CV740-3029 Hunting & Surging

[Mr Mower Man]

I've got a 60" ZTR with a 27HP Kohler CV740-3029 that tends to hunt and surge a little at TNL speed, but not real bad. Runs fine at low idle. Put a load on the engine, and the RPM's are steady. Just yesterday, I noticed that if I pulled the choke out just a little bit, it would run smooth. And when I shoved the choke back in, it stayed running smooth...as long as the mower sat still and I didn't change the throttle. If I loaded the engine in any way by moving the mower, or lowered and then raised the throttle again, it would start to hunt & surge a little. Back before I sold this unit a year and a half ago, it would tend to do this sometimes. But it was running smooth at the time that I sold it. The customer was complaining that it's been doing it a long time, just about right after he bought it. I've heard that some of these Command engines are tuned extremely lean to pass emissions tests, and that hunting and surging is characteristic of them. I just called Kohler tech support, and the guy on the other end suggested I try a new governor spring, since they can be really touchy sometimes, before I go into something more drastic.

So, do you think I have a fuel system issue? Or is the governor system to blame? The performance problem is slight, and it has some characteristics of fuel restriction and other characteristics of a governor issue. Really not sure what tree to bark up. I do need to do a static governor adjustment on it. But aside from that, what are your thoughts?

[bgsengine]

Either/Or - Get it to where it is surging and then stop the throttle by hand manually from moving - if the engine tries to "adjust" (starts to stall a bit) then suspect fuel , if the surge goes away, suspect governor (static adjust and/or spring) is where I'd start on it.

[Mr Mower Man]

I think governor is where I'll be looking to start with. I can steady the governor by hand and it runs fine. And then when I let it go, sometimes it continues to run smooth for a few seconds before it starts to "bounce" again. Adjustment for sure and maybe a new governor spring. I'll let you know how it pans out. Thanks.

And Merry Christmas!