Re: 9.9 4-stroke idle problems?
Dirty carb my friend. The tiny little jets on the four strokes are very prone to ANY contaminates in the fuel, no matter what size or composition. Pull the carb, disassemble, soak all pieces, blow dry with compressed air. Change in line filter, purge through lines on motor. Install clean carb. Verify fuel supply is CLEAN and WATER free. You should be good to go if all the above is completed and done correctly. ...until next time.