Isuzu engine troubleshooting method

- Jul 31, 2020-

Isuzu engine troubleshooting method

    Based on the above reasons, the troubleshooting steps are as follows:

     1. Firstly, start the search from the fuel supply system to find out whether gas has entered the fuel line of the fuel supply system to reduce the fuel supply of the fuel injection pump. After checking all the fuel lines from the fuel tank outlet pipe to the high pressure pump, no pipeline is found. The phenomenon of loosening or rupture of air leakage. In order to ensure that there is no air leakage in the pipeline, a new spare hand oil pump is used, and the method of "pumping a bottle" is used to directly supply fuel to the diesel pump without passing through the diesel low-pressure pipeline of the original car. The pipeline is good.

     2. Using the cylinder breaking method, loosen the high-pressure oil pipe in front of the injector in turn, check the combustion of each cylinder of the engine, and find that the reaction of each cylinder is not obvious. Remove the injector and calibrate the injector on the test bench. It is found that the injectors of each cylinder are poorly atomized and the dripping phenomenon is serious, so replace the injector and correct the injector injection pressure to match the injector The pressure required by the working standard is used to measure the pressure of each cylinder with a cylinder gauge. By detecting that the pressure of each cylinder is within the normal range, no cylinder pressure is too low. Installed the new injector after verification, and restarted the engine. It was found that the engine running condition improved slightly, but it still could not meet the working requirements. Since the connection between the timing gear and the high-pressure pump gear is not disassembled, and the engine malfunctions suddenly, the reason for the late ignition time can be eliminated.

     3. During the combustion process of the engine, there is no water spray in the exhaust pipe, no air bubbles or water return in the cooling water tank, and no shortage of coolant, which shows that the cylinder head gasket is not eroded.

     4. After the above steps of troubleshooting, it is suspected that the high-pressure pump is faulty. After the high-pressure pump was disassembled, the pump was commissioned to be externally calibrated. It was found that there was a lot of wear between the distributor rotor and the sleeve of the distributor pump, which caused the oil pressure to decrease and the oil supply of the oil pump to reduce. Therefore, the distribution rotor assembly was replaced, and all the fuel injection indicators were found to be qualified on the test bench. After the vehicle was installed, the engine was started again, and the engine still couldn't speed up and emit white smoke. Open the timing gear chamber cover and check that the fuel supply timing has not changed. Once again, the high-pressure pump was removed and tested on the test bench. It was found that all indicators of the high-pressure pump were qualified.

     5. After replacing the high-pressure pump of another normal Isuzu engine of the same model with this car, start the engine, the exhaust pipe no longer emits white smoke, the refueling speed rises rapidly, and the operation is strong. Therefore, it is confirmed that the high-pressure pump of the original car is still faulty after the correction. Then the high-pressure pump was completely disassembled and cleaned carefully. It was found that the oil supply port in front of the distribution pump rotor was blocked by gelatinous impurities, which hindered the normal supply of the distribution pump. In the early stage of pump calibration on the pump test bench, the oil transfer pump used for the adjustment test was not exactly the same as the actual one, especially the passage capacity and the degree of oil leakage of the valve mount and the oil pipe were different. The high-pressure pump failed in actual work. After recalibration, the high-pressure pump was assembled to the engine, and the fault was completely resolved.