Kohler Command 20- Power Loss/Won't Throttle Up

13 years ago

I have 1992 Toro Proline Groundsmaster 120 52" mower with a Kohler Command 20 engine. Although I am not a engine guru, I have meticulously maintained this mower and it has around 1000hours. Any here is why I am looking for help

Last fall on the second to last cut for the year my mower just decided it wouldn't run at full throttle after a short break in mowing. Basically it was running fine when I went in to take a break but when I came back out, it started fine but simply wouldn't go at full throttle when I moved the throttle lever forward. It sounded like it was idled up but just not where it needed to be. I decided to drive it for a bit and then all of the sudden it kicked in and was fine for the rest of the mowing.

Fast forward to the last cut of the season. It started fine once again but would not run at full throttle again and no matter what I did, I could not get it to throttle up. I checked the linkage and it seems fine, though I am not exactly sure what to look for. I do have all manuals and parts list, which should be helpful. Anyway, I don't know if it an electrical issue or mechanical and am hoping someone might be willing and patient to try and help.

Not sure if this is worth mentioning but about 1 week before I started having the problem, I sprayed Fluid Film (non conductive) in about every orifice that looks like it could use some lubrication. Don't know if this may caused any sort of electrical contact problem.

If someone is willing to help I was able to clean a spot in my garage to work on it this winter and hopefully get it going before spring.

As thing are right now I have drained all fuel and will be getting a new fuel filter this week. From all the post on this site it sounds like I should be focusing on fuel issues such as cleaning the carb, making sure the lines are not clogged, check fuel etc..

Sound like a plan? Any suggestions?

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Comments (10)

tomplum
13 years ago
Engine #s could help. I don't know if this unit is the right age to have a carb with an accelerator pump on the side or not. I would remove the airfilter housing and reinstall the carb nuts. That way, you will have access to throttle linkage and such. MAy want to look down the carb throat and determine if the screws in the throttle plate are secure.
mhog
Original Author
13 years ago
Thanks for the reply. I wish I had checked this earlier when it was still light outside. I will check the numbers tomorrow afternoon and post the information. I will also take a few pictures (pictures always help me). I do think it has some sort of accelerator pump as the fuel line goes into something right after it comes out of the fuel filter.
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mhog
Original Author
13 years ago
Engine # are as follows:
Model: CH20QS
Spec: 64556
Displ: 624
Serial: 2507515727

What do you mean by re-install the carb nuts? I did look down the carb and all looks good. I have tried to attach a picture of the engine with throttle linkage and I believe the accelerator pump.

Here is a link that might be useful: {{gwi:126892}}
tomplum
13 years ago
On yours all you need to do is remove the entire airbox assy and you can run it easy enough to see a bit more to aid in troubleshooting. Yours won't have an accelerator pump. What you see is the fuel pump. Kohler does have sevice manuals online at no cost. When you change your fuel filter, "run" the line and catch some fuel in container so you can look for water and debris. Once that is done, run the line from the fuel pump into a container and crank the engine over to see if it is pumping a fair amount of fuel.

Here is a link that might be useful: Kohler
mhog
Original Author
13 years ago
I have already drained the fuel and ensured the fuel is good. I also removed the airbox assembly and filter and ran the engine, I can see the fuel coming in as it runs. It runs fine and will throttle up a bit but just not what it should. Could it be a clogged jet?
mhog
Original Author
13 years ago
Thanks for posting the link to the service manual. It will be a huge help. Will be looking at it again tomorrow late morning.
tomplum
13 years ago
In a nut shell, if you can't manually use the throttle shaft and get full throttle- that would make one think that it is starving for fuel. So, if what I am hearing is that is what is happening- delve into the carb and give it a stern cleaning.
mhog
Original Author
13 years ago
I never did make room in the garage and it is getting really cold and nasty outside now. This will have to wait a few days till the weather cooperates.
mhog
Original Author
13 years ago
Ok, finally was able to look at this again today. I am able to throttle it up a bit more using the throttle linkage but still does not go up to where it should.
Cleaned the carb out pretty well and still no luck. My manual shows that my main jet has a solenoid. Could the solenoid not be functioning and causing it to not rev up? Getting pretty close to taking it to a pro.
mhog
Original Author
13 years ago
Just an FYI- The problem was a bad ignition coil for the rear cylinder. $50 fix but lots of time wasted. Thanks for all the input though.