<p>A plastic fuel tank comprises a large main tank (1) and a small collecting tank connected to the main tank (1) by a flow-through opening (7). The collecting tank (3) is completely pulled into the underside (11) of the main tank (1), and includes vaulted lateral walls (31) which are symmetrical in all directions and expand into a bottom part (32) with an enlarged surface. The collecting tank (3) is partly surrounded by a connecting channel (8) opening from the main tank (1). The connecting channel (8) communicates with the collecting tank (3) via an admission bore (10). A nozzle (12) from the fuel return line (6) opens into the connecting channel (8) at a point opposite admission bore (10) to help propel fuel from the connecting channel (8) into the collecting tank (3).</p>