View Full Version : Piece of Junk Kohler part II

09-07-2000, 01:09 AM
Nice to be back here on the site. I have been gone for a couple of weeks due to my wife giving birth to my daughter.

Anyway this Kohler 25hp is giving me more trouble and I need help before I throw it into the river. It will start and run fine and then all the sudden it will start running rough. It will pop and spit and then all the sudden it will clear up and run fine. It might run fine for two hours or two minutes, who knows? I have done everything I know to do; changed the plugs, changed the air filter, changed the fuel filter, removed and cleaned the carb, drained the gas tank, checked the compression on both cylinders. Anyone have any more ideas? I thought that it might be the coils but then I thought that if it was the coils then it wouldn't clear up once it started, would it?

Any help would be appreciated.

I would pass out cigars but that might be a little hard!!

09-07-2000, 03:11 AM
How many hrs our on it? I have a 20 hp Kohler on my Grasshopper that is doing the same thing. Mine has 2500 hrs
and has been doing this off an on for the last 500 hrs.
I was going to put a new carb on it but decided to hold off.

It uses just a little oil, but I figured it was time to replace it, so I am just waiting for it to blow up.

Let me know if you figure it out.

09-07-2000, 06:06 PM

The motor only has 350hrs. on it.


I've already changed the fuel filter and blew out all the lines and drained both tanks. What will the gas treatment do? I value your opinion so give me some more ideas.


The last time that I had a problem with this motor you solved it so chime in with your diagnosis.

09-07-2000, 06:18 PM
Kohler has problems with coils. Several serviuce bulletins out on the subject. There is a new part number that supersedes the old ones in service on many of these engines and it is my understanding that Kohler will supply the new coils at no charge, not sure if that will apply to installation or not. Also a critical adjustment in the air gap between coil and flywheel. I have two new coils sitting here for my 25 hp horizontal, now that mowing has slowed some I'll pull the engine and check numbers and adjustments and if I have the bad coils I'll swap them out. I'd be willing to bet that your problem is not fuel, it's spark. Talk to your Kohler dealer about service bulletins dealing with coil problems.

09-07-2000, 07:33 PM
My favorite subject.
My firsthand advice from someone who owned one is to get rid of it.
That said there are MANY things you can check.
1. Ignition switch.
2. Head gaskets
3. Intake gasket.
4. the dreaded coils
5. fuel filter
6. fuel pump
7. Oil pressure or head temp sensor
8. search this site for Kohler.

When all else fails with this hell motor go back to my second sentence. My first Kohler was spawned from the devil himself in 1998. I almost had more mechanic time than mow time.
Hate to be the bearer of bad news but I think some of the assembly people were working on these engines after a long night out. Good Luck.

Eric ELM
09-07-2000, 08:53 PM
Sounds like a broken wire somewhere that is making contact at times and not at other times. The only problem I've had with my Kohler is the intake manifold gasket at about 2,200 hours and I had two modules replaced at around 3,000 hours. It could be a bad module that has a bad connection too. Try cleaning all your wire plug in connections and then coat them with electrical grease to keep them from coroding. If that don't do it, you may need to have to have the dealer check the modules in it. They can check them to see if they are bad. If it only has 350 hours, it should still be under warrantee. It has a 2 year warrantee, so it can't be to old with only 350 hours. I now have 201 hours on the new diesel DC I got in June. I hope this helps. :)

09-07-2000, 10:03 PM
Might be a long shot, but if it's a ZTR, check the safty switch under the seat.May need to be adjusted.

09-07-2000, 11:47 PM
Thanks guys

I believe that the problem is probably electrical. I'll check all these things in the AM. Thanks again.

09-08-2000, 12:09 AM
My 15 kohler does the same thing.

09-08-2000, 12:36 AM
Check the safety switches

09-08-2000, 12:40 AM
I agree with Eric. Probably and electric problem. I have a friend with a little honda rider that had a similar problem. He said the mower would run fine for about 10 minutes and then quit. He would wait a minute and start it and it would run fine. He said he thought it was some electrical connection. I don't know if this helps or not, just my 2 cents. Hope this helps a little.:)

09-08-2000, 12:48 AM
I've had good luck with all my Kohlers until now. I've already replaced the Fuel filter, and used gas treatment
this really doesn't make a difference. Today it ran smooth for about 1 hr then it was all I could do to get it to stop sputering and missing. I finally got it to smooth out by only using about 3/4 throttle for a while which seemed to smooth it out then I gradually increased it too full.

It sounds like it only firing on 1 cylinder , for a while then the other kicks in and out. I 've drained my tank, cleaned the carb out thinking it was fuel, I've choked it and sometimes that helped. But now it doesn't seem to make a difference . Think I'll check out the electrical. Thanks for all the imput, I was about to buy a new engine, but I know there is another season left in this one.

