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Miller Bobcat 225g idle problems

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  • Miller Bobcat 225g idle problems

    I bought this used and it had a bunch of gunk in the gas tank. I have cleaned that out and installed new fuel filter. The previous owner had already had a mechanic clean the carburetor and it was running and welding when I bought it. I have put new spark plugs and new air filter.
    It has not been cranked in a couple of weeks.Today when I started it up it would not idle. You can see in the pictures and the video, the fuel filter is not completely fuel, the idle screw is turned in as far as it can go. I did move the idle solenoid forward to get it to idle, but the shutdown lever is not touching the idle screw and it seems to be idling really rough. I have posted the links to pictures of the fuel filter, vacum fuel pump and idle screw as well as a video.

    https://drive.google.com/file/d/1L5S...w?usp=drivesdk

    https://drive.google.com/file/d/1LBZ...w?usp=drivesdk

    https://drive.google.com/file/d/1LDq...w?usp=drivesdk

    https://drive.google.com/file/d/1LDZ...w?usp=drivesdk

    https://drive.google.com/file/d/1LS2...w?usp=drivesdk


    Any comments/suggestions are welcome.
    Thank you.
    Last edited by Chas007; 08-13-2021, 05:00 PM.

  • #2
    I can't get the google drive links to work, which is pretty typical - google drive is awful.

    About 99% of such problems are the carb, either needing cleaning or a new needle, seat, and a couple gaskets.

    Fuel filters are often partially full in low pressure systems like these - once fuel starts flowing through them, the air bubble gets stuck. Nothing to worry about.

    Does it run better if you put the choke on? Does it smooth out if you try welding or powering something substantial (a space heater at a minimum) on the ac output?

    Idling with the throttle butterflies abnormally far open usually means you have crud in the idle circuit, and it's time to clean the carb. If it welds/powers well even with the choke open, this is definitely the case. If it stalls out when you try welding or powering, even with the choke closed, that would point to a bad needle or seat, another carb problem, or a fuel supply issue.

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    • #3
      Originally posted by Bushytails View Post

      Idling with the throttle butterflies abnormally far open usually means you have crud in the idle circuit, and it's time to clean the carb. If it welds/powers well even with the choke open, this is definitely the case. If it stalls out when you try welding or powering, even with the choke closed, that would point to a bad needle or seat, another carb problem, or a fuel supply issue.
      It smokes a little with the choke on, but it still runs and does not die. With the choke off, if it were to throttle all the way back to the idle screw which is turned in all the way it dies. I have to choke it a little to start it back up.

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      • #4
        If it welds or powers without dying, with the choke on, it means it's time to clean the carb again, and inspect to see if rebuild parts are needed.

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        • #5
          What engine is on it?

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          • #6
            Can’t see the video or pictures.

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            • #7
              Originally posted by ryanjones2150 View Post
              What engine is on it?
              Onan P216G

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              • #8
                Originally posted by Kpack View Post
                Can’t see the video or pictures.
                I don't know why the links are not working. I have set each item to share with anyone who has the link.

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                • #9
                  Most Idle problems I have seen with the Bobcats is centered around the IDLE / JACKRABBIT Linkage and solenoid adjustments..........If the linkage is bound up at all its not working....I usually do a little WD-40 around all linkage points and it seems to like it.............And remember if your low on oil it will not run.....

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                  • #10
                    I believe from the symptoms it is running lean. Exhaust seems excessively hot, exhaust burns your eyes pretty bad, often have to choke it to start it even when the engine is warm, it doesn't want to low idle and it will weld and power equipment with choke on. I have ordered a new carburetor and fuel pump. I hope I can change the carburetor without having to remove the intake and exhaust. Once the new carburetor is on I guess I'll have to go back and readjust the low idle solenoid and idle screw.

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                    • #11
                      I just watched your video and that miss could be a burnt exhaust valve.....common with those motors...do a leak down test. A Rich mixture would burn your eyes.......Lean means all the fuel has been burned.
                      Last edited by tarry99; 08-14-2021, 09:35 PM.

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                      • #12
                        Originally posted by tarry99 View Post
                        I just watched your video and that miss could be a burnt exhaust valve.....common with those motors...do a leak down test. A Rich mixture would burn your eyes.......Lean means all the fuel has been burned.
                        Lean mixtures cause misfires, which cause unburnt fuel to enter the exhaust, also burning your eyes.

                        I need to do the valves on my 225NT... while cranking you can feel it suck your hand in against the exhaust... but it still starts eventually, and I have too many projects.

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                        • #13
                          If you put a piece of paper over the exhaust of a vehicle, if it has a bad valve, the paper will keep sucking to the tailpipe and letting go as the engine idles..

                          My Mustang straight six had a bad valve.
                          Last edited by tackit; 08-14-2021, 10:00 PM.

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                          • #14
                            Clean the carb again and dont use E10 gas.

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                            • #15
                              Is there a way to change this carburetor without removing the intake manifold and muffler?

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