Onan Not Staying Running October 29, 2017, 07:59:43 pm Hi all, I have an Onan 4000 that is on a 1992 RB unit we recently purchased. The previous owner stated it had not worked in years and they never used it. I changed oil and filter, cleaned carb and checked plugs. The unit started right up and runs very smooth.....only when you hold the start button (both outside and inside). If you release the start button, it immediately dies. Any thoughts?.....Maybe I am not thinking of something.Thanks so much, Paul
Re: Onan Not Staying Running Reply #1 – October 29, 2017, 08:03:18 pm I would google 1992 Onan 4000 troubleshooting forums, use different key words and you might find some suggestions....one search I found allot of information
Re: Onan Not Staying Running Reply #2 – October 29, 2017, 08:09:54 pm Quote from: TigerRE - October 29, 2017, 08:03:18 pmI would google 1992 Onan 4000 troubleshooting forums, use different key words and you might find some suggestions....one search I found allot of information Thank you. I was trying to avoid the never ending google search and see if anyone here has had had a similar issue.
Re: Onan Not Staying Running Reply #3 – October 29, 2017, 08:38:35 pm A quick look at the LDO search engine reveals 67 pages of Generator data. While your answer may not be immediately revealed, this will give you plenty to read while someone comes to your rescue. Off the top of my head I vaguely recall that the generator gets it’s starting power from the chassis battery so you may want to check the health of that item and move forward from there.Wish I could be of more help.Kent
Re: Onan Not Staying Running Reply #4 – October 29, 2017, 10:28:39 pm I recently had a similar issue with my onan 4000 and after hours of googling and cleaning every orifice I could, I ended up installing a new carb and all is well. These things cannot sit very long without getting gummed up and mine would act in the same manner you’re describing before the new carb. Hope that helps. Scott 1 Likes
Re: Onan Not Staying Running Reply #5 – October 29, 2017, 10:49:39 pm I wondered about that because of her long hibernation. I just thought it odd that it runs so well until you release either switch. Thanks so much, Paul
Re: Onan Not Staying Running Reply #6 – October 30, 2017, 02:27:38 am A modern Onan will quit when the starter button is released if it is not producing a 115 volt AC output. I don't know about the 1992 version. You need to chase down the service manual and trouble shooting guide for your model.It could also show that symptom if the carburetor is not passing enough fuel to keep running. Squirting gasoline into the intake can answer that question. If it runs then the carburetor is at fault.A long hibernation could put an oxide layer on the slip rings which will lead to failing the voltage regulator which will lead to no AC out of the Dynamo. Try the simple things then take it to an Onan service center if you don't want to drop and disassemble it yourself.Harry 2006 RB
Re: Onan Not Staying Running Reply #7 – October 30, 2017, 10:05:13 pm As mentioned above, the generator will stop if it does not sense the proper output voltage.My 96 had some issues and eventually all led to the voltage regulator not working, thus shutting down the generator.Couldn't hurt to check to see if output voltage is correct.It's not good to keep your finger on the button too long, but you should sense voltage output fairly quickly to check it.I wore out my starter doing this so be careful. 1 Likes
Re: Onan Not Staying Running Reply #8 – October 30, 2017, 10:57:01 pm Thanks so much for the insight! I will check the carb fuel as well as looking into how to check the voltage regulator. Thanks so much, Paul
Re: Onan Not Staying Running Reply #9 – November 01, 2017, 01:53:15 am You can also polish the slip rings of an older Onan without taking it apart. If the voltage regulator is bad you probably need to do that.It is called a slipstick from Generator & RV Controls Repair and Replacements, Engine Monitoring, Idle....Harry 1 Likes
Re: Onan Not Staying Running Reply #10 – November 01, 2017, 10:36:16 am I bought a voltage regulator from Flight Systems ( much cheaper than Oman and lifetime guarantee) and replaced it myself with very little problem. My genie would start and run until I put any load on it. It would then quit immediately. It may only need slip ring polishing tho. I would try that first. Utube and Fight Systems have instructional videos. Dale.
