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Old 09-10-2017, 07:59 PM   #1
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Suddenly Generator problems

Suddenly Generator problems in our new us to 2015 Citation 29TB

Our generator will immediately shut down when the AC is on and I start the Microwave with a # 13 error code.
A couple of times while testing, the gen will keep running but stops when the micro finishes with a # 12 error.
Here are the voltages I see.
119 with nothing on
118 with just the AC
115 with just the micro
108 with both running

Because ALL voltages are low I'm guessing that the control board is bad.
My biggest problem is I can't find any part #'s for Onan.

Any and all comments/links will be greatly apperaciated!

More info
Gen is a QG4000 with 129 (7 are ours) hours, I have no idea if any maintance has been done, I've changed the oil.
All voltages are in the normal range when on shore power.
Other issues, I temperally fixed our hot skin condition by unhooking the bad wire and reconnecting the neutral wire in the breaker box.

Thanks ab&jb
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Old 09-10-2017, 08:41 PM   #2
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You are probably maxed out on amps. One appliance at a time. Not good for any appliance to run on low volts as well.
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Old 09-10-2017, 10:29 PM   #3
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I had a similar problem with the same model. I also bought mine second hand and it had very low hours. It turned out to be the carb. The previous owner apparently didn't use stabilizer and let it sit for months at a time. You can try a Seafoam treatment(Google it) to see if that works. Seafoam can occasionally perform miracles. If it doesn't, change the carb and get it over with. The carbs can not be rebuilt and you must buy a new one. If you shop you can find one for less than $300. You'll need your exact model number and serial number to get the right one. It's not a complicated job but it's really tight in there and it's tough for a man with big hands. Ask me how I know. Once you get it going, use stabilizer and exercise it for an hour a month under a moderate load. YouTube has a ton of videos on this problem.
By the way, the voltage is not as important as the frequency. The controller board is generally happy between 58 and 67hz. If you vary from that the genny will shut down. When you put a heavy load on it and the rpms drop so does the frequency. When you remove that load the engine will over speed and frequency will go too high. The genny will shut down to protect your appliances. A gunked up carb can cause this to happen.
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Old 09-11-2017, 02:41 AM   #4
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Originally Posted by jim5554 View Post
I had a similar problem with the same model. I also bought mine second hand and it had very low hours. It turned out to be the carb. The previous owner apparently didn't use stabilizer and let it sit for months at a time. You can try a Seafoam treatment(Google it) to see if that works. Seafoam can occasionally perform miracles. If it doesn't, change the carb and get it over with. The carbs can not be rebuilt and you must buy a new one. If you shop you can find one for less than $300. You'll need your exact model number and serial number to get the right one. It's not a complicated job but it's really tight in there and it's tough for a man with big hands. Ask me how I know. Once you get it going, use stabilizer and exercise it for an hour a month under a moderate load. YouTube has a ton of videos on this problem.
By the way, the voltage is not as important as the frequency. The controller board is generally happy between 58 and 67hz. If you vary from that the genny will shut down. When you put a heavy load on it and the rpms drop so does the frequency. When you remove that load the engine will over speed and frequency will go too high. The genny will shut down to protect your appliances. A gunked up carb can cause this to happen.
The carb is high on my list, the motor surges a little, the volts swing between 119, 117, 119 within about a second.
The mh sat on the dealers lot at least all winter.

My #1 suspect is the controller, because the gen ran SO smooth for the first few hours. I didn't notice anything when I looked it over when I changed the oil.
I noticed the crack in the controlled as soon as I took the cover off to work on the low voltage problem.
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Old 09-11-2017, 03:38 AM   #5
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The controller was my number 1 suspect also. The genny started right up and ran great while I had a load on it. The minute I put a full load or removed the load it died. How could it possibly be the carb? I did some research and found an Ask the Mechanic website for Onan generators. I'm not a newbie at this and I've been rebuilding carbs for almost 50 years. The symptoms and the solution ran counter to my experience. The mechanic insisted it was the carb and he was right.
The crack in the circuit board will only be a problem if it goes through copper traces. They usually don't put them that close to the edge of a large board.
Epoxy the crack to keep it from spreading and try Seafoam. It's cheap and you might get lucky. You can try replacing the board, they're cheaper than a carb, but I think your wasting your time.
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Old 09-11-2017, 05:11 AM   #6
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You might find these two links of use:
1) Parts Manual
http://trekdocs.com/Onan%204000%20Parts%20first43.pdf
2) Maintenance Manual
www.rvwithtito.com/download/Onan4000MaintenanceManual.pdf
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Old 09-11-2017, 02:10 PM   #7
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A surge protector is a great investment. It will show you volts, amps, hz, any any error codes. May save your electronics if the campground pedestal happen to be wired wrong.
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Old 09-11-2017, 04:47 PM   #8
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Quote:
Originally Posted by jim5554 View Post
You might find these two links of use:
1) Parts Manual
http://trekdocs.com/Onan%204000%20Parts%20first43.pdf
2) Maintenance Manual
www.rvwithtito.com/download/Onan4000MaintenanceManual.pdf
THANKS

