Onan generator only runs with switch held in

[loving_retireme]

Last month my Onan 2800 ran perfectly, today I can't get it to run at all. Here are the details:
(1) Pushing in on the remote start/stop button inside the Roadtrek and also at the access cover at the generator get the same results.
(2) I checked the oil and it is with the recommended level.
(3) Pushing in either switch results in the starter starting the generator gas engine, however the generator stops the moment I release the switch.
(4) Pushing in on either switch and continuing to hold it in result with the generator gas engine to continue to run, but only as long as I hold the switch in.
(5) While holding the start switch in the run position 120VAC never arrives at any electrical outlet.

I am open to any suggestions/ideas of what my Onan problem is.

[Jim_Carolyn]

I talked to Onan last week and they gave me a name and phone number of a customer service person to call so I passed that info along to my repair guy. Today I talked to the owner of the repair shop and he told me he called and talked to the customer service person from Onan and he feels confident he will finally be able to get the voltage regular next week that he's had on order for over 2 months. We'll see and if it does arrive, we'll see if that was really the problem.

[psa0298]

I just had my 1990 onan marquis 6500 in to the cummins/onan shop last week for the very same problem. They advised it was the rotor slip rings. Over time the rings get a residue on them and they need to be cleaned and polished. It can keep the brushes from making proper contact and therefore will not produce AC power. The generator is designed so that it will not run unless it produces AC power. It could be the voltage regulator as well...they tested it first.

[Jim_Carolyn]

Yeh, I'm not sure what his problem is but I've waited long enough and I'm ready to go pick it up.

[Handbasket]

Jim, If he did that diagnosis without doing any testing, he may have found out he was wrong. Obtaining & replacing the voltage regulator should take about a week, tops.

When my brand-new 2800 failed in the same way, I took it to a nearby RV dealer who claimed to handle Onan warranty repairs. I have almost no doubt that he expected it to be the VR. Went back a few weeks later, it was sitting on bench, top off, not fixed. He finally claimed that 'didn't have a tech who had time to work on it'. Took it to the Onan dealer 80 miles away, proper diagnosis revealed it was a bad stator & rotor. Cost Onan $1600.

It can also be brushes / commutator, from what I think I know.

Jim, "I used to be schizophrenic, but we're OK now."

[Jim_Carolyn]

What exactly do you mean by "older" or "newer" model? I don't see mine as a "newer" model.

[powderman426]

Jim&Carolyn wrote:
I had/have the same exact issue on my Onan 2800 generator. I removed it and took it to the garage to a mechanic that says he repairs Onan generators and he says it needs a new voltage regulator and "ordered" one. That was 3 months ago and I still waiting for it to get fixed.

Yes the voltage regulator would be what's on the newer models. The older units used the resister.

[Jim_Carolyn]

I had/have the same exact issue on my Onan 2800 generator. I removed it and took it to the garage to a mechanic that says he repairs Onan generators and he says it needs a new voltage regulator and "ordered" one. That was 3 months ago and I still waiting for it to get fixed.

[Arizona_Kid]

This use to come up in the old days of the forum, 2002 to maybe 2008, since then I haven't see much of the problem. Maybe powderman has it right.

[loving_retireme]

ROADTREKKER2000 wrote:
The amount of gas in the RV gas tank is criticle to operating the Onan generator.

When your RV gas tank gets below a quarter of a tank, the Onan will not run. This is a design feature to prevent the generator from using up all your RV gas.

'1775' made this point, but your response implies you didn't understand his comment.

My tank is 1/2 full and I stated that the generator gas engine will continue to run as long as I hold the switch on - for a minute or more if I just hold the switch on.

[ROADTREKKER2000]

The amount of gas in the RV gas tank is criticle to operating the Onan generator.

When your RV gas tank gets below a quarter of a tank, the Onan will not run. This is a design feature to prevent the generator from using up all your RV gas.

'1775' made this point, but your response implies you didn't understand his comment.

[powderman426]

Some of the older units had a wire wound resister in the start circuit. The idea was that when pushing the start button it gave full voltage to the circuit to make starting easier. When the button is released the resister would cut the voltage back somewhat to reduce wear. If the resister burns out the circuit goes open when the button is released. If you have the resister you can check it with an ohm meter. If it had electronic ignition, you need to look elsewhere.

[ksg5000]

Here's a thread that might help.

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/26439123/print/true.cfm

[Roman_Duck]

Handbasket wrote:
You've got a failure to produce AC voltage. It's possibly the voltage regulator, the brushes, or the rotor-stator assembly.

The regulator is in the $250 range for parts (google 'Flight Systems'). It's a doable but dang fiddly DIY repair. There's a hidden Torx screw that's an utter bear to restart, with no lead-in to the hole and no tabs to locate the regulator.

IIRC, the Onan service manual takes you thru troubleshooting steps to isolate what the problem is. You'll need a volt-ohm meter & basic skills.

Jim, "Unapologetic flatulator."

Bad voltage regulator, contact flight systems, they will test your old one and confirm the good or bad.
Had same problem, sent it in. Had it tested, found to be bad. order new one. Started right up and stayed running without finger holding.
They do charge for testing, but if it's bad they will waive the test fee and apply the cost towards a new one

[loving_retireme]

1775 wrote:
Try starting the generator with the van engine running. Leave it running for a few minutes after the generator starts and stays running. I have found that if the Roadtrek batteries are low the generator will either not start at all or is hard starting. Make sure that there is nothing turned on inside the Roadtrek to take off all power loads when trying to start the generator and it is hard starting. Make sure the A/C switch is off, unplug the microwave. While this is not so much of a problem when all is well, when the generator is not starting this can be one of the problems. Also do you have more than a 1/4 tank of gas in the van? The generator will not start or run with less than a 1/4 tank.

Once you do get it started you may find that if you turn on a power load soon after starting it will stop again. Let it run for awhile before adding a power load - when it is hard to start.

I do not believe the engine battery is a problem since the generator gas engine is not hard to start and run smoothly as long as I hold the switch in. Also no 120VAC devices are turned on, but that does not matter since no AC is being delivered at the automatic transfer switch. As far as the l/4 tank, I don't believe that the generator gas engine would even turn over if I was low on gas. If I am incorrect on any of these points please correct me.

[Handbasket]

You've got a failure to produce AC voltage. It's possibly the voltage regulator, the brushes, or the rotor-stator assembly.

The regulator is in the $250 range for parts (google 'Flight Systems'). It's a doable but dang fiddly DIY repair. There's a hidden Torx screw that's an utter bear to restart, with no lead-in to the hole and no tabs to locate the regulator.

IIRC, the Onan service manual takes you thru troubleshooting steps to isolate what the problem is. You'll need a volt-ohm meter & basic skills.

Jim, "Unapologetic flatulator."