Cub Cadet with KT725 only runs well under load

[Tillyton]

We have a Cub Cadet zero turn with a Kohler 7000 series KT725 engine. The mower has about 80 hours on it. For the first 50 or so hours it ran without problems, then one day starting to hunt revs and misfire. Went in under warranty for weeks but they couldn't find anything wrong (or so they said). I find I have to clean and rebuild the carby every few hours, and even then it is very temperamental. Basically, it will fire up first go, run for for a few minutes until I drive it to the lawn to be mown, around 60 seconds, but by the time I get there it is on the verge of dying. However, once I engage the mowing blades it will mow for hours without missing a beat. Within a few minutes of disengaging the blades, it starts running roughly again. Spark plugs are fine, have replaced fuel and fuel filter and choke is working as designed. Any ideas would be most welcome.

 

[7394]

Welcome Aboard, I'll let the experts chime in hopefully soon for ya.

 

[Tiger Small Engine]

Welcome Aboard, I'll let the experts chime in hopefully soon for ya.

Sounds like fuel delivery issue. This mower should still be under warranty. Find another shop for Cub Cadet and explain that another shop unsuccessfully repaired the issue. No reason at all you should be removin

Welcome Aboard, I'll let the experts chime in hopefully soon for ya.

Still under warranty, so find another shop to help you and explain your situation. Or give the original shop another chance.

Sounds like a fuel delivery issue or possible air leak. Spray carburetor cleaner carefully around intake and listen for changes in RPM.