I've been looking for these for weeks!
I went to your link and downloaded the rest of the parts. Onan seems to be protective of their info.

I'm on my way for more SeaFoam, I keep a can for cars, but 1 isn't enough. Thinking about taking the cab off and soaking it in some carb cleaner.

ab&jb
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Old 09-12-2017, 01:31 AM   #9
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Don't pull the carb out unless you're going to change it. It's really tight and the throttle and choke plate are easily damaged. I bent the choke plate when I was pulling my old one out. It didn't matter to me because it's only good as a doorstop anyway. If I was just going to soak it I would have been screwed.

Here's a link to a YouTube video from Seafoam explaining the whys and hows. It's aimed at a Onan Marquis 5500. It's similar but not identical;



Here are detailed instructions for the QG 4000:



Google and YouTube are your friend.

Good Luck
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Old 09-12-2017, 02:45 AM   #10
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Originally Posted by abjbrtd View Post
THANKS

I've been looking for these for weeks!
I went to your link and downloaded the rest of the parts. Onan seems to be protective of their info.

I'm on my way for more SeaFoam, I keep a can for cars, but 1 isn't enough. Thinking about taking the cab off and soaking it in some carb cleaner.

ab&jb
If you register at Cummins Quick Serve, you can download all the manuals you need.
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Old 09-12-2017, 03:51 AM   #11
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jim5554

It's looking like the seafoam is working! It starts easer, runs smother and I'm getting a steady 120v.
I ran it 3 times for a total of .6 on the hr meter.

I cleared the error code and sure enough the next time I hit the ac...it died.

more run time tomorrow
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Old 09-12-2017, 06:14 PM   #12
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By the way, I forgot to mention this. Have you checked the altitude setting on the carb? That can cause some strange problems including a lack of power.
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Old 09-12-2017, 07:24 PM   #13
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We usually travel between TX 800, FL 0 and CO +7000 every summer.
I change the altitude at least 3 times a year.

I found the oil level the most critical thing to monitor on our last mh. Let the oil get 1/2 to the add mark and we would have shut downs while driving on rough (aren't they all) roads.
Didn't have that problem this year no point in running the generator.
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Old 09-13-2017, 12:19 AM   #14
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I'm by no means a super generator expert but I've been using and working on small generators since I was in the Army That was 49 years ago and I can pretty much fix anything. They really aren't a heck of a lot more complicated than a lawn mower or a tractor. Most of the parts are easy to swap in and out. You can troubleshoot them most of the time with simple tools and a decent manual. These Onan RV QG 4000's are the fussiest, flakiest machines I've ever had to deal with. The new Onans require constant maintenance and attention. They're potato chip gennies at caviar prices and I'm tired of fiddling with them. They always seem to break the day before you're planning to use them. The prices for replacement parts make you think you're fixing a Maserati. This has to stop.
I wish the RV Manufacturers would go to something more dependable, like a Honda or much cheaper, like a Champion. With any luck someone like Champion will design a unit that drops into a bay designed for the Onan and sell it at a reasonable price. I'd buy it in a minute.
Rant off

The altitude adjustment was just a thought. I do most of my driving at or near sea level and rarely touch it. Keep dosing it with Seafoam. Sometimes it takes more than one treatment and it sounds like you might be making progress.
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Old 09-14-2017, 12:24 AM   #15
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Originally Posted by jim5554 View Post
By the way, I forgot to mention this. Have you checked the altitude setting on the carb? That can cause some strange problems including a lack of power.
Any tips on exactly where the altitude setting adjustment is at, or what it looks like?

ONNAN 4000 unit here...
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Old 09-14-2017, 01:16 AM   #16
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Here's a small video showing the adjustment. It's the black plastic lever by the yellow label in the center of the video. You adjust it with the engine off.

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