A fuel tank with a venting system includes a flap for closing and opening a vent made in the tank. The flap is coupled to a float. The flap includes a valve coupled to a second float mounted in a hinged manner in the tank so that the valve adopts a closed position, being pushed by the second float when the level of fuel in the tank reaches a certain threshold, and an open venting position in order to prevent overpressure within the tank, being driven by the second float when the level of fuel is below the threshold and the force exerted by the internal pressure on the valve is less than the sum of the forces exerted on the valve by the atmospheric pressure and by the weight of the second float.