Koehler Engine Trobule

[K5krawler]

Hello All,
I hope someone can point me in the right direction with a problem I am having with a 22 HP Koehler V-twin engine. Here is the video of it running while cutting grass, the problem might not be able to be heard but the engine has a distinct miss or stumble while running at full rpms. I have already done the plugs and fuel filter, so this is leaving me to thinking it could be related to either the carb or the fuel pump. I don't want to start throwing parts at something but figured you guys might have had a problem with this type of engine and see problems with ethanol in fuel causing damage to the fuel pump or carb? The only way to get the engine to run right is either idle down or shut the mower off and then start it back up. That doesn't even always work and it seems the problem has got worse since the video.
http://youtu.be/ZzXQcuDeXOo
K5

 

[K5krawler]

Why can't I embed video??!!

 

[K5krawler]

Model CV22S

I took a few pictures of the plugs that came out when the problem first started.
Compression is 90 PSI on each cylinder.
The problem again is at full rpm the motor will start to backfire. I can move the throttle all the way to idle and let it run for a few minutes and it stops backfiring and runs pretty smooth. The carb was disassembled and cleaned this morning with no effect on the why the motor was running. I can only think of two things either spark or there is an issue with the valve train.

 

[lfnh]

Long shot, but it might be worth checking the electrical
wiring to the fuel shutoff solenoid for breaks or high resistance.

also possible the hydraulic valve lifters maybe collapsing from wear
or the wrong weight oil.

fwiw

 

[K5krawler]

Here is a video from today. You can hear the motor breaking up at 3/4 + throttle. I am going to try changing the oil as it's been a while since I've changed it. I heard this motor is picky about the oil 10w-30.[video=youtube_share;ZSeGeWfDCug]http://youtu.be/ZSeGeWfDCug[/video]

 

[lfnh]

right oil - might check kohler site for service manual

 

[brokenbudget]

by the look of the plugs, i'd take a look at the intake gaskets at the cylinder. make sure the bolts are tight and the gaskets are sealing properly.

 

[VA-Sawyer]

Try putting a DC powered timing light on the plug wire and checking for the coil breaking down. The fact that it seems to improve after a few minutes at idle points me towards the coil. Valve train or carb isn't likely to recover that quick at idle. Neither will an oil problem.
Rick

 

[K5krawler]

Try putting a DC powered timing light on the plug wire and checking for the coil breaking down. The fact that it seems to improve after a few minutes at idle points me towards the coil. Valve train or carb isn't likely to recover that quick at idle. Neither will an oil problem.
Rick

Order a spark tester to see if I can tell a difference in the spark from side to side. Maybe there is a spark plug wire breaking down causing the miss?

 

[brokenbudget]

the coil on these fire both the plugs at the same time, every time. the stumble you here is a lean stumble. either the carb isn't as clean as you think, or you have a air leak. these engines were known to leak around the lower carb mounting gasket OR the intake to head gaskets. considering the plugs are the same age and one is white-ish and the other looks slightly sooted up, i would look for a fuel related problem.
a coil only gets worse and worse while running (heat soak), it doesn't get better while idling. this is a carb or intake problem.

 

[K5krawler]

the coil on these fire both the plugs at the same time, every time. the stumble you here is a lean stumble. either the carb isn't as clean as you think, or you have a air leak. these engines were known to leak around the lower carb mounting gasket OR the intake to head gaskets. considering the plugs are the same age and one is white-ish and the other looks slightly sooted up, i would look for a fuel related problem.
a coil only gets worse and worse while running (heat soak), it doesn't get better while idling. this is a carb or intake problem.

That's what's weird. Sometimes I can cut for a good 30 minuets and be okay before the problem shows up.

 

[brokenbudget]

That's what's weird. Sometimes I can cut for a good 30 minuets and be okay before the problem shows up.

if it runs that long, chances are the carb is getting low on fuel. when you put it to idle, it gives the carb a chance to 'refill' so to speak.
either you have crap on the carb plugging it up slowly, or your pump is getting weak.
white-ish grey plugs are a sign of a lean engine. not an ignition problem.

 

[equipmentguru]

I think from my past experiences that the compression is supposed to be higher than 90 psi. You should check with your local Kohler dealer to see what the compression is supposed to be.

 

[K5krawler]

Try putting a DC powered timing light on the plug wire and checking for the coil breaking down. The fact that it seems to improve after a few minutes at idle points me towards the coil. Valve train or carb isn't likely to recover that quick at idle. Neither will an oil problem.
Rick

Order a spark tester to see if I can tell a difference in the spark from side to side. Maybe there is a spark plug wire breaking down causing the miss?

Look at my video, sure looks like the coil is bad. The other side didn't loose spark through any of the RPM range.

the coil on these fire both the plugs at the same time, every time. the stumble you here is a lean stumble. either the carb isn't as clean as you think, or you have a air leak. these engines were known to leak around the lower carb mounting gasket OR the intake to head gaskets. considering the plugs are the same age and one is white-ish and the other looks slightly sooted up, i would look for a fuel related problem.
a coil only gets worse and worse while running (heat soak), it doesn't get better while idling. this is a carb or intake problem.

My motor has a coil for each cylinder. So, when I started testing this coil it shocked the living crap out of me lol made for a funny moment!

if it runs that long, chances are the carb is getting low on fuel. when you put it to idle, it gives the carb a chance to 'refill' so to speak.
either you have crap on the carb plugging it up slowly, or your pump is getting weak.
white-ish grey plugs are a sign of a lean engine. not an ignition problem.

Here is the video with the tester. Sure looks like the coil is not firing at a higher RPM. I guess there is no way to really check the coil, I mean it did shock me when I was playing with the tester, i'd say the coil and wire are probably bad.


[video=youtube;WSH9fK1Wikc]http://www.youtube.com/watch?v=WSH9fK1Wikc[/video]

 

[VA-Sawyer]

How much is a new coil ? If it is reasonable, I would just change it.

I laughed when that other guy jumped in saying a coil won't act like that. I've only been doing this for some 45 years.

Rick

 

[K5krawler]

$50 plus shipping. I will get one here shortly. It's mighty nice having the right tools for the job. I had a free shipping thing from amazon and ordered a in/lbs torque wrench and a vacuum tester with all kinds of connections along with the spark tester. I think that little tester is probably the smartest thing I have ever bought. No need to play guessing games anymore.

-K5

 

[K5krawler]

Fired it up today with the new coil and runs good. The coil was the problem. just FYI

 

[VA-Sawyer]

Glad to hear that. I thought it sounded like a coil breaking down. The higher the RPM the faster the coil fires and the higher the voltage that is required to fire the plug. The coil heats internally to a point the thermal expansion causes the weak connection to open up. At idle it cools enough to remake the connection and it starts sparking again.

Rick