Onan 5000 GenSet only runs with start button pushed in

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gman93012

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Hello, I need help …

I’m having a problem and I hope you can guide me in the right direction.

My Onan 5000 GenSet Generator on my 1999 Winnebago Adventurer WAS working great. Now it won’t stay running.

After some time I tried starting the generator and it wouldn’t start. Battery is good. Fuel Tank is full.
It cranks and starts but as soon as I release the start button it shuts down.
I checked the oil and it was pretty low. I added oil and It still doesn’t start.
I gave it a tune up replacing the spark plugs, the Fuel Pump and Filter. The air filter.
I went as far as changing the Start Button/control board assembly.
I also unplugged the plug that connects the two start switches in the coach. Isolating those switches.
It still does the same thing, shuts down after the start button is released at the generator itself.

In reading your website’s suggestions.
I think it might be my Oil Level/pressure Switch.

Can you please assist me in locating the Oil pressure switch?

Thank you very much!
Gerard Frensdorff

Copied from another website ...

Reasons Why Your RV Generator Runs Then Shuts Off?
• In earlier gensets, a burned out resistor caused that symp¬tom.
• However, since the evolution of electronics, it can now be caused by
o A faulty oil pressure switch
o A faulty voltage regulator
o A failed control board
• The Onan Marquis requires sufficient oil pressure to keep running, so carefully check the oil level.
• If it is correct, then it may be a faulty oil pressure switch, or it could also be stuck in the open position.
 
If you have a multi-meter on hand, check to see what voltage the generator is outputting while you hold the button in to keep it running. The controller needs to see 65-70 volts at a minimum to lock in the run circuit. If the generator has been sitting for quite awhile, the slip rings may have tarnish built up on them. Again, holding the button in to keep the generator running, see if the voltage starts to rise slowly. If it does, that's a pretty good indicator of dirty slip rings. Flight Systems makes a tool for cleaning the slip rings that's pretty easy to use. If no voltage at all is being generated, then it'll take deeper digging.

 
In my case with my 4000 model the control board was the cause of the non- continue run but my regulator was also wonky causing higher than normal voltage.
From what I learned it sounds like your field is not getting flashed which as mentioned hopefully is only a slip ring resistance issue.

Quick check is to ohm the slip ring leads at the board connector (unplugged)
anything 30 ohms or less is good.

See my journey...... Onan 4000
 
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As I recll there is a sensor near the oil filler with a single wire.
That is the oil pressure switch.
NY-Dutch also cited another issue.. The onan, if there is no output. will shut down (why waste fuel if I'm not making power).

I have actually seen this one year at Quartsite.. Thankfully they were parked next to the only live (even if only part time) 30 amp outlet in the desert.
 
Have you checked the error codes? At the genny, if the light brinks three times, press one time to the left (prime) fast and count the lights in two digits. You must use the switch on the genny itself. It has the red light.

What it means when it dies when you let go, is that the control board is doing its job of shutting down the genny for various things being wrong, such as output frequency too high or low, voltage out of range, etc.

Get the trouble code before you do anything. And post it here.

And see here. BTW, some older models do not show the codes. But even this Y2k RV has them.

I am assuming your 1999 does also.

-Don- Tom's Place, CA
 
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NY_Dutch said:
If you have a multi-meter on hand, check to see what voltage the generator is outputting while you hold the button in to keep it running. The controller needs to see 65-70 volts at a minimum to lock in the run circuit. If the generator has been sitting for quite awhile, the slip rings may have tarnish built up on them. Again, holding the button in to keep the generator running, see if the voltage starts to rise slowly. If it does, that's a pretty good indicator of dirty slip rings. Flight Systems makes a tool for cleaning the slip rings that's pretty easy to use. If no voltage at all is being generated, then it'll take deeper digging.

Click to expand...
He likely won't be able to use the tool to clean them due to access issue. The generator would need pulling for that. That rarely is ever the issue. The periodical running of the generator is an old WWII lay over. Electronics have come a long way since then.

It is either...

1. Voltage regulator
2. Oil pressure switch
3. Control board
 
udidwht said:
He likely won't be able to use the tool to clean them due to access issue. The generator would need pulling for that. That rarely is ever the issue. The periodical running of the generator is an old WWII lay over. Electronics have come a long way since then.

It is either...

1. Voltage regulator
2. Oil pressure switch
3. Control board
Click to expand...
An Onan 5000 in a 1999 motorhome is most likely a BGE, and using the Flight Systems slip ring tool is really quite easy to do without pulling the generator. The electronics have come a long way, but 20+ year old slip rings still tarnish causing poor contact with the brushes.

Here's a video that shows how its done:

 
udidwht said:
Electronics have come a long way since then.
Click to expand...
Except for the Onans, which are still an ancient design.

udidwht said:
The periodical running of the generator is an old WWII lay over.
Click to expand...
It's mainly so moisture doesn't accumulate on the armature and stator. Running under load until warm for a while also helps get moisture out of the engine oil and other stuff.

