure inspection equipment, you can also unplug the rail pressure sensor and metering unit and start the diesel engine to check whether it is in good condition. Unplugging is the default state, the diesel engine default rail pressure sensor and metering unit status is activated, and the fuel will be supplied to the common rail pipe with the maximum fuel supply. If the rail pressure cannot be established, it means that the rail pressure sensor and metering unit are not faulty .

4: Check the diesel engine fuel system item by item according to the above inspection process. When the high-pressure fuel pipe is disassembled and the diesel engine is driven by the starter, no oil is found to flow out of the high-pressure fuel pipe. Disconnect the flow metering valve connector, and run the diesel engine again, but there is still no oil flowing out, which can determine the high-pressure pump failure. After replacing the new high-pressure pump and exhausting the fuel system air, start the diesel engine, the diesel engine can start normally, and the fault can be eliminated.