No announcement yet.

Bobcat 225 NT surging

  • Filter
  • Time
  • Show
Clear All
new posts

  • Bobcat 225 NT surging

    My 225 NT runs fine while idling, but surges constantly while in the run setting. The solenoid continually adjusts the throttle setting.
    Does anybody have any ideas as to what's causing the surging?

  • #2
    Are you sure the solenoid is continually adjusting it? If so, that would point to some problem with the automatic idle circuitry constantly trying to switch between run and idle.

    If the solenoid isn't actually continually adjusting it, and the throttle is instead being adjusted by the mechanical governor as usual, surging problems are virtually always a dirty carburetor, bad fuel, bad fuel pump, or bad spark plugs, in that order. Checking the fuel and replacing the spark plugs are easy and cheap, so you can try them first. Cleaning the carb and installing a rebuild kit isn't too hard if you're good with small parts and paying attention to what went where, or any small engine shop can do it, or your local miller service place. Valve adjustment usually causes problems at idle that go away at run, so it's probably not that.

    Last edited by Bushytails; 05-21-2020, 10:52 PM.


    • #3
      Solenoid has nothing to do with your problem. It is called an idle solenoid and that's all it does. It's completely disengaged when welding. So your problem is carburetor or linkage. There is a thin spring connected to the linkage and it rots away or breaks. With your machine being at least 20 years old I suspect either. If it turns out to be the carburetor you can purchase and aftermarket ( I presume your engine is an Onan) for less than $50. Don't bother trying to clean yours for that price.


      • #4
        Thanks much......I had previously installed a brand new carburetor, so that's not the problem. I'll look for the thin spring that you described, and post a picture here, to make sure I'm on the same wavelength with you.
        Again, thanks alot for your input!


        • #5
          Also, thanks to Bushytails for listing the additional possible causes, in rank order!


          • #6
            Glad to help! Just because a carb is new doesn't eliminate it as the source of problems... Old gas and letting a unit sit will gum up the carb in a couple months...


            • #7
              Yeah--ask my weedeater I tried to use for the first time this year on Friday....even with Stabil in ethanol-free gas!