-Don- Reno, NV
 
DonTom said:
Except for the Onans, which are still an ancient design.


It's mainly so moisture doesn't accumulate on the armature and stator. Running under load until warm for a while also helps get moisture out of the engine oil and other stuff.

-Don- Reno, NV
Click to expand...
Even Onans have come a long way in terms of it electrical components. Most of the electrical tidbits are packed away such that moisture isn't an issue. I've never seen a generator issue solely related to moisture.
 
gman93012...Did you ever get your problem solved?

Where are you located?

I know a guy in Fresno who will come to your house, etc to work on a Onan generator in this local area.
 
DonTom said:
I would be the control board is doing its job. If there is an error code, that will prove it.

-Don- Tom's Place, CA
Click to expand...
Hey DonTom on a 94 blounder do you know if it is capable of running the error codes? Ran into a little issue today and at this point it's truly pissing me off as it is 2 AM eastern standard time. Rebuilt generator and all is going well there, reinstalled back of the RV and it looks to be a little bit of modification on some of the wiring considering the fact that it had 12/4 house wire inside the generator cabinet. Due to not knowing what that mess was all about we pretty much dead ended it for a moment until we have time to track it down but here is our actual symptoms if you will........

Generator has been reinstalled back into the RV. RV has the appropriate amount of gas, everything else has been checked out, even replace the fuel pump when I tried to tell them that it needed gas lol, sorry I couldn't let that go ha ha ha. We were able to prime for 15 seconds and we are able to press and hold the start for five. genie but will start when you release the start button generator will immediately die. Unfortunately while we were there later this evening I did not bring my little fancy multi digital checker thingy LOL. but I am really leaning toward the voltage regulator. I do believe that the control panel is doing its job by shutting it off due to an inappropriate amount of voltage. Do you know where the voltage regulator is on that generator or the RV itself? my next question is do you have any idea of where the box for the 0NON would be inside of the RV to where it can be primed and started from inside? I have looked everywhere and I have been unable to find it. The only button inside the RV that pertains to the generator is on the actual dashboard just right of the key switch . So basically my questions come out to this do you know if 94 is able to run the Error codes? Do you have any idea of where the voltage regulator is and whether it's on the generator or the RV and do you know where the inside box unit is that starts the generator itself? What are the odds that the voltage regulator would be down or do you think it's a possibility as a slip rings needed to be cleaned?
 
DonTom said:
Welcome. I see this is your first post here.

It's probably too old for the error code light thingy, but to be sure, post here the model number of the generator.

-Don- Auburn, CA
Click to expand...
onan emerald + and I believe its a 5000 if I remember right but its been a long day. I will double check first thing at daylight.

I do apologize for the light level of smarta$$ery (error code light thingy) and (multi-digital thingy) but you see I am a woman and have been dealing with 3 mechanics, granted that had to call me in this morning, because they don't deal with any kind of small engines lol. It was a absolute headache and almost a knock down drag out fight when I tried to educate them that the RV had to have fuel since it was on a 1/8th of a tank. according to them and a hour of cranking, the fuel had nothing to do with it!!! the gas station was directly across the two lane highway. I am happy to say that it started Immediately. I really wasn't joking bout the pain in my buttocks part, because when it comes to actual troubleshooting id rather it just be my hands and everyone else kindly leave. Thank you, this is my first post here, I normally don't have this kind of issue and im certain I have found the majority of this ol gals issue! you seemed by your comments to be fairly familiar with this generator so I thought Id reach out. as of now, I've narrowed down to aux battery, voltage reg, and rings.
 
Onan generators are designed so that they will shut down when the starting switch is released if there is no 120V out of the generator. The 12V sustem that supplies power to the starter also supplies all of the control system until you release the switch but when you release the start switch the engine side then only recieves power from the output of it's generator and will stop if the generator is not working.
 
Kirk said:
Onan generators are designed so that they will shut down when the starting switch is released if there is no 120V out of the generator. The 12V sustem that supplies power to the starter also supplies all of the control system until you release the switch but when you release the start switch the engine side then only recieves power from the output of it's generator and will stop if the generator is not working.
Click to expand...

100% agreement to this.

Also, regarding your question of inside rv control, it was normal in that era to only have the start switch on the dash.
I added a second one at the sink area and also a remote key fob operated relay to start it remotely.
 

"AL Bradford", If you have 2 ACs on the roof, you have an Onan 7K NHM. If 1 AC on the roof you have an Onan 4K BGE. Neither one is capable of error codes. Both turn at 1800 RPMs. 2 of the quietest gas Onans used in RVs.​

Richard
 
House Husband said:

"AL Bradford", If you have 2 ACs on the roof, you have an Onan 7K NHM. If 1 AC on the roof you have an Onan 4K BGE. Neither one is capable of error codes. Both turn at 1800 RPMs. 2 of the quietest gas Onans used in RVs.​

Richard
Click to expand...
You left out the 5K BGE. I have one, and it runs our two roof top A/C's just fine.
 
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