# Kohler Cv16s Bacfire(miss) Need Help!



## t&t (May 30, 2008)

I have a Sears Craftsman Riding Lawnmower with the above engine in it. The engine is 16 hsp. Mower runs great but intermittent problem, every once in awhile engine starts missing/backfiring out exhaust. You can cut grass for 2 hours, and then all of a sudden starts missing/backfiring. I have cleaned carb, and checked fuel, all good. I bypassed ignition switch, and still does it. Originally regulator was heating up, and melted plug end, rewired and replaced relay. Charging normal, stator has good output, very intermittent, doesn't matter if it is underload or not. NEED HELP DESPERATE.


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## 30yearTech (Sep 14, 2006)

Possible ignition module failure when hot. I would also pull the flywheel and inspect the key and make sure it's not partially or completely sheared.


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## t&t (May 30, 2008)

It doesn't matter if the lawmower has been running for awhile or not. The fly wheel key is brand new and just been put in, still does it.


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## pyro_maniac69 (Aug 12, 2007)

is the an OHV model? if so, I would be checking the valves and see if they are still in spec


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## 30yearTech (Sep 14, 2006)

t&t said:


> It doesn't matter if the lawmower has been running for awhile or not. The fly wheel key is brand new and just been put in, still does it.


Well you indicated that you would run it for a couple of hours and then it would start acting up. I would still suspect the ignition module as what you describe usually points to intermittent spark or late ignition timing.

Why did you replace the flywheel key??


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## t&t (May 30, 2008)

30yearTech said:


> Well you indicated that you would run it for a couple of hours and then it would start acting up. I would still suspect the ignition module as what you describe usually points to intermittent spark or late ignition timing.
> 
> Why did you replace the flywheel key??


replaced flywheel key because i hit a stump while using mower. this model uses a spark advance module and an ignition mdule(coil).do you believe its whigh one? if valves were out wouldnt it act up on a more regular basis. seems like it gets worse with engine load


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## pyro_maniac69 (Aug 12, 2007)

if the valves are not correct, when it is getting hot, on valve might not be pushing as hard as the other one, or not releasing all the way, which will make it backfire, might also be a valve seat in the head going bad, whatever it is, from what your describing so far, it shouldn't be carburation, iginition possibly, but is sounds like it might be something mechanical more than anything


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## t&t (May 30, 2008)

any idea on what the specs are for the valves?


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## pyro_maniac69 (Aug 12, 2007)

I'm not sure, on a kohler I don't have any resource information on them, I normally have to call technical to find out for sure. BUT, if you have hydrolic lifters, they need to be torqued down to a specific in. lbs and they are set like that.

If you post you Model & Spec Number, I'm sure 30year could probably get that information for you


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## 30yearTech (Sep 14, 2006)

Well it really does not sound like a valve problem to me, but there is always the possibility. Did you torque the flywheel down to spec when the key was replaced? If not the new key could have easily sheared again.

Goto www.kohlerplus.com there you can download a service manual for your engine. The manual has test procedures for checking the S.A.M and ignition module as well as spec's for the valves.

You have to use internet explorer to access their site, just enter as a guest and you will find the manuals and illustrated parts lists for your engine.


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## t&t (May 30, 2008)

turns out the problem was with the unit was wired from factory. on the spark advance module there is a white wire that goes to ground when unit is turn off. this in turn kills spark to engine. this wire was multiplexed with a bunch of other safety b.s and several relays. in the kohler service manual it mentions about the problem i was having if this wire is tied in with other stuff. i isolated wire and the problem went away. thanks to all who helped.


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