Help!!! Kohler Command 20 Running Rough

abeckler

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Hey guys I’m new to the forum so I hope I’m posting in the right spot.
I bought a Lincoln Ranger 8 Welder Generator with the Kohler CH20S Engine. It only has 61 hours on it, when I bought it the owner said it had just been sitting in the back of a shop and hadn’t been run in 7 years. So I drained the tank completely and “rebuilt” the Keihin Carburetor with a new o-ring and gasket set and cleaned it out. Put a can of sea foam in the tank and got it to start running. It runs rough and super rich. Sounds like it might have a knock, but it only does it every once in a while... I got a new air filter and changed the oil with Royal Purple full synthetic 10w-30. New fuel filter. No changes what so ever. Changed the spark plugs and they were carbon fouled pretty bad. It sounds like the engine is missing. And I noticed that if I pull the spark plug wire on the cylinder opposite of the starter, the engine smooths out and sounds like it’s running great. So I thought it may be a spark issue. I replaced the ignition coil on that side with no change, I rewired the coils all the way back to the ignition switch thinking it may be a wiring issue. I used steel wool on the mounting surfaces for the coils thinking it could also be a grounding issue and also ran an auxiliary grounding wire... still no change. The good cylinder has 175psi of compression and the side that is missing has 172psi... so I'm completely at a loss. I’ve also tested for a leak on the intake gasket with no luck.... I’ve read that it could possibly be a blown head gasket but I don’t see how that could be it with only 61 hours.... maybe a valve issue? But I pulled the valve covers and roatated the engine and they’re opening and closing as they should be. My only other thought is possibly a timing issue? Maybe the magnet on the flywheel got bumped and moved somehow? I really don’t want to take the damn thing into a shop... any input, advice or solutions would be greatly appreciated! Sorry for the long post. I just wanted to get everything out there that I could.
 
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No post is too long at all .......... Unless it's jibberish and yours is not jibberish...........

Be careful how you rewire those coils ...... Briggs engines have diodes and those stop any voltage going to the coils and frying them to a crisp .........

The PSI readings are both good and healthy...... If you had a bad head gasket then your reading on 1 of them will be lower.......

Did you actually check for spark before you threw money at a new coil ???? In line spark testers are a must ..... Oregon has the best ones... It's a red neon type and you can see the spark in the daylight easily ... I have 2 of them myself...

www.amazon.com/Oregon-42-031-Spark-Tester-Engine/dp/B0000AXCOV

Let us know Mon Ami ~!~!
 
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Ok 1 reason I asked you about spark is that you have way more electrical stuff on that engine than most older truck engines do LOL ........

You have schitt in between such as a rectifier and a voltage regulator.... On some engines the coils will be good and the other is no good... So a service manual on that engine will do you justice....

There are a few Techs on here that put up manuals for guys like you that need one .......

So they will chime in when they see this thread.....

Plus Tard and Joyeux Noel Mon Ami ~!~!
 

abeckler

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I guess I should have added that one reason I went for replacing the coil was that when I would pull the wire on that side while it was running it would shock me. Yet the other side wouldn’t do that. So I was assuming that the wire was grounding out somewhere and wasn’t creating a spark or at least not a strong enough spark. And I was going to try and just replace the wire but these engines have the wire built into the Coil. So I figured it wasn’t super expensive to replace and it was a good place to start. And I looked up the manual for the engine as well as the manual for the specific welder that I have which both included wiring diagrams before I went and just started replacing wires lol. The diagram shows a single wire that goes straight from the ignition switch to the coils and it makes a Y to supply both coils with a constant power off of the same line. I don’t have the spark testing lights, but I “tested” them the old school way by grounding the spark plug out while cranking the engine. And I thought that the spark looked a lot weaker on the affected side... but then I did it again after it got dark and I could see the arc a lot better and it had the same amount of spark on both sides from what I could visually see from my very unscientific test :laughing:
So from everything I’ve done, I’m back at square one... and I’m 99% sure that the rectifier/regulator is bad. But I don’t see how that would affect spark or timing or especially not just on one cylinder...
 

ILENGINE

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that knock could be a hydraulic lifter acting up, or sometimes they will get a groove worn on the bottom because they failed to rotate, We were laughing about the lifters the other day in my Kohler update class, because the new owners manual talks about the lifters making a pinging sound sometimes, and it is normal and if it doesn't go away in 20 minutes go see your dealer. That ping they talk about sounds like the rods are coming out of the block.

Boudreaux In Eunice La. Be careful about the results you get with the blink testers on the Kohlers with the CDI ignition because they will give you a false positive. They will show spark when the module is failed, but if you use the correct high energy tester they will fail. Kohlers also have the talk back diodes built into the modules, so they don't have the diodes in the interconnect wire like the briggs..

I suspect that if the engine has set for 7 years there are some passages that are still clogged. For example if an air bleed is clogged it will cause a rich run issue.
 

abeckler

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So basically there’s no way to physically tell without pulling the head and inspect the valves to see if they are improperly worn? I just have a hard time believing that there is something horrendous wrong with it such as valve issue or a blown head gasket like I have read on other threads due to there only being 61 hours on the machine... how would I go about inspecting or trying to unclog the passages that you’re talking about? And what do you mean by an air bleed?
 
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He means the carb is not clean all the way...... When we hear someone on this forum say they cleaned the carb then we take it that it's not all the way clean......

Did you clean it in a Ultra Sonic cleaner ???? That will bust the schitt out of that carb and tiny passages.... 7 years of setting up equals a nasty carb in most cases..........

So if the carb isn't clean then you foul your plugs.........
 

Rivets

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To throw a real monkey wrench into this problem I’m going to suggest something off the wall. After cleaning the carb, did you check you governed top speed? Generators and Welder Generators need to have both their load and no load speeds set to spec, to ensure that they have the proper electrical output. You don’t say whether the engine runs rough with and/or without a load? There should also be a no load solenoid hooked the the governor and must be hooked up properly. Just a thought, which may be as dumb as it sounds, but I would check.
 

ILENGINE

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Won't hurt to dump a couple ounces of seafoam in the oil and run it, then change it after a couple hours. The seafoam will clean out the oil passages in the lifters, which could fix the knock issue. The air bleeds are gets and passages that mix air with the fuel as it gets drawn through the jet if the are clogged will cause the engine to run rich. The jets on the air cleaner side of the carb, as well as the holes in the side of the emulsion tube are part of the air bleed system.
 
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