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A TOYOTA km 2008, with a mileage of about 184 thousand, and an engine type of 2GR-FE. The car was overhauled in the factory because of the rapid acceleration of weakness. According to the driver, it is only in the rapid acceleration of the vehicle to accelerate the failure phenomenon, even there have been 2 rapid acceleration of the situation, before the failure in the maintenance point to clean the throttle valve and injector, but the failure is still. After the car: test the fault, slowly step down the accelerator pedal, the speed can rise steadily, it seems that there is no abnormal; but when stepping on the accelerator pedal trying to overtake, it can obviously feel the acceleration of weakness, the fault does exist. Connecting the fault detector and reading the idle speed data flow, it is found that the voltage of the air fuel ratio sensor is 3.25 V, the short-term fuel correction value is 12.5%, the long-term fuel correction value is 19.5% (the standard should be 5% of soil), which indicates that the engine is in the state of excessive mixture gas for a long time. As a result of the acceleration of the accelerator pedal only to accelerate the acceleration of the phenomenon, so do the automatic transmission D stall test, the speed of stall is about 1800 r/min, normal should be about 2600 r/min. The reason why the stall speed of D is low is that the engine power is insufficient and the one-way clutch is not working well. Taking into account the slow acceleration of the vehicle running normally, and check the automatic transmission oil, is also normal. The possibility of eliminating the fault of the automatic transmission is preliminarily eliminated. According to the analysis of the failure phenomenon and the above inspection results, it is believed that the cause of the engine's rapid acceleration, weakness or even extinguishing should be the excessive mixture of gas, and the reason for the excessive mixture of gas may be the blockage of the injector, the low fuel pressure, the air leakage of the intake system, the damage of the carbon tank electromagnetic valve, the damage of the air flow sensor and the air fuel ratio sensor. Barrier and so on. The car has previously cleaned the throttle valve and the injector, so the key inspection of the various intake pipes, no abnormal; check the carbon tank solenoid valve, it is not guided when closed; the fuel injection quantity of the engine is tested actively, the air fuel ratio sensor can feed back the voltage signal normally, the voltage is 2.94 V when the injection amount is large, and the amount of fuel injection is more than that of the fuel injection. The hourly voltage was 4.31 V; then the air flow sensor was replaced, but the fault remained. In this case, only the fuel pressure is not checked, the fuel pressure gauge is checked, the fuel pressure is about 200 kPa at idle speed, the accelerator pedal is slowly stepped down, the fuel pressure is rising normally, the accelerator pedal is stepped on, the fuel pressure drops to 150 kPa instantaneously, which is obviously abnormal. Referring to relevant information, it is known that the speed of the fuel pump is low and high speed control. In order to judge whether the fuel pump relay and engine control is a problem, the engine is still running at low speed under the condition of heavy load, resulting in the drop of fuel pressure. The maintenance personnel short the fuel pump resistor to make the fuel pump run at a high speed. At this time the fuel pressure gauge is shown to be 300 kPa. However, when the accelerator pedal is accelerated, the fuel pressure fluctuates dramatically, sometimes can reach 350 kPa, sometimes down to about 250 kPa, indicating that the fuel pressure is still abnormal, which is also indirectly excluded. The possibility of problems existing in fuel pump relay and engine control. According to the above test results, the cause of the fault is that the power supply voltage of the fuel pump is unstable or the fuel pressure regulator is defective. First check the line of the fuel pump, measure the power supply and the grounding of the fuel pump. The power supply voltage of the fuel pump is 12V, normal. Then measure the resistance of the fuel pump to 3.2 ohms, which is also within the normal range (normally 0.2 to 3.4 ohms). So remove the fuel filter and check the fuel pressure regulator. However, during the process of removing the fuel filter, it was found that the terminals of the extension connector of the fuel pump wiring harness were corroded, and the reeds had been disconnected. It is suspected that the corrosion of the connector leads to poor line contact and unstable supply voltage, resulting in abnormal fuel pressure. Troubleshooting: replace the fuel pump harness and the fuel filter after commissioning, troubleshooting. Summary: corrosion connector is immersed in fuel for a long time. Why is it corroded? After asking the driver, the car had previously added ethanol gasoline in the field, and suspected that it contained more moisture in the gasoline, leading to corrosion of terminals.