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139cc Yardman losing power

Discussion in 'Mechanic and Repair' started by babalu, Jan 26, 2008.

  1. babalu

    babalu LawnSite Member
    from 97411
    Posts: 2

    My 139cc OHC Honda powered Yardman mower is less than a year old with light once a week use and it is losing power. The more I run it, the worse it gets. I've cleaned the carb and air filter, cleaned and gapped the plug and it runs great for 5 minutes then slowly loses power until it won't cut anymore and becomes hard to restart. The plug looked like it was running lean with a white deposit on the tip. Any ideas?

    Thanks,
    Babalu
     
  2. Jay Ray

    Jay Ray LawnSite Fanatic
    Posts: 6,510

    First thing I think of is ignition module/coil when it gets worse as it heats up.
     
  3. babalu

    babalu LawnSite Member
    from 97411
    Posts: 2

    Jeez, this machine isn't that old and gets used only every other week, less in winter. I got it just a year ago. When you say ignition module, is it a coil ignition or electronic/magnetic sensor ignition? Will I need a specialized flywheel puller to get to the puppy?

    Thanks,
    Walter
     
  4. Jay Ray

    Jay Ray LawnSite Fanatic
    Posts: 6,510

    I'm not a qualified small engine mechanic, just have experience repairing my own stuff. IM/coil is the first thing I think of, but that is just one possibility. Hopefully someone with experience with the 139cc Honda, or one of the truly experienced small engine mechanics comes along on the board soon and can pinpoint it. If I were you, go ahead and post everthing on the engine ID plate: model no., spec., serial no., whatever identifies it, because they will ask for it.

    I guess if you give it a shot of ether when it is hot and then if it starts easy, that would indicate a fuel problem rather than ignition. I remove the air filter and spray. I wear a face shield just in case (only when it is hot, not cold), makes me feel stupid, but you never know.

    Unless Honda is different, the ignition is on the outside of the flywheel so you shouldn't have to pull it.

    If it has a fuel filter, that could be it. Also a pinhole crack in a fuel hose can absolutely drive you crazy suspecting everything else when a new nose solves the problem. Also loosen the gas cap and see if it runs okay. Just some ideas. Hope a real mechanic posts soon.
     

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