OH NO!!! Not the Perko fill cap!! I've got one on my second boat, what a total PIA!!! You have to put gas in very slow because if too fast it blocks the air coming back out the vent, you can not put gas in with a can unless you use a funnel in the large hole so it will vent and number one it will leak water in the tank if the O-ring is not in place. Hate those fillers!!!!
http://perko.com/catalog/fuel_system...-_angled_neck/