Abstract: A flap valve for the filling pipe of a motor vehicle fuel tank, comprising a pipe section (3) that projects at a slant into the tank, a valve flap (2) that is positioned so as to rotate therein and has two pivoting arms (33), which project on the side from the pipe section, as well as a floater (1) that is guided axially on the outside peripheral surface of the pipe section. The pivoting arms (33) are hinged with their free ends to this floater. In the fully assembled state, the lower front of the floater (1) has an essentially horizontally extending plane, namely a frontal plane (17).