A 2012 BMW X5 sport utility vehicle with a mileage of about 20 thousand km. User reflection: the car can't normally add fuel. Inspection and analysis: the maintenance personnel tried the car and found that when the car was refueling, the oil gun of the gas station always jumped for no reason. Through consulting relevant information, we know that the gun jumping mechanism of the fuel gun is triggered by the venturi negative pressure hole located at the head of the gun. Now that there is an abnormal jumping phenomenon, it is clear that fuel must be spatter to the outlet of the fuel gun. Check the refueling line and find that there is a stuck phenomenon in the one-way valve plate used to prevent fuel overflow when the vehicle is bumping. This will cause fuel to reflect from the valve plate and spatter to the outlet of the fuel gun, thus triggering the jump gun. Troubleshooting: replace the refueling pipeline, troubleshooting.