09-08-2000, 09:48 AM
MJB....Mine Kohler does the same thing. It runs fine until you try to put it at full throtle, then it sputters and misses. Extremly frustrating, especially when you have tried everything to fix it. My opinion, trade it in, thats what I'm going to do.

09-08-2000, 10:25 AM

It's the SAM (Spark Advancement Module) - Their electronic spark control system.

This has been discussed before, the problem is common.

Get it replaced as the dealer. At 350 hours, it's under warranty, right?

09-08-2000, 11:26 AM
If you can afford to,try and replace it with a 26hp efi motor,they have an electronic diagnostic system on them so you can ring the dealer and get a diagnosis over the phone.


09-08-2000, 04:46 PM
<<It sounds like it only firing on 1 cylinder , for a while then the other kicks in and out.<<

That's because it IS firing on only one. Get your dealer to pull the service bulletins on this engine. Kohler has acknowledged the problem and has a bulletin to address it.

Eager Beaver
09-08-2000, 07:16 PM
Three suggestions
1. Check the oil sensor wire to make sure it is not shorting out. Also the sensor itself by unplugging it and try running it without it hooked up.Can cause a ignition defect like situation.
2. Pull the valve covers and check to see if you may have a bent valve that may not be closing all the way. Its easy just 4 bolts but make sure you put the gasket back in the groove when reinstalling.
3. Could be Kohler's "Smart Box" ignition system. I worked for Walbro Corporation who made some of these products for Kohler in the engineering dept.and it was not uncommon to have these go bad.You will have to trace manufacturing dates with your dealer to see recall dates if any.
Any finally you may have a plug in your carb by the main jet which is causing it to run lean. the engine seem to be abnormally hot. By fulling out the choke you are forcing more fuel to be pulled threw the carb and thus running richer. With a plug in this area you may need the increase in vacume to keep it running.
These are all suggestions, Good Luck,Eager Beaver

09-08-2000, 08:01 PM
About 3 month ago my lazer started cutting off and back on quickly. Sometimes 5 times on one yard. I looked under the seat. There is a connector down there that runs to the safety cutoff. Unplug that connector. Clean the prongs good. The prongs on mine were covered with dirt. All I know is it did not ever cut off like that once I did this.

John DiMartino
09-09-2000, 12:32 PM
These 25Hp problems are scaring me-I know i will have only about 300-350 hrs on mine when the warranty expires,so ill be stuck with the bill for all the problems on this POS engine.I feel real good now,I think im going to be sick now.

09-10-2000, 09:58 PM
Of all the posts I've read, I think this one has helped me the most. I WILL make SURE that the rider I get next Spring WILL have a Kawasaki engine. I've never heard anything good about Kohler.

John DiMartino
09-10-2000, 10:10 PM
My next one will be anything but a Kohler too,BTW the kawi 23hp is stronger than the 25Command anyway,cheaper too.The other benfit is its better on fuel and you dont need to rev it to 3900+to get power out of it.Peak torque on Kawi is at 2400,and it got the same torque as the 25 at 3600.I have 32 kawasaki engines in my golf cart fleet,they are 1999's.they all run daily and have about 400hrs on them now,not one has ever need oil or had a single mechanical problem of any type.In addition they are all underrated as far as HP goes,the 9hp Kawi is as strong as 11hp Yamaha.

09-11-2000, 01:18 AM
I have a 23 kaw on my laser. I have used the 25 kohler also. The kaw is a far better engine!! It runs stronger, never slows down. Hills, long grass, nothing slows it down. I will never buy another kohler engine.

09-11-2000, 10:16 AM
My 25 Kohler on my DC just blew again. Second time in a week. It doesn't help that my dealer is clueless. I know very little about engines, that's why I buy new mowers and change oil and air filters religiously. I cannot afford ANY downtime and therefore am seriously considering replacing the 25 Kohler with a 23 Kawi. How difficult would this be? Will the wiring be about the same or will there be some modifications that need to be done?

Eric ELM
09-11-2000, 10:28 AM
I'm sure you would need to change the wiring harness. I've heard the 23 HP Kohler has about as much power as the 25 HP and according to my dealer, he is switching to them and has had good luck with them. The 24 HP Honda engine is also available for the DC's now, so that could be another option.

02-06-2003, 12:26 AM
Originally posted by eslawns
Of all the posts I've read, I think this one has helped me the most. I WILL make SURE that the rider I get next Spring WILL have a Kawasaki engine. I've never heard anything good about Kohler.

Well now you have! I've used Kohlers on 4 Toro wbs and a Lazer Z hp over the last 10 years with only one failure, a $100 fix, and that mower I bought used about 6 years ago. I've actually never had to replace one yet, so I don't know how long they last. The 25hp kohler seems to be the problematic one. So don't throw the baby out with the bathwater.

That said, the Kawi's do seem to have more torque for given hp rating, so that's a plus for them.

Tony Harrell
02-06-2003, 08:32 AM
My experience with the run/don't run good thing is, it's almost always an ignition problem.