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Old 05-18-2019, 08:55 AM   #1
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Kohler 6 EOD starts than shuts down.

I recently had the generator serviced. Oil and filters were changed. After the service the generator started and ran. The shop than replaced the exhaust elbow. Once this was complete and prior to the installation of the sound shield, the generator started and ran normally. The sound shield was reinstalled and the trouble started.

The generator will start normally from either the local or remote buttons. You can see the fuel solenoid pull in. The unit runs for about two seconds and the fuel solenoid drops out. At this point the generator stops. It can be restarted and the cycle will repeat. When it stops the display indicates the "UV" or under voltage error. This makes sense as the unit never gets up to speed or has a chance to produce voltage.

The local Kohler guy was called and he replaced the control board. This did absolutely no good. It has been going on a month and things are still not fixed. Now they are telling me that the "back end" of the generator has to be replaced. This is going to be big bucks and I do not think that it is going to fix things.

I am no generator expert but I have worked with electrical equipment for over 45 years and what I am hearing makes no sense.

I believe that something happened to the wiring when the sound shield was reinstalled. It has since been removed and the problem remains. I am having trouble understanding the short run time prior to shutdown and the error indication. It is my understanding that all of the error sensing circuits are inhibited for 10 seconds on startup. This will allow the unit to come up to speed and the output to stabilize. If this is true, why does the unit shut down within two seconds?

Replaceing this generator is not in my budget so I really could use a bit of help here.
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Old 05-18-2019, 09:35 AM   #2
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Does the generator have it's own battery?
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Old 05-18-2019, 10:08 AM   #3
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WDBox,

I just went through something similar on my Kohler 8CCO. It would start, but not stay running. On my genny there is a 10A in-line slow-blow fuse located inside the control box. Check that first. I ended up replacing my control board also, which helped, but I had a quick-blow fuse in the box, and it would pop when shutting down.

It seems that if it was working before all the servicing, that whoever serviced it should figure out what's happening. I feel your pain. Keep us posted on how it works out.

Cheers, Bill
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Old 05-18-2019, 04:58 PM   #4
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I have that same generator and have collected a bunch of documentation on it, including the service manual. You can find it here:
-- https://drive.google.com/drive/folde...5Z?usp=sharing

I thought that the voltage test should be inhibited by 10 seconds, also. But, since the controller board has been replaced, my next best theory is that the test is more sophisticated than I understand and may be shutting down sooner in some cases. For example, it may allow a "brown out" from an overload for 10 seconds before shutting down, but may shut down much faster for a bigger problem, such as an output-side short that holds the voltage to 0 or something much closer. So, unless given reason to do otherwise, I'd start debugging the undervoltage situation.

In my mind, the most likely suspects are the rotor, stator, and/or SCR module. But, there are other things it can be, e.g. exciter, rectifier, etc. The service manual gives the test procedure for all of these things.

If it were me, I'd make a quick check of the fuses, in particular the ones off of the auxiliary winding, sometimes called the alternator or power fuse. Then, I'd check the cheap and easy possibility -- the SCR module, which regulates the voltage.

From there, I'd sigh, and follow the test procedure outlined in the manual from start to finish to turn up the problem in a systematic way.

I'd really try to go through the full process patiently, rather than throwing parts at it. The most likely parts are probably the rotor and stator. They are expensive and would be a waste if neither is the problem, or the real problem is just the wiring to or from one of them, etc.

Good luck1
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Old 05-19-2019, 07:35 AM   #5
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The generator has a dedicated start battery. However, there is a switch that allows it to be started from the house batteries also. The problem is the same, regardless of the battery selection.
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Old 05-19-2019, 07:49 AM   #6
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Kohler

I had one do the same thing in a boat sold years ago. I gave a huge discount at the point of sale due to the on going issue with the genny. Don't remember what the issue was but I can tell you the service we got both of us from the manufacturer was far from good. I won't ever buy again from them.
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Old 05-19-2019, 08:59 AM   #7
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Most Kohlers will shut down if AC output is not detected. Could be a fault in volt reg or stator/exciter. Basic troubleshooting will narrow it down. Unlikely to be due to fussing with sound box.
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Old 05-19-2019, 12:19 PM   #8
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“If you hear hoofbeats, don’t expect zebras.”

Look for the simplest explanation, you had the filters changed, fuel supply; there is likely air in the system. Bleed it and try again.

Check that they put the oil back in, it will shut down for no oil pressure.

Marina mechanics frequently get it wrong.
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Old 05-19-2019, 06:56 PM   #9
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Stator

It was that part. I forgot the name but then read that previous post.
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Old 05-19-2019, 07:21 PM   #10
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Generic guidance... Verify the trips for coolant temp, oil pressure, and exhaust temp are working properly. A bad sensor can give you your indications. Its easy to knock a wire loose fooling around with a sound enclosure. Most gens have some sort of trip bypass while the engine is starting up. Sometimes just when the start switch is held. Some more sophisticated. Bad sensor or wire and the engine shuts off when the Start switch is released.
Does the engine shutdown coincidental to any switch movements? Is it repeatable with the time varies or exactly to the second the same?
BTW, a generator back end is going to cost around $2K without the install labor. I would have to ask exactly what indications they have that make that diagnosis the correct one. A lack of output voltage alone is not good enough. Many simple things can cause that.
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Old 05-19-2019, 07:29 PM   #11
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Quote:
Originally Posted by wdbox View Post
I recently had the generator serviced. Oil and filters were changed. After the service the generator started and ran. The shop than replaced the exhaust elbow. Once this was complete and prior to the installation of the sound shield, the generator started and ran normally. The sound shield was reinstalled and the trouble started.

The generator will start normally from either the local or remote buttons. You can see the fuel solenoid pull in. The unit runs for about two seconds and the fuel solenoid drops out. At this point the generator stops. It can be restarted and the cycle will repeat. When it stops the display indicates the "UV" or under voltage error. This makes sense as the unit never gets up to speed or has a chance to produce voltage.

The local Kohler guy was called and he replaced the control board. This did absolutely no good. It has been going on a month and things are still not fixed. Now they are telling me that the "back end" of the generator has to be replaced. This is going to be big bucks and I do not think that it is going to fix things.

I am no generator expert but I have worked with electrical equipment for over 45 years and what I am hearing makes no sense.

I believe that something happened to the wiring when the sound shield was reinstalled. It has since been removed and the problem remains. I am having trouble understanding the short run time prior to shutdown and the error indication. It is my understanding that all of the error sensing circuits are inhibited for 10 seconds on startup. This will allow the unit to come up to speed and the output to stabilize. If this is true, why does the unit shut down within two seconds?

Replaceing this generator is not in my budget so I really could use a bit of help here.

Re: "The shop than replaced the exhaust elbow..."


The exhaust elbow has an over-temperature sensor installed on it. I would check the over-temp sensor circuit. Electrical connections have a funny way of failing right after a mechanic touches them...kind of a 'reverse midas touch' IMHO.
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Old 05-21-2019, 06:57 AM   #12
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I had the same issue on my Onan QD Jenny. It turned out to be a low AC output running 6% low. Check for good water flow and proper oil level. Might be just a coincidence it happened right after a repair. Keep an open mind!
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