PURPOSE: To make any bubble discharge into a fuel tank easier by a method wherein a cylindrical filter is provided on an inlet of a fuel supply channel connected to the bottom of a fuel tank and a cylindrical tube is communicated with the upper end of the filter which is projected and opened higher than the fuel level in the fuel tank.

CONSTITUTION: A fuel supply tube 4 on engine side is connected to the bottom of a fuel tank 2 through a fuel cock 3. Then a netty cylindrical filter 6 is provided on the inlet side of the fuel cock 3 and the upper end of the filter is connected to the cylindrical tube 7. The upper end of the cylindrical tube 7 is extended higher than the fuel level 8 in the fuel tank 2 to be provided with an opening 7a for communication with the space within the fuel tank 2. Through these procedures, the bubble produced corresponding to the rise of fuel temperature and risen from the fuel supply tube 4 to the fuel tank 2 side reaches the cylindrical tube 7 passing inside the filter 6 to be discharged from the opening 7a to the space within the fuel tank 2. Resultantly the bubbles are arrested by the net surface of the cylindrical filter 6 without intercepting the fuel from running in A.