A cap is provided for use in the filler neck of a tank. The cap includes a closure mechanism for closing the filler neck and a handle mechanism for rotating the closure mechanism relative to the filler neck to a sealed position engaging the filler neck and establishing a sealed connection between the closure mechanism and the filler neck. The cap also includes a delayed actuation mechanism for providing a lost-motion driving connection between the handle mechanism and the closure mechanism and an indicator mechanism for providing an indication of sealed closure of the filler neck upon movement of the closure mechanism in the filler neck to its sealed position. The indicator mechanism includes an indicator affixed to the delayed actuation mechanism and the indicator is a reflective member visible to a user of the fuel cap.