Abstract: In at least one implementation, a filler neck for a fuel tank may include an outer tube attached to the fuel tank through which fuel is discharged into the fuel tank during a refueling event, and an insert. The insert may be carried by the outer tube and have a passage adapted to receive a refueling nozzle during a refueling event, a first barrier adapted to engage a refueling nozzle inserted in the passage and having one or more gaps through which fluid may flow between the refueling nozzle and first barrier, and a second barrier adapted to engage the first barrier to reduce the size of the gaps when the first barrier is engaged with a refueling nozzle.