A Fengshen blue bird car (using E-HU13 engine), the refrigerator is starting normal, but after a period of time to turn the engine out of the engine, it will be difficult to start, and the car has recently felt a significant increase in fuel consumption. First test the car to verify the failure phenomenon. In the condition of the refrigerator, the engine starts the engine smoothly, but the engine is jitter at idle speed, the exhaust pipe has a "sudden" sound, and the exhaust pipe can smell a strong smell of gasoline, and the exhaust pipe is smoked when the engine accelerates quickly. After the engine reaches its normal working temperature, the engine is restarted and the engine is started by multiple engines. According to the inspection results, it was preliminarily determined that the fault was caused by excessive mixture. First, tail gas analyzer was used to measure the tail gas. The content of HC was (440~450) x 10, and the content of CO was 6.3% ~ 8.2%. The signal voltage of the oxygen sensor is measured at 0.65 V~0.85 V, which proves that the mixture is indeed too thick. Then read the fault code, without fault code storage. Analysis can cause the cause of excessive mixture gas, there are the following possible: first, the air flow sensor signal misalignment; two is the throttle position sensor output signal error; three is the coolant temperature sensor fault; four is the injector leakage; five is the fuel system pressure is too high; six is the ECU fault. First, the air flow sensor is detected. The signal voltage is L.1 V at idle speed. With the increase of engine speed, the maximum voltage can reach 4.7 V. When measuring the throttle position sensor, the signal voltage increases with the increase of throttle opening. The resistance of the coolant temperature sensor is checked with the temperature of the engine at that time, but it is found that the wire side connector of the sensor is slightly rusted, so the corroded connector terminal is grind and then fasten firmly. Then, the ultrasonic cleaner is used to clean the injector, and then it is tested on the test bench, and the injector work is also in line with the requirements. Measuring fuel system pressure, engine idle speed is 290 kPa, slightly slightly high (normal about 250 kPa), but also in the normal range. It was no good to check this feeling, so we had to analyze the test data again, and found that except for the high pressure of the fuel system, the other data were normal, but the fuel pressure regulator was mainly regulated by the fuel pressure regulator. Then the vacuum pump was connected to the vacuum tube of the fuel pressure regulator, and it was found that no vacuum was formed over the pressure regulator, indicating that the diaphragm was damaged. The ignition switch was connected and the existing gasoline was sent from the fuel pressure regulator when the vacuum tube was not inserted into the fuel pressure regulator. The vacuum tube interface is ejected. It seems that the cause of the failure is here. As the fuel pressure regulator diaphragm is damaged, the oil recovery pressure is too high or no oil is returned. The gasoline directly enters the intake pipe from the vacuum tube on the fuel pressure regulator, resulting in the excessive concentration of the mixture. After the replacement of the fuel pressure regulator, the above fault is completely eliminated.