Engine speed mystery

Discussion in 'Mechanic and Repair' started by cutntrim, Aug 8, 2003.

  1. cutntrim

    cutntrim LawnSite Senior Member
    Messages: 474

    My Ransome Bobcat ZT 219 is frustrating me with a peculiar problem. On startup sometimes the engine will only run on half throttle, almost sounding as though the choke is stuck and then after 30sec. to 2 min it will magically hiccup and go full throttle.

    My service mechanic checked the throttle cable linkage and checked the choke but found nothing wrong. The fuel filter is fine, and I replaced the spark plugs but the problem remains.

    Once up to speed, the engine will remain that way until I go to start it at the next property. Then I've got a 50% chance of it not revving all the way up again.

    Any ideas?
  2. With all thats been checked my 1st thought is that the governor is sticking.
  3. cutntrim

    cutntrim LawnSite Senior Member
    Messages: 474

    Pretty sure he checked that too.
  4. 1grnlwn

    1grnlwn LawnSite Bronze Member
    Messages: 1,261

    Is the engine a Kaw?
  5. cutntrim

    cutntrim LawnSite Senior Member
    Messages: 474

    Yes, it's a Kawi 19.0hp.

    Messages: 153

    Check the jets in the carburetor. I have a Kawi FC150 5.5hp on my 21" Toro. After checking the spark plug, governor linkage, fuel
    filter, etc. I still had the same problem. Talked to the mechanic at
    the Toro dealer and he suggested that I check the governor gear.
    Ordered the parts and opened up the engine. NOT THE GEAR!
    All that was left was the carburetor. I dismantled the carb. and
    discovered the jets were dirty, After cleaning and re-installing, the
    engine runs great. I have ordered new jets, and will replace them.
    This engine is 4yrs. old and gets many hours of use per week.
    Hope this helps with your problem.
  7. cutntrim

    cutntrim LawnSite Senior Member
    Messages: 474

    Problem appears to be fixed. Kawasaki rep said it sounded like engine was only running on one cylinder (it's a twin). So, he suggested to pull the plug wire on each side (one at a time) and see if the engine rpm's dropped (as though on one cylinder) or quit entirely. They should drop but keep running since the other cylinder is still plugged in.

    Engine quit with the right wire pulled, so we ordered an ignition coil for the left side and since it's been installed no more problems.

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