tecumseh misfire

Discussion in 'Mechanic and Repair' started by dallaspaco, Apr 10, 2010.

  1. dallaspaco

    dallaspaco LawnSite Member
    Posts: 16

    I have a tecumseh 5.5 hp lawn mower engine 143.985500 It starts great and has enough power to mow the lawn with no problems.It has a misfire ,mainly not under load,but occasionally when working hard too.It has great compression,I put a new head gasket on it and cleaned it all good while I was in there.I use high grade gasoline and have added sea foam thinking it would help out.I was wandering if this motor is known for misfires and what I should do to correct it.I have also cleaned the carb.twice...thank you for any help
  2. topsites

    topsites LawnSite Fanatic
    Posts: 21,653

    What's the spark plug gap set to?
    Have you tried die-electric on the plug tip where the coil wire plugs onto?
  3. sharkey

    sharkey LawnSite Member
    from Pa
    Posts: 48

    How many hours are on the engine? If your not sure, how old is it?
  4. dallaspaco

    dallaspaco LawnSite Member
    Posts: 16

    I was under the impression that the spark plugs are gapped properly from the factory.I just put a new plug in it with no difference in results. I bought this mower used so I don't know the hours and only assume 8-10 years old

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