I am having trouble with my O'Day 27 Saildrive 15 hp engine. I gave it a spring tune up and ran her six hours from the Calumet River to Montrose harbor in Chicago and it ran fine. The next week the engine would not turn over and it seemed there was water on the spark plugs. The batteries are charged and I am running out of options before I try to hire a mechanic. Also, my fuel filter seems to be working just fine. Does it sound like I have to drain my fuel tank and clean it out? Bob