12hp tacumseh

Widow lady dow the road working on her craftsman with 12hp tacumseh . It hadn't run in many years ,I put in new battery,cleaned fuel tank, new spark plug,and rebuilt carb . Engine runs smooth but wants to surge. I think the governor need to be adjusted but I don't know how. Can someone steer me in the right direction?thanks in advance for any help.

Before you jump into governor adjusting,look carefully to see if someone has bent or otherwise tampered with the governor linkage. It usually is pretty close to right when you reinstall the carburetor after just cleaning it. See if closing the choke slightly helps smooth it out. A lean mixture will cause surging and a rich mix will cause smoking usually along with some surge.Look to see if there is a knurled screw head with a spring on the shank of it in the bowl nut. Try readjusting this main fuel jet some. If there is no main jet needle for adjustment, then try closing the choke to richen up the mixture. The tiny main jet fuel passages in the nut that holds the bowl on are often overlooked when cleaning. Soaking it in the gallon can type of carburetor cleaner is usually the surest way to clean the little holes before blowing it out with air pressure. Be careful when blowing air into the inlet fitting. Only blow it from the needle valve side unless you have removed the rubber needle seat.

Good reply! Tacumseh engines and carbs can be a real pain. They can also be very reliable. I have three of them on a tiller gen set and snowblower etc. I set the main jet to run on HI-Test with a little Star-tron in the gas. Solved all kinds of hunting problems. Linkage problems can be a loose spring on the govenor linkage too. All of my generators including the 5200 with a 10hp tacumseh are set for hi-test. regular will not hold up worth a crap and you need to tweek the main jet almost every fill up. A good bet would be to purchase a new carb on fle bay. They are cheep enough. Don"t give up but a new carb may solve everything. You may want to find an older repair shop who knows how on these engines. May be your BEST bet. Jeffcat

I have had this issue on a number of small engines, old and new, with non-adjustable fuel jets. They just run too lean on gasahol. In each case I have opened the jet by 10% (by area not diameter) and they run perfect. Just my experience.

Jim

There are two possible causes of surgeing/eng hunting for it's speed on the tecumseh hh100/hh120 eng.

The most common cause is dirt/gum in the internal idle passages of carb body,you said you rebuilt carb,if all you did was clean out bowl,replaced float needle/needle seat & bowl gasket this is not a complete rebuilt,a complete rebuild requires soaking carb body in cleaner then removing ALL welch plugs/brass plugs in body & run a fine wire thru carb body passages & blow out with comressed air then replaceing all welch plugs/brass plugs as needed.

The 2nd possible cause is IF you removed brass main jet nozzle from carb body & nozzle is old style that has full length threads the chances are very high the tiny hole in threads & hole in main jet casting for idle circuit fuel supply are not lined up & idle circuit getting little/no gas.Click on link below & read text/look at drawing about nozzle,if you have to replace nozzle same are getting to be hard to come by & expensive,depend on orig pn of carb there are 3-4 different pn nozzles & they run $13-$15.

As jeffcat said you're probably ahead of the game going to ebay & buying a new oem/aftermarket carb(expensive)yrs ago I gave up on rebuilding orig tecumseh/walbro carbs with mixed results for the hh100/120 eng,I now use aftermarket oregon carbs(bought on ebay) designed for the tecumseh hm100 eng,with 2 small modifications they work great on the hh series eng,I've been useing these on an hh100 & hh120 for over 5 yrs without any problems.
nozzle

I think thats how all old Tecumsehs run. They even out under load.

Thank you all for your replies.Guess I'll check out ebay.