Kohler 725 surging - out of ideas
 

I'm new to this forum, so hoping to pick the brains of the experts.

I have a Cub Cadet XT1 LT46 I bought in 2016 with a Kohler 725 engine in it. Last Fall it started surging when I started it. I added Fuel Mechanic to it and it seemed to smooth it out. When I put away for winter, I changed oil, drained tank, etc. to store it as I normally do.

This year, the surging continued. So I bit the bullet and changed the fuel lines, fuel filter, air cleaner, brand new carburetor, fuel pump, and drained the tank again and put fresh fuel in it.

It's still surging. With the air cleaner off and motor running I have observed the governor assembly arm rocking back n' forth so it's obviously still starving for fuel but can't seem to find it. I am hoping it's not the governor pinion since the engine is not that old and only about 60 hours on it. Still seems to be fuel related. I typically buy regular fuel (89) from a brand station (Shell or Sunoco) and have not had an issue before now. I checked the breather lines as well and find not break or crack that might be letting excessive air in...

I still suspect a fuel related issue since it does seem to smooth out a bit the longer it runs, but when I engage the blades, the surging is more noticeable.

I hope I've provided enough detail here. Am I missing something? Any ideas would be appreciated. I'm invested into this now and would prefer to solve it rather than haul it to a small engine shop. :Thanks:

Is it still under warranty?

Not under warranty any more.

I had a old Allis Chalmers that use to do that. An adjustment on the governor fixed it. That may not apply in your case though.

I had a surging Briggs engine that ended up being a leak between the block and the plastic intake tube.

What was the old trick of spraying something around areas checking for intake leaks. WD40 brake cleaner? Anyone remember?