Abstract: Fuel tank for a motor vehicle having a tank housing (1) that encapsulates a fuel space (2) divided by means of a number of lateral stiffening partitioning wall (4, 5) into fuel chambers (8, 9). These communicate with each other via openings (10-15) in the partitioning walls. The tank exhibits an outlet member (116) with a chosen position in one of the fuel chambers where the opening is delimited all around by means of an opening edge (26) which is arranged within the partitioning wall with a distance to the bottom of the tank. In one or more of the openings between the fuel chambers, a back valve (22) is arranged. By means of the clack valve, flow is permitted to the fuel chamber (7) with the outlet member (16), but in the opposite direction the flow is completely or partially prevented by means of which, in case of a sloping of the tank in its longitudinal direction, fuel is retained in the fuel chamber in which the outlet member is positioned.