This is all on a Kohler 25 Command series Model CH25S
Hey guys me again thank you on the input, i have it narrowed down to the coil, but i would like to go ahead and swap out everything beings i am there and have it all taken apart can someone fill me on the pros / cons of going with the Spark advance over the 18 HP coils or vice verse. Also Autogatemen if you see this please chime in or anyone else that has done this, how do you swap out to the 18HP coils without spark advance? Do I have to change the ignition system also or is it just a plug and go operation. Trying to also find out part number for it can't seem to locate the part number associated with the model on opeengines.com

Rectifier please explain this to me and what its job is, when would one swap one out mine is 16 years old?

What spark plugs does everyone use someone told me it doesn't matter but i have a friend that recommends E3?

And the oxygen sensor why wouldn't that be plugged in, I bought this motor 14 years after it was made so plenty of folks have had their turns on her.

Thanks everyone again for helping.

ok first, the coils are available at any lawnmower shop. You just unplug everything connected to the smart spark, mount the new coils, and hook up the kill switch wire to the spade terminal on top. this will be a wire that is grounded when you pull the kill switch lanyard.

second, use any good plugs, its a lawnmower engine.

rectifier changes the AC output of the stator to DC to charge your battery. dont mess with that unless your batteries not being charged.

oxygen sensor?? theres not one on these, not sure what youre talkin bout. if youre referring to the plug by the carb that is not plugged in, thats a fuel shutof valve that is disconnected because your motor wont start if the battery isnt hooked up (i.e. you want to just pull-start it)

you can pm me if you have anymore questions

How did you narrow it down to the coil? Just curious. I told you something to try on the first thread, then you jump to another, then I ask you a question, now your talking about o2 sensors and charging systems. Just slow down for a minute...

Getting rid of the smart box may help you, but if that's not your problem, it ain't gonna fix it.

As already stated in a previous thread, you can go to the 30 coils which retain the spark advance, but don't have a box. They run off a 12 volts and automatically advance based on rpms, similar to the "box" but a better system...To install you cut the box out, swap the coils, hook up the white wire auto mentioned, and 12v....

You can just replace the box with a newer version...Or if the box is good, you can just replace the bad coil. The service manual tells you how to test it.

Or you can go with the 18 coils. A simpler swap. Swap in new coils, hook up white wire...Biggest advantage, you get rid of the box, but if you don't need to, you don't need to.

The new cdi (briggs) motors have a built in spark advance. Advancing the timing a lil bit can be a good thing. It is a minimal timing advance and picks up with engine rpms, so not quite the same as a timing key, but similar logic. You can still use a timing key also...

As auto said, any local dealer should have the 18 coils in stock. There is a seller on ebay named duffstorm that sells both the 30 and 18 coils if you cannot find them locally.

Before you start purchasing parts though, make sure you've isolated your problem. Not saying you haven't, but you haven't posted how you came to your conclusion the the coil is bad, and now your posting about stuff that is totally irrelevant to the coils and some things that do not even exist on your motor. Just don't get in a hurry...Take your time make sure you fix what's broken and don't get ahead of yourself.

I still haven't seen the answer to the question, "are you getting spark?"

Thanks bomb tech and auto for the info, sorry I rambled about several things.here is a recap on where I am at and again I will stay with the same post here on out on the same subject.

Took wires off each side tried to start and right cylinder wouldn't start. So spark plug was fine, checked to see if plug wire had fire. No spark from plug wire so I am assuming its the coil or plug wire beings the left cylinder is fine. If left cylinder was having issues I would say it might be spark advance (which I am sure it still could be the spark advance bc there are wires that run out independently to each coil)let me know if that is accurate. Have not done any test on coil because I don't know how to check it? I am thinking if coil doesn't fix it then it must be spark advance. The other questions came about during taking everything apart to get to it.the green wire I found that goes into the top of what looked like a sensor its by intake I saw in the service manual. So the fuel shut off is what it is nice, lol. I was a little off to say the least, thanks for the clarification. Thank you again and let me know how far off you think I am on this one.

Some motors won't start on only cyl 2, mine won't. It will on 1 but not 2 for some reason. Pick up a spark checker and check that way, or remove the boot from the plug, stick a screwdriver in the socket, hold it close to the block and turn the motor over, you should see a small spark. Check both sides just to make sure. Oh, and don't be touching the metal on the screwdriver when you do it or you'll get a nice zap.

If that checks out, download the service manual for your motor off the kohler website (should probably do that anyway and read it a few times). There is detailed instructions for testing the "smart box" in the manual. If its bad, go from there. If not, we'll start looking at other things.

By the way, I have a working box and set of coils if you determine that's the problem for sure. Could save you some coin unless you just really want to upgrade. I was recently cleaning up the wiring and didn't like the box so I upgraded to the new 30 coils to get rid of some clutter. Been on the motor since 04 and never had an issue with the coils or the box.

Replaced coil, motor now runs on both cylinders! Last night while running it seemed my fuel pump was running more than before could this be if the ground was not grounded very well. Also I did not hookup the green wire to the fuel cut off, had a brain fart and didn't label if it was hooked up or not during disassembly. It seems as the motor idles higher now than before could that be the new coil compared to the old coil? Also it seems more gas was going in the carb than before could that be related to the green wire hooked to fuel shut off or the fuel pump not being grounded very well? My brother took it out this am so I am waiting to here a report of what happened under a load. Thanks again.

Glad you got it fixed. You can adjust the idle. I'd turn it down to just above stalling out when you drop the prop in the water.

Its been confirmed the fuel pump is running more than before i believe its due to a bad connection on the ground wire does this sound right? I am going to fix the connection tomorrow, well see if that fixes it.

You added an electric pump? The stock pump runs off vacuum. If you added an electric, then I guess it's possible. Bad grounds do wierd things, wouldn't think it would make the pump pump more though. If you added an electric, you may try just taking it out and see how the motor runs without it. If you don't have any air leaks in line, you shouldn't need it.

Yeah sorry I didn't clarify you mean ur not a mind reader? Same pump that was on it previously. Just now it seems to pump more when even when it is primed. Which them floods motor while idling when wide open it fine but so much fuel is going through you can smell fuel getting all the way out of the motor it is extremely rich due to pump working to hard.