I lost my gas cap and bought one from the nearby store that "fit". I got stranded on the water and it seemed like the boat ran out of gas at apporximately 3/4 tank remaining. It occurred to me maybe the new cap was causing the problem. When I removed the cap a powerful air burst came out of the tank (i.e. it was under pressure). The boat started immediately after the cap was removed. Apparently, I bought a non-vented gas cap. Thus, does anyone know what type/brand/model of gas cap I should buy and where I can buy one? My boat is a 2005 outback carburated indmar assault engine.