Re: Onan Not Staying Running Reply #11 – November 01, 2017, 06:38:39 pm Dale, the one in our o7 MidBath would die under load. It was a issue with the little fuel pump inside the generator compartment. The issue is not talked about much on this forum but over on RV net it is a more common topic (relatively speaking). 1 Likes
Re: Onan Not Staying Running Reply #12 – November 02, 2017, 09:32:55 pm Thanks for the info on flight systems. I have gone through a few troubleshooting guides and have an appt. tomorrow but it does look like the slip rings are the issue.Thanks so much, Paul
Re: Onan Not Staying Running Reply #13 – November 03, 2017, 11:31:47 am Please keep the group updated?
Re: Onan Not Staying Running Reply #14 – November 03, 2017, 08:08:36 pm Wow....Flight Systems is amazing and is highly recommended! After watching the videos and reading their troubleshooting guide yesterday I was pretty sure what the issues were. Even though, I booked the phone call service to see....Yes, phone call service!! They have an online booking for phone call service.....you book the date and time on the website and they call within the hour (Eastern time).I booked for 1:30 and the call came in within 30 minutes. I talked with Tom and he asked multiple questions and had me test certain connectors and we determined that it was either slip rings needing cleaning or a voltage regulator. He wanted me to try cleaning the rings first before I ordered anything. I also asked about the slipstick and he said it would be quicker to clean with emery cloth to determine the problem. He also asked my opinion about the videos as they are fairly new and they have not had a lot of feedback. This company is Top Notch, very willing to help and is offering a great service!Once I took off the cover it was obvious the rings needed cleaning, so I did so but to no avail. I am now thinking it is the regulator that may have quit years ago but the previous owners just did not use the generator so it was never repaired. I am ordering one tonight and will see how that goes and will let you know.Paul 3 Likes
Re: Onan Not Staying Running Reply #15 – November 04, 2017, 02:24:16 am Quote from: pjh4064 - November 03, 2017, 08:08:36 pmOnce I took off the cover it was obvious the rings needed cleaning, so I did so but to no avail. I am now thinking it is the regulator that may have quit years ago but the previous owners just did not use the generator so it was never repaired. I am ordering one tonight and will see how that goes and will let you know.Unfortunately, the only way I know of to test a Onan control board is with a Factory tester, something only an Onan service center is going to have. From you description of the symptoms, the control board is the most likely candidate.Let us know how it works out.Larry
Re: Onan Not Staying Running Reply #16 – November 04, 2017, 07:19:11 am Just throwing this out. I have no idea if this diagnostic is on an Onan 4000. The lights on the starter buttons (inside and outside) on a 2007 genset will flash three times if the genset shuts down. You then get the Onan manual and find how to use the lights. The number of secondary blinks is a reason code. I will not try to reproduce the manual, but if your getset quits and you see three blinks, find the manual and decode the blinks. 1 Likes
Re: Onan Not Staying Running Reply #17 – November 04, 2017, 09:50:37 am Larry,The control board is separate from the regulator correct? Where is it located? He had me check ohms at the 9 and 10 pins from the plug. He said if the reading was high and jumped around when turning over, it was either the rings or the regulator (They have a great video on the website that walks you through this troubleshooting procedure). Before I polished the rings it was very high and it jumped all over when turning over the genset. Once the rings were polished, the reading was in the normal range, but still jumped around when turning over. I am hoping this is it, otherwise I will have many new parts that I don't need to worry about for quite some time:)! Thanks so much for the help, Paul
Re: Onan Not Staying Running Reply #18 – November 04, 2017, 04:58:57 pm Quote from: Larry W - November 04, 2017, 02:24:16 amUnfortunately, the only way I know of to test a Onan control board is with a Factory tester, something only an Onan service center is going to have. From you description of the symptoms, the control board is the most likely candidate.Let us know how it works out.LarryLarry, now you have me second guessing myself and I did not think you were able to test the control board either, but here is what I found out The troubleshooting guide is from the flight systems website and I would suggest anyone to have it on hand as a print out. It has a complete breakdown in order as well as cross reference for all Onan