[Arxkanbird]

Hi folks,
I have a Kawasaki Mule with the FE290D single-cylinder engine. When I first acquired it, I had to replace the carburetor because it had been sitting several years and wouldn't run at all. I used an OEM carb. Since then, it's had a buck/surge at light throttle and won't idle when hot for more than a minute or so. When it dies, it restarts instantly with choke or after 3-5 seconds without choke. Full throttle power is fine. The engine doesn't miss at idle, but rather, the speed wavers until it suddenly quits. In addition to the carb, I've replaced the spark plug, ignition coil (gapped to spec), fuel filter, hoses, and air filter. I adjusted the valves to spec. The engine has about 300 hours on it, probably less--someone left the key on which probably put a hundred hours on the clock. The idle air passages are clear in the carb. The idle air screw does affect the idle but doesn't prevent it from stalling. It won't idle at all unless the throttle is held slightly off the closed stop. I've cleaned the idle jet multiple times and tried a larger size to no effect.

I made a video of the behavior.

What should be my next troubleshooting step?

Thanks!

 

[Corday]

Linkage?

 

[Arxkanbird]

Linkage?

I've checked and cleaned the linkage, but that doesn't seem to be the issue. The loping/stalling at idle happens with fixed throttle position at the carburetor.

 

[Corday]

Old Gas?

 

[Arxkanbird]

Old Gas?

Nope, just a week or two old. The carb bowl had some cloudy stuff, but I drained it and found no varnish in the carb. I haven't tried blowing out or cleaning the passage feeding the idle jet. It behaved this way when the carb was brand new a few years ago.

 

[cotswoldstony]

First change the spark plug only fit NGK make of plug they are the best.
It sounds like a fuel problem if using pump fuel these carbs hate the ethanol in it which attracts water from the atmosphere. the jet running in the middle of the carb needs removing and all compontents ultrasonic cleaning.
Rebuilding carb float height is important for the engine to run correctly.
Float valve operation very important on machines with electric fuel pumps which can cause over fueling and uneven running.
Remove the complete fuel unit from the fuel tank under the seat and replace the fuel filter on the bottom of the unit and fit an inline fuel filter in the fuel line to the carb first before dismantling the carb.