Kohler carburetor problem

Trevans

Member
I have a Kohler Command 20 on a ZTR mower, the carb leaks fuel, so I ordered a kit and rebuilt it, (new needle and seat etc.) It still leaks. I proved it is the needle seat, because with the fuel bowl off if I raise the float with my finger it will shut off and not leak, although I seem to have to raise the float all the way. The float is entirely plastic including the tab that rests against the needle, so not adjustable.

I have rebuilt more carbs than I can count, but this has me baffled. Also, I can't imagine what the electric wire is going to the base of the bowl is for. Maybe a miniature solenoid, but what does it act on?
 
As for the float level, take the carb off, turn it upside down with the bowl off.

With the float and needle valve in place, the float should sit parallel to the bowl gasket surface. If it is sitting low, something is wrong in the length of the needle, or the wrong seat. Compare the original parts to the new carefully.

If it sits level, could be trash in valve, or the needle or seat is damaged. Examine it closely, clean it thoroughly. It only takes a tiny speck of trash to hold it open. If the tank is contaminated, it will get trash in the needle valve again. As a final test, hold the body upside down, suck on the fuel fitting and hold your tongue over the hole. If it won't hold vacuum, it won't seal gas.

As for the solenoid... When the ignition is turned on, you should feel the solenoid click. When the solenoid is energized, the main jet is allowed to flow fuel. When the ignition is off, the solenoid stops fuel from flowing through the main jet.

The reason for this is 2 fold. If the ignition is cut off with the engine up to speed, it prevents the engine from "dieseling" or trying to run on even though the spark has been killed.

It also stops unburned fuel from passing through the engine as it coasts down. That prevents the unburned fuel emissions, and prevents muffler explosions.
 
Steve, Thanks for the hints, which I have used some of in the past. I will admit to doing something I traditionally have not done, I trashed the original parts prior to insuring the rebuild was satisfactory. Mistake on my part. What I am sure of is the cleanliness of it all. I may have to use two fiber washers under the seat. I have a lot of spare carb parts, mostly car & truck. Maybe I'll get lucky and find what I need.In any case I'll do as you suggest.
As for the function of the "solenoid valve, thank you. makes sense.

How I ended up with multiple posts I have no idea, they appeared after I tried to edit which I was not allowed to do.
 
I'm surprised that that you got a new seat in the kit. Most kohler kits just have a new needle and if your seat is damaged you are out of
luck.

How did you get the old seat out? You pull straight out-no twisting. If you twist it, it can put a spiral groove in the body like a thread
and the O.D. of the new seat won't seal the groove up when you press it in.

If you are sure the new seat is in there right, you can sometimes improve the seal of the new needle by lapping the new seat with valve
lapping compound (Fine grit) on a Q-tip.
 
T.R.K. Again, good advice. Maybe I thought there was a seat and there was not. Hmmm, got me wondering. Thought I remembered a fiber washer, if so, there was a seat. I'll try the lapping if appropriate. Thanks.
 
T.R.K. Again, good advice. Maybe I thought there was a seat and there was not. Hmmm, got me wondering. Thought I remembered a fiber washer, if so, there was a seat. I'll try the lapping if appropriate. Thanks.
 
Wire should be going to a solenoid that cuts off fuel at shutdown. This is to prevent backfires which will take the head gasket out. Believe me that's not such a fun repair but if you search for that repair on Google it will surprise you how much content there is out there.
 
(quoted from post at 20:23:00 04/13/19) T.R.K. Again, good advice. Maybe I thought there was a seat and there was not. Hmmm, got me wondering. Thought I remembered a fiber washer, if so, there was a seat. I'll try the lapping if appropriate. Thanks.
o seat, apparently I was not getting enough sleep and remembered wrong! Anyway, the needle and seat looked perfect, and when I turned the carb upside down, the float was level with the casting. But not being satisfied, I took a miniature o ring (.100 od and .050 id and stretched it over the post on the end of the needle. Correction, my wife did this part. When positioned over the small id and down as far as possible, it takes up the"slack" when the needle is slid on the float. Clear as mud, right? The effect is that the needle will seat with slightly less fuel in the bowl. I took a pic, but it is getting late and may post it next time. In any case I'll see how it works tomorrow.


As far as a new carb goes, $35 is cheap enough for sure, but I feel defeated if I can't repair something! Old habits are hard to change after 78 years.
 
My repair with the O ring to limit the fuel level seemed to have worked fine. It ran like a new one with no longer having a fuel leak. It sat all day with no leak, but at the end of the day started a slow drip. Defies logic. Mine anyway. I will win this battle at some point!
 
(quoted from post at 20:13:33 04/16/19) My repair with the O ring to limit the fuel level seemed to have worked fine. It ran like a new one with no longer having a fuel leak. It sat all day with no leak, but at the end of the day started a slow drip. Defies logic. Mine anyway. I will win this battle at some point!
tarted mower today, sounded fine, idled well. So I ran it outside and mowed some grass for 20 minutes or so. It ran great and no fuel leak. Go figure... Maybe the needle and seat decided to be friends.
 
Sometimes a needle and seat can throw us a curve ball. I fiddled around for two years trying to get a needle and seat to seal on a zenith carb. I tried a different needle and seat, new seat gasket, I lapped, I tapped on the needle to try to seat it, I tapped harder, I tried different float levels, the float wasnt catching on anything, both floats were the same level and then all of a sudden out of the blue it sealed up. Evidently I was more stubborn and won out!
 

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