For the fuel pump inside the fuel tank, the installation structure of the regulator valve cap is not adequate, and therefore, fuel can permeate the cap and cause it to swell, and as a result the cap could become loose. If this problem is left unattended and an impact is caused on the fuel tank when driving over the curb etc., the cap may come off causing the regulator valve to fall off, in which case, the engine does not get fuel, so it stops and will not restart.