gensets connection pins for the regulator and control board for testing. I read again through the troubleshooting guide and started at the top: 1. I was able to determine with multi-meter through the control board connector pins (for my model) that there was no AC voltage once running (meaning either control board, regulator, or slip rings).2. The control board field flash pin (again for my model) read right at 11.6 VDC during cranking which was within the 10-12 range (meaning now either regulator or slip rings).3. The regulator field circuit pins (again for my model) now have the correct reading of 26 ohms after I cleaned the slip rings (meaning lastly that the regulator is likely defective).Now, this sounds complicated and trust me, I did not think I could or was even able to do all of this (even with quite a bit of mechanical aptitude), but it was quite simple. The only issue I had was having to cut back the silicone a bit on the control board to be able to confidently apply the multi-meter ends to the correct pins. Once I am done, I will seal again.We are 3 hours away from any service center so for me to be able to do this is great now, and also when we (or anyone else) is traveling and has issues. Again, hopefully I have pinned it down and let me know what you think, Paul 2 Likes
Re: Onan Not Staying Running Reply #19 – November 09, 2017, 09:20:36 pm Done Deal!!! I received the new voltage regulator today. Installed and plugged it in and what do you know...the beautiful continuous running sound of a generator even after I removed my finger from the switch! I checked load and all is well. As discovered after the testing previously posted, the control board was fine. Hopefully this helps someone else.Thanks so much, Paul 4 Likes
Re: Onan Not Staying Running Reply #20 – November 09, 2017, 11:14:16 pm Quote from: pjh4064 - November 09, 2017, 09:20:36 pmDone Deal!!! I received the new voltage regulator today. Installed and plugged it in and what do you know...the beautiful continuous running sound of a generator even after I removed my finger from the switch! I checked load and all is well. As discovered after the testing previously posted, the control board was fine. Hopefully this helps someone else.Thanks so much, PaulPaul, thanks for letting us know the solution to your problem. Chris 1 Likes
Re: Onan Not Staying Running Reply #21 – November 10, 2017, 02:11:35 am Quote from: pjh4064 - November 09, 2017, 09:20:36 pmDone Deal!!! I received the new voltage regulator today. Installed and plugged it in and what do you know...the beautiful continuous running sound of a generator even after I removed my finger from the switch! I checked load and all is well. Paul thanks for providing an endingQuote from: pjh4064 - November 09, 2017, 09:20:36 pmDone Deal!!! I received the new voltage regulator today. Installed and plugged it in and what do you know...the beautiful continuous running sound of a generator even after I removed my finger from the switch! I checked load and all is well. PaulThanks for letting us know the outcome to this problem. I learned a few things.Flight Systems is a useful find, it should save a few of us a lot of money, with its accessible and knowledgeable troubleshooting information. Larry 1 Likes
Re: Onan Not Staying Running Reply #22 – November 10, 2017, 12:44:25 pm Your experience echoed mine to a tee. It's great when, with a little research and experimentation, you can be successful in repairing something. It's a great feeling of accomplishment, not to mention the amount of money you saved. Flight systems is a great resource and they guarantee their parts. Their customer relations department is great also. Thanks for sharing your experience! I'm glad you are now able to use your gennie, too. Dale from Downey.
Re: Onan Not Staying Running Reply #23 – November 10, 2017, 12:52:46 pm It took me awhile to get to the voltage regulator when fixing mine.After so many diagnosis and testing tries, mine needed other work just get it to run at all.Then, with the help of a knowledgeable friend, one who does not give up and has excellent electrical skills,narrowed it down to the voltage regulator.I was so happy to have my gennie back, after three years of frustrating attempts at getting it going.This is now the third or fourth story I've seen that the voltage regulator has been the cause.Maybe something to note in the archives for future help with these things.Glad you have it fixed ! 1 Likes
Re: Onan Not Staying Running Reply #24 – November 10, 2017, 01:16:07 pm Good to know. I have never heard any shop repairing one without replacing just about everything.Ours threw a code and quit after running 45 minutes. I forgot to capture the code. On another day I ran it 2 hours and it worked fine. 1 Likes
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