A fuel filler system for use in a vehicle is provided. The system includes a fuel filler tube, a locking bracket coupled to an inner surface of the fuel filler tube, and a closure device coupleable within the tube end and including an outer wall and a radially movable tab extending from the outer wall. The tab engages the locking bracket after rotation of the closure device from a first rotational position to a second rotational position to prevent rotation of the closure device relative to the locking bracket. The closure device further includes a web flexibly connecting the tab to the outer wall and a region of weakness defined in the web, such that upon forcible rotation of the closure device from the second rotational position to the first rotational position, the region of weakness facilitates separation of the web from the outer wall.