You might want to check and or replace the "O Ring" under fuel fill cap. That little sucker will crack over time from the gasoline (epecially E-10) & harsh additives. This results in water getting into your fuel every time it rains and every time you wash down the boat.
I would purchase a new one, add a little zipper grease to it and replace
Let me know if this solves your water intrusion issues
Chuck