kohler ch740s bogs when hot

Discussion in 'Mechanic and Repair' started by jbssc, May 11, 2008.

  1. jbssc

    jbssc LawnSite Member
    Messages: 3

    I have a Lazer Z with a Kohler CH740s. New plugs, air filter, oil filter, and blades. The engine cranks easily. Runs perfectly for 10 to 20 minutes. After cutting moderately thick grass the engine loses power. It sounds like its running at about 80% of full power. If you allow the engine to cool competely, the same symptoms can be repeated. On one occasion, I disengaged the blade, waited for about a minute, and could detect the engine return to full power. However, about a minute later it bogged again, and that was it for the day. The problem has been occurring for a while but appears to be getting worse. I have not checked the spark after this happens, so thats the next thing I plan to look into. Any ideas?
  2. Bill Kapaun

    Bill Kapaun LawnSite Senior Member
    Messages: 956

    A restricted fuel filter could cause that.
    When under load, the engine requires more fuel. IF the filter is allowing ALMOST enough through, the carb will slowly run out of gas.
  3. jbssc

    jbssc LawnSite Member
    Messages: 3

    I forget to mention, I also replaced the fuel filter. Although I did notice that the fuel filter is not full of fuel. It has air trapped inside. Is that normal?
  4. GravelyNut

    GravelyNut LawnSite Bronze Member
    Messages: 1,594

    Most filters never fill fully.

Share This Page