A 2008 km 0.8 L car with a mileage of about 40 thousand 372Q. User response: when starting the vehicle, the starter can drive the engine to turn, but there is no sign of the car. After receiving the vehicle: pull off the high voltage line for jumping fire test, there is a high pressure fire, indicating that the ignition system is normal. Unplug the fuel injection line of the injector oil rail and start the engine. There is no fuel flow in the tubing, and the fuel supply system is initially judged to be defective. Check the related lines of the fuel supply system: check the fuel pump fuse F23 in the fuse box, normal; find the fuel pump relay in the fuse box, start the engine with the hand touch the relay and do not feel the relay action; remove the rear seat, find the fuel pump and pull the plug to start. Check the power supply with the test lamp at the same time. The result is that the test lamp is not lighted, which indicates the fault is on the control circuit of the fuel pump. Fuse F6 was found in the fuse box of the engine compartment. When it was removed, it was found that it had fused. Replace the fuse, test the car, the fault is completely eliminated. According to the circuit diagram of the fuel supply system, the control circuit of the fuel pump relay is as follows: battery power supply. Main relay: fuel pump relay and engine control unit. Earthing. When the engine is starting, the engine control unit receives the engine speed signal, the control end of the fuel pump relay is grounded, the fuel pump relay is absorbed, and the fuel pump gets the power after the power supply. The main point of overhaul work is to measure the terminals of the fuel pump relay one by one with the test lights, and then locate the fault parts according to the working conditions of the terminals and troubleshoot them.