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Hot!Carburetor on Tecumseh Engine - Choke and Throttle Issue

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sgaster
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2024/05/25 14:25:23 (permalink)
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Carburetor on Tecumseh Engine - Choke and Throttle Issue

I'm mechanically adept, but carbs require experience I don't have. And I might be missing something here, so I figured it was worth asking. Forgive me if I don't use the correct part names.
Carburetor on Tecumseh engine on old Troy-bilt tiller seems to have a weak or missing spring that would control the closing of the throttle when the throttle cable is released. My perplexion is this occurs with the original carburetor and a new one just purchased. The only external spring I see is the one from the throttle linkage to the shaft. The throttle plate stays in any position it is manually put in. It does not spring close as I would expect. I can not find a diagram or evidence there is a missing spring but that is the only thing I can think of. And if there is an internal spring that is weak on the old carburetor, that would not explain the same behavior on the new carburetor. I had the thought there might be some sort of mechanism where air flow would be responsible for pulling the plate closed but that seems to be too weak. And if that is indeed true, then I still have the original issue of the engine not running when the choke is moved to the run position, with both the original and new carburetor.
To clarify, the resulting symptom, with both old and new carburetor, is it will crank fine with coke engaged, but trying to put choke in run position engines dies. And when the throttle cable is pulled, the throttle plate moves correctly and engine speed increases, but when the throttle is released the plate does not return to position. It over-revs and dies due to gas flooding. I always quickly turn it off to avoid engine damage.
Advice or links to anything useful would be appreciated.
Troy Bilt Tiller/Edger Model 128T
21A-128T063

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    SRTsFZ6
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    Re: Carburetor on Tecumseh Engine - Choke and Throttle Issue 2024/05/25 15:58:18 (permalink)
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    Can you post a model # of the engine?
     
    Looking at the parts diagram on Jacks, there isn't a throttle cable shown:
    https://www.jackssmallengines.com/jacks-parts-lookup/manufacturer/troy-bilt/21-tillers/2002-models/21a-128t063-tiller-edger-2002-128t-2002/general-assembly 
     
    I gather the governor is still attached to the engine and in working order or is there just a cable direct to the throttle butterfly?  (Someone would have modified it).
     
    Please advise..

    Scott
    sgaster
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    Re: Carburetor on Tecumseh Engine - Choke and Throttle Issue 2024/05/27 11:15:31 (permalink)
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    Thanks for answering. After messing with it, I realized the issue persisted even when I manually controlled the throttle valve. So the issue was regardless of the the throttle position. I took everything back apart and realized a gasket was covering the little hole on the carb. It was slightly misaligned. I assume that hole is part of what draws fuel/air into the chamber. I fixed that and then when trying to start it, the cord broke. :(
    I'll have to fix that and try again.
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