故障现象一辆苏州金龙KLQ6109Q客车,装用玉柴YC6G270-20发动机,行驶里程为40万km。驾驶人反映该车发动机不能熄火,需要手推柴油泵停油手柄才能熄火,之前更换过熄火断油气缸和熄火继电器,但故障依旧。故障诊断该发动机熄火装置由点火开关、熄火继电器、后熄火开关、熄火控制器和熄火断油气缸等部分组成,其工作原理如图1所示。该发动机熄火装置具有以下特点。(1)通电熄火。熄火断油气缸是电磁阀 Fault phenomenon A Suzhou Jinlong KLQ6109Q bus, equipped with Yuchai YC6G270-20 engine mileage of 40 million km. The driver said the car engine can not turn off, you need to hand push the diesel pump to stop the flameout handle, before replacing the flameout cylinder and flameout relay, but the fault still. Fault diagnosis The engine flameout device by the ignition switch, turn off the relay, turn off the switch, turn off the controller and turn off the fuel tank and other components, the working principle shown in Figure 1. The engine flameout has the following features. (1) Turn off the power. Flameout cylinder is a solenoid valve