Tecumseh snowblower engine: High RPM issues

Discussion in 'Mechanic and Repair' started by Glenn J, Nov 26, 2005.

  1. Glenn J

    Glenn J LawnSite Member
    Posts: 211

    The engine is on a Snapper 826 snowblower from the mid/late 80's. Luckily for me, it saw very little use from the previous (original) owner and has served me well for the past few years.

    Last year, I noticed some fluctuating/sumbling at high rpms. It liked to have the choke one just a bit in order to run right. Only after the engine was good and warm, could I take the choke off.

    Today, I pulled the bowl off the carb and gave it a good cleaning. After getting it all together, I could not get the machine to idle correctly. The idle kept going up and down...without me touched the throttle. That little arm on the block kept moving. I played with the screw under the bowl and the one on the side of the body of the carb. I'm now at a point where it idles good and the RPM stays constant when I move the throttle.

    The problem now is, it won't run smoothly past say 3/4 throttle. Once it gets passed that point, it stumbled really bad. And sounds like it wants to die out. I'm not sure if I'm running too rich or too lean. Any ideas where to start?
     
  2. hole in one lco

    hole in one lco LawnSite Bronze Member
    Posts: 1,795

    what color is the smoke
     
  3. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    The adjuster on the side is for the low speed circuit and sounds like you have that one adjusted just fine. The one on the bottom is for the high speed. When screwed in it leans the carb. out, When screwed out it rich-ens the carb. I would suggest pulling the spark plug and look at it, If it's black and sooty looking replace it and start the engine and rev wide open then adjust the bottom or high speed adjuster screwing inward slowly and see if it smooths out. If it gets worse screw it back out until it smooths out.
    These older carbs. had a non serviceable check ball inside, If it is clean and still wont run properly at any adjustments the carb. needs to be replaced.

    Good Luck
     
  4. Glenn J

    Glenn J LawnSite Member
    Posts: 211

    Thanks for the quick reply restrorob! Is that ball located in the bottom screw? I thought there was something in there when I took it out. I may have been lost in the shuffle. D'oh!
     
  5. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    No, It's inside a passage that can not be accessed for cleaning. It will get stuck in the passage and cause the engine to hunt and run erratically.
     
  6. Glenn J

    Glenn J LawnSite Member
    Posts: 211

    Gotcha! I'll try the adjuster on the bottom of the bowl.

    If that doesn't do it, does the entire carb need to be replaced?
     
  7. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Yes, I'm afraid so thats the easiest way to go.
     
  8. Glenn J

    Glenn J LawnSite Member
    Posts: 211

  9. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Probably somewhere in the 50 to 75 $ range if I had to guess, Not too bad to make a unit run and perform correctly. Continued use of any unit that is running incorrectly only causes more harm than good.
     
  10. Glenn J

    Glenn J LawnSite Member
    Posts: 211

    I'll be adjusting it this week again. If I can't get it dialed in, I'll pick up a new one.

    Too bad that spare carb I have from the old 12.5 Briggs won't work. :D
     

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