The fuel injector often does not inject fuel. At this time, you should visually inspect the fuel injector and remove the fuel injector. If there is a special calibration device for the fuel injector, you can move the fuel injector. Set the calibration station to perform calibration according to technical requirements. When there is no special calibration equipment for fuel injectors, you can test on the vehicle. The specific method is:
　　 Remove the fuel injector and connect the nozzle to the high-pressure fuel pipe, then start the engine to make the fuel injection pump work, and observe whether the fuel injector is injecting fuel. If you do not inject oil, you can use a screwdriver to gradually unscrew the pressure regulating screw on the fuel injector to gradually reduce the pre-tightening force of the pressure regulating spring. At this time, observe the fuel injection effect. If the fuel injection is good, it means that the pressure regulating spring is adjusted. The fixed pressure is too high, or the fuel injection pump supply pressure is too low.
　　 If the pressure-regulating spring still does not spray after the elastic force is reduced, it proves that the needle valve is stuck in the closed position or the spray hole is blocked by carbon deposits, and the cause should continue to be investigated and eliminated in a targeted manner. When adjusting the injector pressure on the vehicle, the method is the same as the above, but after the injector pressure is adjusted, compare it with other injectors with good fuel injection. After the adjustment, lock the lock nut.