Bill D 1,620 #1 Posted February 12 I have a Tecumseh OHSK120 on my neighbors snowblower that I cannot get to run correctly. I've changed the carb ( new OEM, Made in USA!) with some improvement, but it still surges and backfires. All indications are that it's running lean. I'm going to change the intake manifold gasket next. Thoughts? I'm running out of ideas on this and it's driving me crazy. Share this post Link to post Share on other sites
pfrederi 17,164 #2 Posted February 12 Lean due to inadequate fuel flow?? Filter ?? is there a pump? 1 Share this post Link to post Share on other sites
ri702bill 7,360 #3 Posted February 12 (edited) Lean at idle or WOT??? there are 2 different circuits. Lean at WOT is pretty simple - providing there are no vacuum leaks. Main jet adjusting screw is in the nut that holds the bowl on. You MAY need to back it out a half a turn or so... IF is a fixed jet..... good luck. Edited February 12 by ri702bill Share this post Link to post Share on other sites
WHX?? 46,838 #4 Posted February 13 Check the governor & linkage and adjust. Share this post Link to post Share on other sites
Howie 882 #5 Posted February 13 I'm going to guess that is a fixed jet carb on that snowblower. Gravity fed from the tank. I suppose the governor spring in the wrong hole could make overly sensitive. I have several spare bowl nuts and have checked for one with a couple thousands bigger hole to try. Sometimes it can help and sometimes not. Idle side and high speed circuits have to both be clean. Share this post Link to post Share on other sites
ri702bill 7,360 #6 Posted February 13 6 hours ago, Howie said: I'm going to guess that is a fixed jet carb on that snowblower. Gravity fed from the tank. I suppose the governor spring in the wrong hole could make overly sensitive. I have several spare bowl nuts and have checked for one with a couple thousands bigger hole to try. Sometimes it can help and sometimes not. Idle side and high speed circuits have to both be clean. Last sentence says it all ....... Share this post Link to post Share on other sites
JoeM 7,674 #7 Posted February 13 Spray a little carb cleaner around the joints and see if it smooths out but first I would apply a little choke to confirm the lean issue. What is the spark plug telling you? There can be so many things from mag gap to leaking valves etc. That looks like a newer machine and might have a screen in the tank impeding flow. Does it have a built in fuel bulb? take a close look there too. 1 Share this post Link to post Share on other sites
Bill D 1,620 #8 Posted February 13 I put a new carb on it. Old one was adjustable, new one is not. Starts better with the new carb but still runs lousy. I'm thinking the intake gasket could be leaking though I can't see any evidence. The engine sat for awhile before I got it. Gasket is probably dried out. Restarts fine when hot with one shot of primer. That make me think it isn't valves. Share this post Link to post Share on other sites
wallfish 15,940 #9 Posted February 13 11 minutes ago, Bill D said: That make me think it isn't valves. But the backfiring does. Carbon build up? Clogged muffler? Plus the things mentioned above. Share this post Link to post Share on other sites
