Onan 2500 - no AC power

[OldPilot]

07 Roadtrek Agile SS. Onan 2.5KV Propane. The generator starts just fine. But now it does not come online as in the past. About 20 to 30 seconds after it starts you can hear the generator 'bog' down intermittently. This sounds like it is trying to connect but cannot.

I just don't know where to start diagnosing. I don't know if this is a gen motor problem or an electrical problem. It's not easy to crawl under the van, but if I do I don't know what I need to look for.

It did start and operate normally about 2 weeks ago when I ran it with a load from turning on A/C and the microwave. But that time was one successful time after having noticed this symptom a couple of times before.

This may be an issue where I will have to go to a 'generator place', but I would like to have a clue about what is going on before I do go.

[OldPilot]

I was able to get the gen to connect today after making the original post. The generator died twice after a few seconds of running with intermittent slowdowns which I think was the generator trying to come on-line. Finally, after trying to get it started and online with various configs like connected to shore power or engine running, the generator run seemed to smooth out. Still no connection. I turned it off then back on again. Timed it up to 1 minute without it coming online. I decided to just let it run. It was smooth with no exhaust smoke like it had before. After a few minutes it did connect. Since it was going good now, I turned on A/C heat strip and used microwave to heat water to put load on generator. It ran for 20 min or so until I turned all off.

I don't know if this is a fix or just a warning for the future. Still don't know what is going on.

I did open generator access door and was able to start from below. I could not see anything else down there to manipulate. It's hard to do much since the Aux Battery lies just in front of the access. Not sure how much maintenance I could do with battery box blocking some of the opening. (I would appreciate a comment from other RT owners who have similar configs about how they perform any maintenance.)

I will let things cool down some and then try to bring the generator online and see if all works normally. I'll report later.

[OldPilot]

Well...I'm embarrassed. It's the PD5100 Automatic Transfer Switch circuit board. How that board can be an intermittent problem is beyond me. When I talk to the PD folks maybe I will understand.

I checked relay coil..it was good. I verified I had 121v AC from generator to ATS. I manually engaged the relays while generator was on and produced AC power in the coach. So the trouble charts say replace circuit board. Cost at PD is $24. That's good --- a lot cheaper than dropping the generator.

[rowiebowie]

Thanks for the update.

Was the switch at the power center (fuses & breakers) or at the shore power connection?

[OldPilot]

PowerDynamics 5100 under seat in back adjacent to inverter/charger. In a brown plastic box. Haven't figured out how to get circuit board out of there without breaking plastic yet. Have to call PD after lunch. Supposed to be easy, but beyond me still. Board is on order from them, 2-3 days maybe.

[SQUASHMIRE]

so new board installed? any change in generator problem you were trying to fix?

[OldPilot]

Originally Posted by SQUASHMIRE

so new board installed? any change in generator problem you were trying to fix?

Well, I am both confused and embarrassed. since after Thanksgiving I have been able run the generator and had the ATS make the AC connection while still waiting for the circuit board part to arrive. I am now pondering possibilities for the cause of this failure:

1) Was there a loose connection somewhere that I "fixed" while wrestling vigorously with the plastic ATS case to see how the circuit board could be removed.

2) Could there be a faulty capacitor in the circuit board that is causing this problem to only be intermittent.? (My son suggested this based on his experience with an intermittent issue on a radio transmitter)

3) What is the minimum voltage needed for the ATS solenoid to activate? I have read where some folks say they always have the chassis engine running before they start the generator. i.e. 14.2v

The thing is: I have run the PD5100 diagnostics which included pushing the solenoid down with an insulated tool while the generator was running. It would make a connection, but it would not hold that connection by itself (latch) nor would it make the connection automatically.

Maybe UPS will arrive today with the circuit board. I may carry it around with me for a while to see how much of an irritant I still have with this issue. In my old days the maintenance folks would label this issue C-N-D. ( cannot dupicate).

[SQUASHMIRE]

The "bog down intermittently" you describe about the generator to me sounds like the surging behavior a small engine makes when running out of gas. Does that sound like what you are describing? If so, I might add to the list of suspects an intermittent problem with the fuel pump...perhaps related to the pump overheating. Has it been colder outside now that the problem seems to have cleared up? Perhaps colder weather would help keep the fuel and pump cooler and allow generator operation? Just some thots. I am interested in the ultimate solution that I hope you find.

[SQUASHMIRE]

oh, and you asked how a circuit board problem could be intermittent...i have seen this happen when a soldered connection to the board becomes cracked and/or corroded such that vibration, wire position, etc can cause the connect/disconnect difference.

[OldPilot]

Originally Posted by SQUASHMIRE

The "bog down intermittently" you describe about the generator to me sounds like the surging behavior a small engine makes when running out of gas.

It's a propane gen, so I have assumed I won't have the kind of issues one gets with gasoline/diesel.

[booster]

Originally Posted by OldPilot

It's a propane gen, so I have assumed I won't have the kind of issues one gets with gasoline/diesel.

The propane generators have had a bit of a problem also.


I don't have all the details, but it involved a partially/fully plugged air pressure reference line, IIRC. A search on the topic might be in order.


I found this with a quick search. "Make sure vent port is not plugged by mud wasp nest, or it won't work right. Demand reg needs a atmospheric pressure reference (vent port) to determine engine ..."


Looks like lots of hits on Google.

[OldPilot]

I just realized I did not update forum on my new transfer switch circuit board. I as able to put in before Christmas. It was slightly difficult to install. Connections are different and one needs to move the heavy power cables out of the way to change boards. Cables are hard to bend and not much slack.

But the new board works like a champ. Once the generator starts, the board will energize the transfer switch in about 30 seconds.

Now I seem to have trouble getting my generator to start. It's propane gas fueled.

It will start after a few cranks and sounds good for 10 to 15 seconds, then shuts off. It takes a half - dozen or more attempts before it runs constantly.
Once it is on, I can cycle appliances, putting demand on the generator and all seems well. If it was an old gasoline engine, I would think I was turning off the choke too soon. Don't know how that applies to propane.

So, today I let it sit about 3 hours after starting getting it started, then tried again. This time, no problem. Started right up, 25 seconds later the transfer switch put the generator on line. I turned on microwave and A/C Heat strip okay.

What do you folks think? Impending problem? No big deal? It is a little frustrating.