Kohler CH18 Command engine not firing on all cylinders

[garydee]

Cut about half an acre of grass the other day with my 1864. Upon finishing, I reduced the idle to let the engine cool down then grabbed a tarp to pull some brush to the back...I revved up the engine to get going and noticed black smoke coming out the exhaust. It was then I realized that I forgot to push the choke knob in all the way before mowing. While I cut the grass everything seemed fine though.

While pulling the tarp, the engine did not seem to have much power, so after that, I managed to limp along at low idle and get the tractor back in the garage...

Today I dug in a little deeper to find out what the problem was. First thing I did was to pull the plugs. As expected they were all full of carbon. Next I cleaned up the plugs and checked the spark on each side. Did this with a jumper wire to ground the base of the plugs to the engine block. Got spark on both cylinders. Next I took the valve covers off to check for a stuck valve...no problems.

Next, I tried starting the engine up. It started, but was still running weak. Then, I thought to pull off a plug wire to see which cylinder may be the problem. I pulled off the left wire...the engine started and ran on the right cylinder. Then, I disconnected the the right plug wire and reattached the left. The engine did not start up. So I know my problem is with the left cylinder. Fuel doesn't seem to be a problem. This tractor was restored in 2020 but the engine was not completely rebuilt. The command engine has 1062 hours on it.

Is it possible that the left coil is weak or shorted. It may show spark with a visual test but perhaps not enough to fire up the fuel mixture. I know will have to probably pull the engine to replace a coil, but, I'm hoping that some of the helpful experts on this site, might have more insight into my engine problem.

Your ideas and thoughts on this are very much appreciated!

[ol'George]

Did you replace the bad spark plug? if not replace or swap sides and see if the dead cylinder follows the plug.
It is possible for a plug to look good. and not fire.

[Farmall450]

Originally Posted by ol'George

Did you replace the bad spark plug? if not replace or swap sides and see if the dead cylinder follows the plug.
It is possible for a plug to look good. and not fire.

Also see if any of the plug wires are shocking you; if so replace. On a newer unit, it's probably the coil, but still good diligence to check.

That stumped me for a little bit on my 982/4 (first time I've come across a bad plug wire that only caused the cylinder to die on idle).

Probably not great for the coil!

[garydee]

Thanks to the help from ol'George and Farmall450, my Kohler CH18 Command engine is up and running again!!

As suggested, I tested the wires on both sides...all ok. Then I installed a brand new set of plugs in the engine...and presto, she fired right up and ran smooth as can be!! Hard to believe that the problem was a dead spark plug. Never had this happen before...

I am very grateful for the quick and knowledgeable response from these senior members of the only cub cadets website. Great people willing to take the time to share their knowledge makes for a great website!

Again, thank you ol'George and Farmall450 for your help in quickly solving my engine problem!

garydee

[Farmall450]

Glad it's working.