Water in fuel?
 

My buddys boat keeps getting a lot of water in the fuel. The first time i drained the tank i pulled approx 5 gals of water out of 75 total gallons. The boat sat for about two months. We changed both the filters at the tank and the O/B's then filled with new fuel. We ran it, everything was good, put stabilizer in it two weeks later try to go out and same problem. This time i checked around the fuel sender and noticed gasket was bad around sending unit and repaired that. New gas again, stabilizer and everything went fine until the next journey. Dead in the water. Drained tank dry again and found same issue except we were lucky i never left the yard and it died in my yard instead of on the water. Anyone have a clue. Is it this ethanol or what else should be on my checklist to go thru and check. Its a 27 activator and the tank is built inbetween the stringers.

5 gallons is a lot more water than should ever be caused by condensation. My guess is that water is leaking into the tank or the fill nozzle somehow.

Yup. Sounds like rain water probably getting in somehow, somewhere like griff said. check Fuel fill o-ring is intact, etc. Or maybe even try a new source for fuel

Any chance a jacka$$ neighbor may be sabotaging?

Is the tank aluminum?
 

They fail often when there is standing water under or around that is in contact with the tank.

I have a friend that had the same problem, his fuel cap/tank vent was one piece. Every so often rain water would be channeled off the cover and towards the poorly designed vent and then into the tank. Drove is nuts, I installed and new cap with seperate vent and the problem was solved.

I one time in big seas got water in to the vent, several gallons. The vent needs to be directed away from water spray and also needs the hose looped upward above the thru hull inside the boat to prevent water infiltration. If the hose is looped high, any water that goes in just flows back out. Kind of an inverted trap.

Do you buy your fuel at at Marina? I found out the hard way that you can't always trust where you get your fuel. They can have leaky tanks too.

+1 on the vent. I have a friend that was fighting water issues all of last season. He even totally drained the tank and still had problems. One day when he was running his hand was over the side and got a quality splash which caused him to check the vents (totally facing the wrong direction and suckinng in water).

Good luck, Water in fuel sucks!!!!

Anybody have a good wesite for vents and fuel caps