Well, the problem is that the tank gets overfilled. I have a theory that the accordion is supposed to make the pump click off before the big 3" fill tube gets full, leaving half a gallon or so of void space. The fuel level would then be below the bend in the Vent hose, and hence make it more difficult for fuel to go up and out of the vent. I 've seen my vent leak fuel driving down the road, and also in the water once. This is extremely troubling to me and I am looking for a way to mitigate this. The best fix would be to move the fill neck down somehow, but the geometry of the hull doesn't really allow it, unless I have it on the side of the boat. Aside from being ugly, I feel like this would invite the possibility of letting water into the tank as this boat rides pretty low when not on plane. If I fill it slowly, it will only spew a little form the vent and that's when I cut it off, but I believe I still leak a little when the boat jostles in the water before I burn some off. Also, it takes forever having to hold the pump at slow speed. I've gotten pretty good at guessing when to slow down, but the engineer in me knows this is not a real solution.