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Discussion Starter #1
Hello. I recently bought a Woods 36" Commercial walk-behind mower that has a 12.5 Kohler Command engine on it. The problem is that it isn't very easy to start (recoil start only) and most of the time it wont start at all on CHOKE or full throttle, but if you move the throttle to the slow position (about 1/4 throttle or 1/3rd throttle) it will start in one or two pulls of the rope. Then it needs a few seconds to warm up before moving it to the full throttle position. If you dont wait, it will stall. It will also stall, even when warm, if you move the throttle all the way to the "idle" position.

Its very strange. I've never had an engine that wouldn't start on choke. I've had some that would ONLY run on choke when the carb got dirty, but never one that was the opposite.

It runs awesome after it starts, has tons of power and doesn't use very much gas at all. I can mow about 3 hours on a gallon of gas, and thats after some of it spews out (fuel cap leaks, hit a bump, go around a corner, etc, and fuel sloshes out. Got to find a new cap for it, but its a WOODS tank, not a Kohler tank so parts aren't as easy to find)

Anyone have any idea what might be wrong with this thing? I replaced the spark plug with no change.

I will say that this thing sat for probably 2 years without being started and all I did was drain the old gas and put in fresh. However if the carburetor was dirty, I would think it would run lean, and only start and run on choke, not the other way around. Also, if the carb was making it run rich, and causing it to run TOO rich with the choke on, I wouldn't think it would sip fuel the way it does. Thats why I am stumped. I very very rarely have to have help in fixing anything engine related, be it on a car, or a small engine, but this, as well as my little Honda GX390 that wont maintain engine speed under load, are the only problems I really haven't been able to fix without getting some other opinions.
 

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Is the throttle working the right way? When you go to idle, its actually moving the linakes ot idle, and when you push it to choke, its actually choking?
 

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I'd have to look, but i am sure that it is. When its running if you move it to the choke position it will start smoking and the engine loses speed. Acts just like its on choke...
 

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Sounds like you may have partially clogged holes in your emulsion tube in the carburetor. Drop the carb, clean it all up, carefully run a wire into all the holes, be sure to remove the jet, emulsion tube, pilot jet...everything that can be removed, and clean it.
 

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Discussion Starter #5
Sounds like you may have partially clogged holes in your emulsion tube in the carburetor. Drop the carb, clean it all up, carefully run a wire into all the holes, be sure to remove the jet, emulsion tube, pilot jet...everything that can be removed, and clean it.
I'll have to take it apart and clean it. My experience with that tho, is that it never fixes it. I've cleaned the heck out of Honda carbs that had obvious issues (like only running on 1/2 choke) and on one Briggs and no matter how much I took it apart, soaked it, sprayed out all the passages, jets, etc.... i could never get them to work right and always ended up with a new carb.
 

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Discussion Starter #6
I take that back - I did get one Gx160 carb to work decently after cleaning it 2-3 times. And I got one briggs carb to work right. But still had 2 hondas that had to have new carbs and one briggs that had to have a shop clean the carb. That made me ill - I never have to have anyone else work on stuff for me. LOL!
 

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I dont even use carb cleaner, I do about 10-12 a week. I use compressed air, some welding tip cleaners...and then final blow out with brake parts cleaner.

I run about 95% success rate on cleaning, only time I have to replace is when an internal passage is plugged (rare) or there is physical damage like a broken float hanger or stripped threads.

The trick on these Kohler carbs is to make sure you get the emulsion tube out...just cleaning the main jet wont get it done.
 

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Discussion Starter #8
I dont even use carb cleaner, I do about 10-12 a week. I use compressed air, some welding tip cleaners...and then final blow out with brake parts cleaner.

I run about 95% success rate on cleaning, only time I have to replace is when an internal passage is plugged (rare) or there is physical damage like a broken float hanger or stripped threads.

The trick on these Kohler carbs is to make sure you get the emulsion tube out...just cleaning the main jet wont get it done.

I'll have to look for some welding tip cleaners. I planned on going to the farm supply store today and never made it. They have lots of welding stuff there.

Do you know any way to identify what model the engine is? Its a Kohler command 12.5 from about 1990. Thats all I know. The sticker that I believe contained the model info fell off before I bought the mower. I always end up with crap like that. Ahh!!
 

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First commands were like mid 1993.

If its a Vertical shaft, its going ot have the model prefix CV, if its a horizontal shaft, it will be CH.

12.5hp means the model number is CV12.5

However thats all moot if we dont know the spec number. Are there ANY stickers on the engine anywhere? Looking for a number between 1900 and 1942
 

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Discussion Starter #10
First commands were like mid 1993.

If its a Vertical shaft, its going ot have the model prefix CV, if its a horizontal shaft, it will be CH.

12.5hp means the model number is CV12.5

However thats all moot if we dont know the spec number. Are there ANY stickers on the engine anywhere? Looking for a number between 1900 and 1942
Well, I assumed its a 1990 model - pretty sure the engine is original. The owners manual for the mower has an October 1990 print date on it. Although I suppose the manual could have been printed before the machine was made, IDK. It only specifies that the engine is a 12.5hp Kohler - it doesn't say what model or anything like that in the book.

I'll look for a spec number again closer but so far I haven't seen anything like that anywhere.
 

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I checked, it could be original, Its the Horizontal and vertical V-twins that came out in the early 90's, the Singles came out a couple years prior.
 
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