When I recently checked the oil level gas had accumulated in the crankcase and mixed with the oil. I replaced the fuel pump thinking that the diaphram was leaking fuel into the crankcase. After running the engine on the lake for approx 5 hours (two trips on the lake) fuel is still getting into the crankcase. How can fuel enter the crankcase other than through the fuel pump? What can I check before taking it to the dealer?