Model: Hitachi ZX250LC-3
Factory time: 2011
Use time: 5800 hours
Location: Lanzhou, Gansu
Cause analysis:
The fault may be in low pressure oil circuit, fuel injection pump common rail system, injector and so on.
The Hitachi ZX250-3 excavator is stalling and even flameout maintenance during its work.
1. After replacing the fuel injector, the fault is still in use. Cylinder test is done by broken cylinder method, and fuel injector is supplied normally.
2, check the low pressure oil road, normal;
3, remove the injection pump to the end of the tubing of the common rail, plug the tubing outlet and start the diesel engine with hands. The finger can feel the pressure obviously. After pulling out the SCV valve (ignition timing adjustment valve), the injection height is about 6cm, and the injection pump is normal.
4. When the diesel engine is running at high speed, the common rail pressure is 71MPa. When the working device operates, the speed decreases sharply and the common rail pressure does not rise, which indicates that the pressure limiter is defective.
5. The pressure limiter is checked with our self-made overflow hollow bolt, and it is found that the pressure limiter has a large amount of fuel leaking out after starting, so it is concluded that the element has been damaged.
6. Under the highest speed of diesel engine and double pump overflow condition, the common rail pressure should reach 152MPa, and there is no leakage of fuel. The pressure limiter pressure of the existing fault is only 71MPa, and there is a lot of fuel leakage.
7. After the pressure limiter is replaced, the test machine is normal.
