Kohler Command 25s hard to start and loss of power under load

[KKMZKA]

Hi all,

I have a Woods zero turn with a Kohler Command 25s engine. Very recently, I have to crank the motor over for atleast 5 minutes before it will finally stay running. It coughs, pops and sputters. Once its running, it runs "normal" until I engage the blades. Then it typically dies or caughs, pops and sputters. Eventually, I am able to get the blades engaged and can cut the lawn at a slow pace. If I try to go too fast, the load causes the engine to sputter and want to die. The following are the engine details:
Model No. CV25S SPEC NO. 69536 Family: YKHXS.7252GC
After reading some suggestions from other posts, I did the following: Once the engine was running normally, I pulled the spark plug wire from one plug and it kept running (a little bit of change). I re-plugged in the first one and repeated the same on the other side. There was no difference between the sides on one cylinder.
I have also performed the following with no success of resolving the issues: rebuilt the carb, replaced the plugs, replaced the fuel pump, fuel filter and the fuel lines. None of these has helped.
Can anyone provide any suggestions? I am pretty handy but I have no idea what to try next...

Thanks!!!

 

[mechanic mark]

How does air filter look? If gas is old, drain & install fresh high octane 93 gas with fuel treatment. https://www.lawnmowerforum.com/threads/john-deere-fuel-treatment.56774/#post-343220
https://www.google.com/search?q=sta....0l7j69i60.17789j0j4&sourceid=chrome&ie=UTF-8

Free Kohler Service Manual Downloads - OPEengines.com

Listed below are Kohler engine service repair manual in Adobe PDF format that you can download for free. Below we have provided a link to these manuals which can also be download. Click on your engine listed below to download. These service manuals provide general information, adjustment...

www.kohler-engine-parts.opeengines.com

scroll down page to CV25 & click, Service Manual for your engine, answers to your questions plus specs. for your engine & how to repair.

 

[bertsmobile1]

Either you have lost a cylinder or the governor is not working as it should or both

 

[gainestruk]

You said unplugged one cylinder and it had a little or a noticeable change, on the 2nd did it do exactly the same with a noticeable change ?
If you don't have a compression gauge you can take sparkplugs out and put you thumb over hole on one cylinder spin engine with starter it should blow your thumb off hole, do other side and see if the same, all this does is tell you there is compression or not, you can get a cheap compression gauge at Walmart, Harbor Freight etc. try this and get back to us.

 

[KKMZKA]

Hi all,
thanks for the replies... sorry it took me time to reply but I lost this post!!! Got it bookmarked now...
@mechanic mark - The air filter is very clean. And the gas is fresh - I never store a mower with gas in it over the winter... and it ran just fine early this spring/summer until recently.

@bertsmobile1 - how do I check to see if it is a cylinder or governor?

@gainestruk - when I unplugged the spark plug wire on one side, the engine rpms dropped a very little bit but kept running. The symptoms were the exact same when I replugged in the spark plug wire and did the same on the other side... in other words, the engine sounded the same no matter which side was unplugged. I do not have a compression gauge but I guess I will buy one.. ugh! I did buy two spark testors and tried that yesterday... the lights on both sides looked very bright and steady when the engine was running at full throttle.

Question - if it is a compression issue, will the engine need to be replaced?

Thanks again for all of the help!!!

 

[KKMZKA]

I just ordered a compression gauge... it will be here tomorrow so I should be able to post the cylinder pressure numbers tomorrow. What should the readings be?

 

[bertsmobile1]

You have wasted your money
You need to do a leak down test.
Compression tests are meaningless because they will vary with the amount of valve lash due to the decompressor

You check for a dab cylinder by removing a spark plug.
You test for a bad governor by manually moving the governor shaft,