Observation on fuel

[guitarsnlikker]

There is a small marina on lake close by I use from time to time. Every time my boat has his gas (ethanol free) filled in the tank the engine will run on after turning off ignition. Sometimes a bit violently. Me no like that! I asked him what the octane is in his fuel and I did not get a satisfying answer. When I use mostly Sunoco 90 octane (ethanol free) from a local gas station in the tank it never runs on and shuts down perfectly. EVERYTIME. Mercruiser says it is built for 87 octane, I don't believe it.
Thoughts?

 

[achris]

It may not be the octane of the fuel, it could be something as simple as the lake marina pump is using 'winter' fuel and not making the change to 'summer' fuel at the right time.

Chris.......