I've been getting water in my fuel tank and I'm not sure where it's coming from. My boat is a Javelin 396 with a 30 gallon plastic fuel tank pushed by a 200 Johnson GT. I suspect the vent cap despite the little semi-circular shield over it. I've installed a fuel/water separator but wonder if there is any fuel additive that will neutralize the water already in the tank??? :-\
If it's real bad with water empty the tank but you could give STA-BIL a try and add a fuel/water separator to help prevent future water build up.