Be sure not to leave the newer fuel that contains alcohol inside the engine
over the winter. Run the engine
with the fuel valve closed so as to get rid of the last of it inside the engine.
At work we had an older carbureted outboard
that kept fouling on the newer gasoline with alcohol. Even with fuel stabilizer meant specifically for gasoline/alcohol mixtures, it kept fouling the carb jets. The partial solution was to run all the fuel out of the engine after each use. After three expensive trips to the outboard
shop to have the carburetor jets cleaned out, we gave up and replaced it with a fuel injected outboard. Problem solved
The alcohol is a problem for many older carbureted engines and fuel stabilizer sometimes is not a solution. Its probably at least worth a try.