Abstract: In a fuel filling assembly to fill diesel fuel into a vehicle tank, having a slotted actuation bush (40), the actuation bush is fitted at its end facing the fuel tank with a drive segment on at least one side of said gap, and the actuation bush is configured in floating manner in a jar-like housing (30). A closure mechanism (50) is mounted at the actuation bush (40) end facing the fuel tank and is designed to constitute, in its closed position, a stop for an inserted fuel pump nozzle. The drive segment of the actuation bush engages the closure mechanism, whereby this closure mechanism is displaced out of the closed into the open position when the diesel fuel pump nozzle expands the actuation bush, the closure mechanism in its closed position closing in approximately sealing manner the passage to said tank.