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SmilinSam

Need a little advice on a Tecumseh Carb

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SmilinSam
Trying to get a Massey Lawn tractor running so I can get on with my Homelite restoration. I cleaned and put a new float valve in it put it on. It runs when you put gas in the carb( symptoms of a stuck float valve) It also tries to run when you full choke it and run it up to full throttle then back to idle. It fires and tries to run when you get to the idle position. It will do this consistently, but will not run for any length of time. Thought I'd ask for some input before I take it off again. What do ya'll think? Thanks for your time, Sam

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Mack
Maybe the screws holding the butterfly are loose.I had this problem once,only one screw holding the butterfly and acted as you described.When I took the head off the motor the other screw was embedded in it but you could tell it ratteled around in there before getting embedded.

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dlcentral
Main jet assy uder float bowl is probably plugged.Also those carbs plug internally for the idle circuit.So even if you clean out both small holes in the main jet it still may not idle.But beings you said it does idle,just the main jet and float bowl is probably your problem.

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SmilinSam
Float bowl is full of gas, but its not getting gas(or much of it) into the throttle body. I suppose its feasable that I got some dirt in the end of the fuel line when I put it through the engine behind the flywheel(like Tecumseh does). Could have plugged the main jet tube and not the float valve. Like I said it will run,briefly and only at idle after giving it full throttle while cranking then backing off.( or when you introduce gas into it by hand it will run faster) I would think if it were valves it would not start at all nor run Am I right?. So, it looks like another clean out tonight. Thannks, Sam

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SmilinSam
What size engine is it ? How clean is the carb ? Did you soak it or spray it out with gumout ? What do you have for adjustment screws on it ? There is usually a high speed or main adjustment on the bottom of the bowl and a idle on the side of the carburator. If these are not set correct it will not run or run properly. Did you replace the seat when you replaced the needle ? Did you adjust the float ? Let me know which you have done and then I can give you some more feedback. What is the Tecumseh eng.mod. number ?

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SmilinSam
I must also disagree with the anti Tecumseh thoughts. I have a few different machines with Tecumseh float carbs. on them. If they are adjusted properly they work quite well. The largest machine is a tiller with a 7 hp Tecumseh and it is almost 30 yrs. old, came from a farm and I would put it up against any Briggs of the same hp any time. If they are adjusted properly, they can give you plenty of years of satisfaction. Get back to me on my other reply and I will see if I can get you through this.

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JeffG
Throw it away! Tecumseh carb.'s are junk and you'll never get it working right. Sorry to be such a pessimist, but I've been down that road - and the carb.'s just can't really be made to perform properly. The later model Tecumseh's (in the last few years) finally have a good carb. on them and seem to perform well. Just my opinion, but I bet others will agree. Jeff

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SmilinSam
I have done all the standard cleaning adjusting(as per the book) and replacement of float valve and seat. I seem to have a restriction of fuel getting from the lower part of the carb to the upper throttle body. The only thing that has not been done is to remove the two welch plugs, clean out those areas and replace with new plugs. I'm not anti Tecumseh, but even a Tecumseh official has been quoted as saying that older tecumseh carbs are a problem peice. I have owned Wheel horse products with these engines and I have had good running ones and bad ones. The bad ones usually have been sitting and the carbs are all gummed up. I thus far only have a 50% success rate of getting those back to operating condition without replacing the carb. This is a 8HP on a MF8 lawn tractor from the late 60's or early 70's. I'm still open to suggestions. Sam

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JordB110
I would say if you have done all the correct stuff, cleaned carb., new needle and seat, proper adjustments on screws, adj.float, then maybe you should pop the welch plugs out to clean those areas. Read up on it first and just take your time doing so. It is easy to make a mistake doing it. It is not hard to do just put your carb gently in a vice and do as the book says. One other thing, do you have the bowl on the correct way with the shallow flat part over the needle and seat side ?

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SmilinSam
Yup, I got the bowl on right too. I took out a junk carb and experimented taking the plugs out on it. I can see how those little holes can plug up. When I get time I'll have to do that operation on the good carb(if you can call it good). But If that dosn't work, being pretty good at Frankenstein operations, I might try to graft a Kohler or newer Briggs carb onto the thing and see what happens. HA! who knows until someone tries. Sam

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MPH
Sam, the grafting could work. when I was a farmboy my bro and me put a briggs carb on a cliton engine for a mower we built. had a block of wood for an addaptor between the block and the carb, Dad sold it at the farm sale Years later. MPH

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SmilinSam
I believe the problem is behind the welch plugs. Briggs carbs are more forgiving during a cleanout and rebuild than Tecumseh. Apparrently you have to go the full nine yards on the Tecumseh. So when I get time I'll look into it again.

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kuhner
One other thought. When you put the carb back together did you use new parts ( adj.screws, o-rings, etc. ) If not check the tips of your adjustment screws to make sure they were never turned in too much that they could be damaged on the very end. I have had great succcess rebuilding Tecumseh float carbs when I pull the Welch plugs,remove all adj. screws,remove needle and little seat in hole then either soak in carb. cleaner or spray the dylights out of it with gumout. Are all the intake manifold bolts tight. Good luck

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kuhner
When the needle and seat were out did you spray with gumout and then compressed air through the hole where the seat goes? How about the float, I once had a float that had a pin hole in it so it would fill up with gas. If you take it off and shake it you could tell if this was the problem. If it's not too much of a problem I would start from square one again, strip it, clean it well, spray gumout through all holes, clean where welch plugs go and then use your book and put it all back together.

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KenW
Don't give up on that Tecumseh. Once you get it squared away you will be quite happy with it. I allways thought the big Briggs carbs were quite a pain. they either worked good or the were a problem. Good luck.

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