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Kohler Magnum 20 Not Starting.


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#1 Lauber1 OFFLINE  

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Posted August 24, 2014 - 04:31 PM

I have one of these in a Craftsman tractor and it wont start. Mostly it backfires or doesn't try to fire. I've cleaned the carb, reset the plugs, check the spark leads, have it running off a nurse fuel tank, have unhooked the kill wire,  checked the flywheel key, but if I do get it running it acts like the choke is full on or that its only hitting on one cylinder. I cant figure it out, so anyone else had something similar to this happen.


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#2 JDBrian OFFLINE  

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Posted August 24, 2014 - 04:56 PM

What do the plugs tell you after it quits. I'm thinking you may be running on one cylinder as well. Do you have good snappy blue spark? 



#3 Lauber1 OFFLINE  

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Posted August 24, 2014 - 05:13 PM

the plugs look kind of wet and dark. haven't checked the spark at the plug, just with my test lead, and the light flashs pretty good. went to the kolher site, and found some thing to look at. one was the carb setting and the other is an oil pressure sensor. Its hot out today so I might not get back out there right away.  Man I telling you this aint no Model N brigg or Clinton, they are easy to work on.



#4 Bruce Dorsi ONLINE  

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Posted August 24, 2014 - 08:46 PM

Jeff:

 

I had a Kohler M18 drive me crazy for awhile with similar symptoms.  

 

Problem turned out to be a warped carb flange where it bolts to the manifold.  ....You can not use two gaskets on this carb flange !!

 

I flattened the carb flange on abrasive paper on a flat surface, and checked the manifold flange for flatness (that was OK).

 

I couldn't believe how sensitive this engine was to the warped carb flange !!

 

There was also something which I had never encountered before.  ......If I tried checking the spark with both plug wires off, I would not get any spark.   .....One wire had to be connected to a plug (or tester) in order to test the other wire's output.  .....Checking one cylinder, then the other, confirmed both cylinders were firing.

 

Once the engine was running properly, I started using the stump grinder it powered.  .....It ran great for awhile then started miss-firing & stalling.   .....When the stump grinder cut down to a certain level, the engine was tilted enough that the low-oil-cut-off was activated.  .....Over-filling the crankcase slightly solved that problem, with proper running since then. 


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#5 Lauber1 OFFLINE  

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Posted August 24, 2014 - 09:25 PM

well I went out an double checked the needle adjustment of the waboro? carb, it was fine, found there is no low oil switch. Cranked on it for a while and it would fire and kick the starter out, then it would start and run poorly. I reached down under the shield and found the left side exhaust pipe was cold, so it must not being firing on that side. didn't have an extra #26 plugs, so i'll go the cheap route tomorrow and get a new pair of them. after that its going to be a new coil.


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#6 superaben OFFLINE  

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Posted August 24, 2014 - 10:38 PM

well I went out an double checked the needle adjustment of the waboro? carb, it was fine, found there is no low oil switch. Cranked on it for a while and it would fire and kick the starter out, then it would start and run poorly. I reached down under the shield and found the left side exhaust pipe was cold, so it must not being firing on that side. didn't have an extra #26 plugs, so i'll go the cheap route tomorrow and get a new pair of them. after that its going to be a new coil.

 

Most Magnums like good plugs, and they get picky when the plug isn't just right  I use RV17YC on the twin Magnums that visit me. 

 

The coil usually doesn't fail on one side only, it is a single electronic coil with two leads.  However, if one of the spark plug wires are damaged, it will act like it is not working right.  I can sell new ones for $75.  I am out of stock, though, as of tonight. 

 

Ben W.


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#7 Lauber1 OFFLINE  

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Posted August 25, 2014 - 07:32 PM

its just too dang hot here tonite to work on toys. I got a pair of plugs to try, and if I need a coil i'll look your way, as the price is good.



#8 Lauber1 OFFLINE  

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Posted August 27, 2014 - 08:51 PM

Got the tractor running and mowed with it last night. All it took was a new pair of  plugs.  Found out after wards that it don't have any brakes, and the steering doesn't go as far to the right as to the left, but other than that its a pretty good machine. The best part was the FREE on the price tag.


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