PURPOSE: To prevent the variation of the air fuel ratio by arranging a fuel pump between a pump and a vaporizer in a fuel system for a liquidified gas engine thereby enabling the fuel supply to the vaporizer continuously under the liquid state.

CONSTITUTION: The liquidified gas is filled in a cylinder 1. The fuel in the cylinder 1 is fed through a filter 2 and a solenoid valve 3 for control to a vaporizer 4 continuously under pressurized state. The vaporized fuel is mixed with the sucked air in a mixer 5.