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Not wanting to idle


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My ol mule is acting up suddenly. It doesn't want to idle, it revs prefect just not idle. It eventually dies. I'm thinking something in The idle passage is plugged. Any other suggestions are appreciated that I may have over looked.

Brand new Wix fuel filter. That carb has been on for 19 years and never cleaned. Just b12 chemtool in the tank. I may hook up an auxiliary tank and see if it's fuel lines. But probably not since it revs fine.

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Couple things, if the new spark plug was a different heat range, it would affect the idle characteristics.  Second, the idle air screw having trash or corrosion will do this. 

For those that don't understand carburetor fundamentals, the carb runs off the idle air screw from idle to about 2500 rpms.  From about 2500 to 3500rpms, it's a combination of idle air and main jet fueling.  After 3500 rpms it's all main jet fueling.  So, hopefully that helps some folks narrow down their carburetor troubleshooting.  

For example, idles fine but boggs down at higher rpms, you have main jet issues (the big one that pokes up through the middle of the carb).  Bad idle but runs with open throttle, idle air issues (usually a screw or smaller needle type, may be under a thin tin cap that you drill or pry out (EPA thing), up in the front of the carb). 

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Okay, weird thing. 

Go out and fire up the mule, it idles PERFECT. I drove it around for about 10 minutes. Then let it idle for several minutes. Drive it around some more. Then let it idle, idles perfect.

I guess the b12 chemtool I put in it worked it's magic...

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  • 3 weeks later...

My 610 Mule will idle about 20 seconds the puff and dies, starts right back up.  I have cleaned carb , no help then replaced with new carb, new plug, new fuel pump, new gas lines , removed tank to make sure it was clean.  i have run seaform in it too.  Could it be a vacuum problem or do I need to drill out cap and adjust carb??


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Will it stay running if you rev it up to a constant high RPM?

I would also play with the choke a bit, and see if it idles or won't die on partial or almost full choke.

Did you replace the carburetor with a new OEM Kawasaki or a Chinesium off of ebay/Amazon?

It's possible (Even on a new Low quality carb) for the float (which regulates fuel flow into the carb bowl) to get stuck in the closed position, which prevents any more fuel from flowing into the bowl.


It's possible it's a vacuum problem.

It's also possible, but not as likely the ignition coil is failing, but they generally don't start right back up.

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3 minutes ago, Pamm r said:

ok great, that may be it, so if so, the cap looks new , do i just try to take it apart to see or look for a hole?


Generally you either replace it or I've let them soak in a solvent bath, ( gasoline)

Due to EPA regs the cap vent is fairly complicated.

Let me see if I can find a picture of The gas cap and see....

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The gas caps have little silicone flapper disks in them that vent one-way.  When they start to deteriorate they get really sticky and ambient pressures aren't enough to break the seal.  The pressure you're sensing when opening the cap may be air rushing into the gas tank.  

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