4th Onan Cummins 2500 LP Generator Help Post. ????

[HadEnough]

Ok. Next problem.

The latest problem with my 2500 LP generator is it fails to turn on the juice.

I have it running like a top overall. It starts right up and runs smoothly. Has been wonderful with frequent air filter changes. Until...

It stopped producing power.

It doesn't turn on the electricity after that little startup delay. No power coming out of it.

What's the first few easy things to check?

[bounder39zman]

I use a simple bbq grill propane tank, with an adapter fitting to connect to the generator inlet. you need a primary regulator, like most RV propane tanks use. make sure to stand it up with valve on top. as you want vapor only.
The 2.5 KV Onan LP set was used for about 20 yrs, then replaced a few years ago by the HGJBB model. They have completely different control systems, and knowing which you have would be helpful in diagnosing problem.
And, I agree....I hate to see these come to shop, as usually are mounted under vehicle, behind rear axle, and you cant do anything except basic service...and that is difficult. I have never had a customer that said they ever would crawl under the vehicle to even check oil

[MEXICOWANDERER]

HadEnough wrote:
Anyone? Anyone work on their own Onan LP?

Every ONAN I have EVER owned was LPG because of limited run-time and lazy maintenance features.

Stop guessing




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These are LED 120 volt PILOT LIGHTS. Everywhere there is a switch, a relay or breaker I have a pilot light. When things are running the pilot lamps glow, when a pilot lamp is not glowing and it should I go right to the spot.

Double pilot lamps entering an RV one on each leg on the power pedestal inlet one on the generator inlet and one on each of the split circuits coming out of the rig circuit breaker box.

Sue me, I'm lazy. I haven't got the energy to chase down problems. Either the freakin' pilot light is glowing or it isn't.

The pilot lamps on the BORG have been glowing 24/7 seven years because they are LED.

I even have pilot lamps on the stick & brick service entry drop sixty yards distant up on the hill.

I wire in LED pilots across all circuit breakers.

Because I am lazy. Good technicians are lazy. If I spend more than 10 seconds troubleshooting one of my circuits I start to steam.

You are not a tech so you need to focus on having a professional level of troubleshooter's ability with a novice's education and experience.

With LED pilot lamps an hour or two borrowing or begging a handyman's ability you too can become a pinpoint accuracy troubleshooter for your AC and your DC power system

[HadEnough]

bounder39zman wrote:
please........ post your model and spec #. Those who may hsve info to help you may be better able to help you. If the Genny continues to run after start up, then it is making a.c. power. The control board will shut it off after start-up if not making power. Problem is likely at connection box or at c/b connections, as O.P. have suggested.

Ok. I'll get that model number ASAP.

It's an Onan Microlite 2500 lp

There is a hot, neutral and ground that comes out of the side of the generator itself. These are connected to something inside the generator and connected to the connection box on the RV.

I disconnected the generator from the RV at the connection box to see what was going on. No power out of the generator. The hot, neutral and ground coming out of the side of the generator have no voltage on them relative to each other.

Which is why I was asking how people run these propane generators on the bench. Next step is I have to remove the generator to be able to get inside it. It's inaccessible the way it's installed in the RV.

When I remove it, it has no propane source. How do people usually supply the propane to run them on the bench?

[bounder39zman]

please........ post your model and spec #. Those who may hsve info to help you may be better able to help you. If the Genny continues to run after start up, then it is making a.c. power. The control board will shut it off after start-up if not making power. Problem is likely at connection box or at c/b connections, as O.P. have suggested.

[HadEnough]

marcsbigfoot20b27 wrote:
On mine as soon as the engine starts you have AC power immediately.

There must be something between the gen and where you are measuring output.....is there a hardwired EMS or transfer switch?

I'm measuring voltage on the hot, neutral and ground that are inside the generator itself. The ones wired to the RV electrical system.

No voltage produced anymore.

I worked my way back there from the transfer switch which was where I started testing.

The generator doesn't produce AC power.

[marcsbigfoot20b]

On mine as soon as the engine starts you have AC power immediately.

There must be something between the gen and where you are measuring output.....is there a hardwired EMS or transfer switch?

[HadEnough]

marcsbigfoot20b27 wrote:

HadEnough wrote:
Anyone? Anyone work on their own Onan LP?

Yes, I have/do.

Get the service manual PDF.
I have diagnosed (painfully) a faulty regulator that would cause gen to suddenly shut off randomly, set up volts and hertz and cured surge, rebuilt the LP demand regulator with a kit.
Learning experience for sure. Not that scary for me as I used to be an ASE master tech, but still frustrating at times.

What is the issue now?

Thanks. The issue is the generator stopped putting out AC voltage.

You know how you start it, wait for it to come up to speed, warm up a few moments and do some self checks... Then you hear a click and AC voltage is turned on for production out of the unit?

That never happens on mine. It runs like a champ since I've been taking great care of it, but it just won't turn on the AC power. No power at all is produced when the generator is running.

Been searching for the Service Manual PDF online and am coming up short for this model.

[marcsbigfoot20b]

HadEnough wrote:
Anyone? Anyone work on their own Onan LP?

Yes, I have/do.

Get the service manual PDF.
I have diagnosed (painfully) a faulty regulator that would cause gen to suddenly shut off randomly, set up volts and hertz and cured surge, rebuilt the LP demand regulator with a kit.
Learning experience for sure. Not that scary for me as I used to be an ASE master tech, but still frustrating at times.

What is the issue now?

[MEXICOWANDERER]

A Poster Boy subject for the

SMOKE STACK

forum?

[HadEnough]

Anyone? Anyone work on their own Onan LP?

[HadEnough]

Reviving this thread because I finally had time to check everything out.

I checked the hot and neutral coming out of the generator itself. DEAD.

The generator isn't switching on the AC power.

I have 2 questions now.

1) How do you guys normally supply propane to a propane generator to bench test it?

2) What control, specifically, turns the AC power on when the generator is up and running, warm and decides it's time to start supplying AC? I see a couple solenoids through the vent that are very close to the Hot, Neutral and Ground wires. I'm wondering if one of those solenoids closes the circuit to output AC and might be bad. Seems like the most likely thing to me but I'm not sure what they do.

[HadEnough]

Ok these are some great troubleshooting clues! Thanks!
I'll check those spare connectors and it's excellent to know the generator shuts down if it doesn't sense output from the powerhead.

Really, this points to a loose connection which makes a lot of sense given the miles I've put on this RV and hours on the generator.

[marcsbigfoot20b]

So the generator continues to run?
If so then at least the unit is making/sensing power output.
If no output from the gen itself, it wont stay running without holding the start button down.
I have a 2500LP also.

[STBRetired]

There are spade connectors connecting the generator output to the back side of the breaker on the generator. Have seen those vibrate off of the breaker on 2 Onan 4000 Microlites. Worth a look, only a couple of screws to remove.