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一台ZX250-3型挖掘机配套的五十铃电喷柴油机,空转时正常,但工作时失速严重,甚至熄火,监控器一直有报警。故障可能在低压油路、喷油泵燃油共轨系统、喷油器等部位。更换喷油器后故障依旧;用断缸法逐缸测试,喷油器供油正常;检查低压油路,正常;拆下喷油泵至共轨的油管末端,用手堵住油管出口并启动柴油机,手指能明显地感觉到有压力,拔下SCV阀(点火正时调整阀)后,喷油高度约为6 cm,可见喷油泵正常。柴油机高速空转时共轨压力为71 MPa,工作装置动作时转速急剧下降,共轨压力不上升,说明压力限制器存在故障。
A ZX250-3 excavator supporting Isuzu EFI diesel engine, idling when normal, but the work of stalling serious, or even turn off the monitor has been alarm. Failure may be low pressure oil, fuel injection pump common rail system, fuel injectors and other parts. Replace the injector after the fault still; cylinder cylinder test by broken cylinder method, the fuel injector normal; check the low-pressure oil, normal; remove the fuel pump to the common rail end of the pipe, hand blocked the export of tubing and start the diesel engine , Fingers can obviously feel pressure, unplug the SCV valve (ignition timing adjustment valve), the fuel injection height of about 6 cm, we can see the normal injection pump. When the diesel engine idles at high speed, the common rail pressure is 71 MPa, the working speed of the working unit drops sharply and the pressure of the common rail does not rise, indicating that the pressure limiter is faulty.