Need advice. Recently had trouble with carb. Tried getting fixed,couldnt get it to work right, so bought remanufactured carb. Has ran fine every since. Ran boat for couple of weeks no problem, until we put gas in from a different marina than usual. Never see anybody getting gas there. About 30 min. running boat full throttle it started backfiring. Back of throttle front of boat drops and then runs fine. Once you give more throttle after boat gets on plane starts backfiring again, Could this be water in the gas tank reaching carb from the boat being tilted back? Any advise would be greatly appreciated. New to the boating world. 5.0L 228 mercruiser
