120 Johnson fuel issue

Hey guys, been lurking for a while and decided I may as well join the fray. A few days ago I purchased an old '85 Skeeter Starfire 115 with an '85 120 Johnson on it. The boat had sat for about a year, but the fuel still smells fine and the carbs aren't gummed up at all (at least the two that I opened up. The problem I'm having is a popping in the exhaust and a misfire at low rpm's. With the airbox off, the are occasional little "spits" of fuel coming from the larger of the two jets on the front of several of the carbs and the airbox had probably a couple of tablespoons of fuel in it when I pulled it off. It starts fine, and runs great at high speed (showed 53 mph on GPS), but as soon as I throttle it back, it goes to missing again. The top right plug is wetter than the rest, but they're all wet after idling. It has new plugs in it and compression is 135-140 on all cylinders. I'm thinking maybe a bad reed valve, but I'm not a two-stroke guy. Any suggestions?

Re: 120 Johnson fuel issue

What you describe sounds like what the guys here would call a lean "sneeze" or a cough that spits back fuel out the carb throats. You will want to solve this as it isnt good to run any cylinder lean, and can eventually harm you reeds.

This is usually Carb related. You should look at doing a carb kit rebuild, with particular attention to the low Idle jets. You could take a mixed gas/oil spray bottle and spray into the carbs one at a time, and see if it will isolate which one has the lean sneeze. Else, since it sat so long, it might be good maintenance to just go ahead and do the carb work.

Just had this scenerio....J115 not idling good at all with it sneezing back. I did alot of things to help it. But I remembered I had a set of rebult carbs off another motor (albiet 1 3/16 vs 1 5/16 originally), but decided it wasnt alot of work to put them on and test them to see. IMMEDIATLY was a huge difference. SNEEZE gone, it idled great finally. They are still on there and motor running great.

Look at cleaning out those carbs, passing a small fine wire through all openings and get a good carb cleaner with the rebuild kits.