Originally Posted by shunra
As far as I know I still have the original cap. My cap is sligtly different than the one pictured above. I bet mine is the same as yours. Mine does not have a grip round the Circumference. It is almost impossible to turn by hand, you pretty much need to use the tool.
I am not near the boat to get a picture of the cap. Do you have a picture?
As far as I can tell my cap wasn't designed to be a vent.
I filled up again this weekend and tried to pay more attention to the sound. I belive it is suction. If you only loosen the cap sligtly the sound can last for several seconds.
I don't have a pic, but mine doesn't have the grip around the circumfereence either.. If I don't tighten the cap hard, of coarse I'll hear no sound next time I refuel. If I do tighten it hard, I hear a whoosh every time, and if i open it slow it can indeed last for several seconds.
It doesn't seem like a vent is designed into the system. It may be that those that hear nothing just don't tighten the cap as hard as I do. The first time I went to refuel I almost needed a lever arm as the simple cap wrench wasn't enough. I think it was made more difficult by the suction behind the cap..