These engines (all small 4-stroke engines) are incredibly susceptible to problems stemming from water in fuel. Before I tried the Startron, we would have issues after simply filling the engine on a wet/foggy morning. It did not take much to upset the engine. Usually, it became difficult to start or sometimes it would begin to stall and require choke even at full speed to stay running. All I had to do to get beyond "the moment" was to drain the carb bowl and start it again.On we would go until another tiny drop of water showed up in the bowl...

Once I began adding Startron to the fuel, We never had an issue again. I am always careful with my fuel but wow!

The only reason I sold my Yamaha 2.5 in the end was not related to the fuel issue at all. Rather, the Trinka dinghy we use used to allow the engine to assume an angle it didn't like when it was sitting unladen and upon restart it smoked like a fog machine! I even tried a second motor and it was the same... Drove me crazy...We never had that issue when we used the engine on our "backup" roll up inflatable. That had enough buoyancy to support the engine at an angle it liked.