A 2005 km TOYOTA corolla car with a mileage of about 138 thousand 1ZZ. Customer response: after the vehicle has been put out for a period of time, it can not start for the first time, and it needs to be repeated two or three times to succeed. Malfunction analysis: according to the customer's opinion, the vehicle will be placed more than 20min, and it is not possible to start the vehicle at once. The vehicle can be started two or three times in a row. The cause of this fault is probably fuel oil pressure or poor ignition system. First check vehicle fuel pressure, install fuel pressure gauge to test fuel pressure, start engine fuel pressure value is 320kPa, normal. After quenching, the fuel pressure slowly drops to 0kPa. The leakage is too fast and no oil pressure is maintained. It is suspected that the gasoline pressure regulating valve is faulty and the oil pressure test is made after changing the fuel pressure regulator. After starting the engine, the fuel pressure value is 320kPa. When the fuel pressure drops to about 200kPa after quenching, the engine will not stop. Troubleshooting: solve the problem after changing the gasoline pressure regulating valve. Fault revelation: reasonable use of tools can solve problems quickly. Failure comment: This is a very simple fault, but if the thinking is not clear, inspection and judgment will not be able to find the root of the problem quickly. Therefore, we need to have a correct diagnosis and reasonable use of equipment, so that we can get twice the result with half the effort.