Had the same thing happen to me. Turned out to be the fill hoses. Looked fine from above. Once removed, the under side (touching the floor) had rotted to the point the the hose reinforcement wires where starting to rust and poked thru the outer jacket of the hose.But boat still leaks out gas when I fill them up. But it stop leaking after about between 30 minutes after I run the the boat and after that no leak I am just worried someone said might be over filling the tanks