Abstract: A float valve is provided on an upper wall of a fuel tank and arranged to close a first port formed in the upper wall with a float actuated by the fuel level in the fuel tank. A vent tube is provided for communicating the first port with the atmosphere through a carbon canister. A solenoid operated valve is provided adjacent the float valve. The solenoid-operated valve has a vertically movable plunger, a spring for biasing the plunger to a second port to close it and a solenoid for attracting the plunger upon energization thereof so as to open the second port. The plunger is arranged to engage with the float valve so as to open the first port when the solenoid is energized. A switch is provided in a filler pipe so as to be operated by a filler nozzle inserted in the filler pipe for energizing the solenoid.