8n idle, rising and falling

I'm going to try to attach a video... tractor idles up fine for a couple seconds, then tries to die... then the governor catches it and pulls it up again, and cycle repeats... this tractor was not doing this when parked about 3 weeks ago, just started doing it today when we started it to move it into the barn for winter.
Surging idle... video...
 
I believe you are having governor problems. Crank it and hold the governor arm and see if it stays steady. If so, it's in the governor.
 
Check your fuel flow through the carb to make sure you have sufficient
flow. Could be as simple as a dirty screen causing it to run lean.
With the drain plug out of the bottom of the carb, turn the gas on
and catch it in a jar to inspect for water/debris. Should run a pint
in two minutes or so. On the bright side, the governor works.
 
thank you, all. I'll check fuel supply (I think that fuel sediment bowl should be replaced)... we did take the tank off and cleaned it out well back in the summer.

I appreciate the help.
 
The governor is only doing it's job, you have carburetor issues.

When the idle circuit/shystem in the carb isn't supplying enough fuel to feed the engine at idle speed the engine will slow down 'til the governor has yanked the throttle butterfly in the carb open enough and when enough time has transpired to get fuel flowing through the "load" circuit again RPM's rapidly increase.

Then the governor reacts to the rapid RPM increase and closes the throttle butterfly in the carb down into the "idle circuit" range, the idle circuit in the carb again doesn't supply enough fuel, and the cycle repeats.
 

Mine does the same but only during cold starts, only at idle and only in the winter. It doesn’t surge any other time of year or when the engine is warm or if I throttle it up above idle. I honestly dont worry about it.
 
Tony, if yours doesn't bother you to run it that way then I wouldn't
worry about it either. Only when cold, only at idle and at no other
time would suggest to me that your idle circuit is a bit lean during
the winter months but you're not going to run it there anyways.
Even if you did, it would warm up shortly and be fine.

If you are curious and want to experiment with it, try turning the
idle air screw in 1/16 to 1/8 turn when cold out. You would likely
need to reverse that change when the weather warms up though,
so as you said, maybe not worth even messing with.
 

Rouse thanks for the help. I’ll give it a shot next time I start it cold. It hasn’t started surging yet but when the temps drop some more I know it will.
 

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