Generator

Topic: Generator (Read 1198 times) previous topic - next topic

Generator

July 25, 2011, 12:00:16 am

Just back from trip to Gatlinburg. Everything went well except for more Onan propane generator problems which I thought were behind me after the new ignition coil seemed to cure the ATS from tripping under heavy load. I've been noticing oil consumption but no leak or smoking but I've been checking and adding as needed. The unit ran fine all the way up but on the way back I thought my old problem of the ATS tripping under load had returned. In fact it may have but I don't hear the typical ATS sound as before or any change in sound to the motor like it is struggling. Instead the AC power just goes off. After several episodes of this I stopped for fuel and even though the AUDIT showed 1/2 tank of propane and the gauge on the tank showed 1/4 and these units are supposed to run till nearly empty, I filled the tank and topped off the oil. No more power drop out the rest of the way home. As I said, the motor never stopped or struggled. If it was the oil level switch, the motor would shut down. So it must be something related to the propane tank being full vs. 1/4 full. Would a failing regulator cause the power to cease without the motor shutting down or acting starved for fuel? This makes no sense but filling the tank did the trick. The power was totally unreliable until I filled it up.

Re: Generator

Reply #1 – July 25, 2011, 12:47:41 am

You might need a new regulator. And when was the last time you changed the fuel filter?

But I will defer to Dave M and Brett Wolfe on this matter. They both know lots more about these generators than I do. But at least I gave you something to look at until we hear from them.

Re: Generator

Reply #2 – July 25, 2011, 08:36:27 am

Yes, if you have done a tune-up and still have erratic generator operation, the regulator which is located on the generator on your liquid LP generator is suspect. It is a fairly common regulator, but because of its orientation in the generator, is subject to clogging from the long hydrocarbon chain impurities in propane. When overhauled or replaced, it is quite likely that you will see a quantity of a light viscosity grease-like substance in the regulator.

That comes from the liquid LP. That is why many of us have converted to high pressure (T in before house regulator) VAPOR. No negative aspects unless you plan on generator operation in well below freezing temperatures. Then low vapor pressure could be an issue.

Brett

Re: Generator

Reply #3 – July 25, 2011, 08:41:37 am

Dwayne, I think you have done all the guessing on your generator and for the present issue you mention, I feel it is time to do some trouble shooting. For the fuel issue you will need a way of measuring the water column in inches, this is one measurement required for proper diagnostics of a gaseous fuel item.
I use a meter or you can use the actual water column method. That is way too sloppy for me.
But until you know where you are with the fuel setup, you are guessing at best, Guessing is not real good nor accurate.
Seems I emailed you the service manual for your NHM Onan. Now would be a great time to read the LP Gas section.
If I have not emailed it, it is available on this forum.
Good luck

Re: Generator

Reply #4 – July 25, 2011, 07:51:06 pm

I was able to duplicate the problem today. Since the ignition repair it has been a bear to start when before it fired right up. It will run for a while as before until the AC comes up but now when that happens, it doesn't want to take any load. Today it actually did shut down not just cease making power. It is acting like it needs an extended warm up period compared to before. I am going to check the air filter as the collapsing insulation may have polluted it severely. I've read the manual but my technical skills stop at changing the oil. My generator is hooked up to the vapor side already but that doesn't mean the regulator isn't failing. After several restarts, it seems to straighten out and function normally. What should be the normal oil consumption on this unit? It sat unused for so many years, the seals are probably all dried out. Then again I'm seeing no leakage or smoking. Since I have to pull the unit to redo the insulation, it might be time to just have it rebuilt.

Re: Generator

Reply #5 – July 25, 2011, 08:07:18 pm

At least check valve clearance and adjust if needed, new good spark plugs, as far as oil useage, that is hard to tell, I wuld use a #30 HD oil, not a multi vis such as 10W-30, if you stick to 30HD, you will be happier.
would not go for a "overhaul" just check valves, and make sure the gaskets are good, such as head gasket, intake gaskets, gasket on carb mount.

If these things are too difficult, find a Onan shop and have it done. I see no point in keep playing with what does not work right. The more you mess with a non working unit, it just makes things more expensive as people tend to keep turning things that get more costly to FIX later on.

Again, the gas pressure in the LP system is a major issue, if you do not have the equipment nor the experience for this, then find a shop that understands what they are doing. When it is correct, everything is happy, otherwise it is just a trouble spot.
Cheers

Re: Generator

Reply #6 – July 25, 2011, 09:00:18 pm

Think Dave's on the right track with this one. If you don't want to try to DIY, call around to a Onan dealer and take your rig in WITH the manual he sent you. If nobody in your area, do an online search for closest or call your propane dealer for a referral.

Doubt very much if your generator needs rebuilding. They can sit for quite a while and while the seals may not be spring chickens, they will probably be OK. Even when seals do leak, additives in a can do wonders. So, change the air cleaner and be ready for a simple cure like the regulator. Change oil and watch the level for the first several hours after it's running correctly.

I smelled propane on our U300. With soap and water, I could see there were occasional bubbles at the regulator next to the tank. Went to Sacramento to a discount trailer supply co. and for $19.95 I had a new 2 stage regulator better that the OEM, so your parts should not be too bad depending on the dealer.

Re: Generator

Reply #7 – July 26, 2011, 10:59:39 am

http://www.flightsystems.com/pdf/onanrvtshootgd608.pdf

"RV Generator Troubleshooting Guide"

oldMattB

Re: Generator

Reply #8 – July 26, 2011, 02:29:21 pm

Since the regulator is a rather inexpensive item, perhaps changing it out prior to spending even more money at Onan?Cummins might be a good investment. Would someone who has changed one out please reply with instructions and remember I'm not the most mechanically inclined so tell me where to find it, what it looks like and the steps to change it. Thanks

Re: Generator

Reply #9 – July 26, 2011, 02:34:16 pm

Dwayne,

Been too long to remember the step by step, but as I recall, does require the removal of the generator from the coach.

Brett

Re: Generator

Reply #10 – July 26, 2011, 05:55:57 pm

What regulator is used? Must it be Onan stuff? Would a generic fit without re-routing the pressure lines?

I have my gen out right now - I can't imagine R&R of the regulator with the gen in the coach. Removal took me about ten minutes: Pull slide out, undo four bolts, slide generator onto motorcycle jack and pull out to limits of fuel and electrical lines.

oldMattB

Re: Generator

Reply #11 – July 26, 2011, 08:15:33 pm

Revision of opinion:

I put new insulation in the bay, and reinstalled the sliders, and discovered that the sliders are dual extension. After a big dose of WD40, I was able to get them to work - they were filled with grit and would not budge beyond the first extension.

I think r&r of the regulator without removal of the gen would be difficult but possible. One would likely have to work through the opening under the bay to get access for removal of the back plate. The pressure pipes would be accessible from the top panel, but probably not the regulator mounting bolts.

While I have the gen out, would still like to know if the regulator is a generic part. Mine won't start, and I have checked most of the rest. I have ordered a new controller board - it may be the cause of my problem, and the generator has tried to start on its own a couple of times.

oldMattB

Re: Generator

Reply #12 – July 26, 2011, 09:07:39 pm

I was hoping the item right in front right of first picture was it. Also, can anyone tell me if the blue item on the front of the propane tank in the second photo is a hook-up for a gas grill?

Re: Generator

Reply #13 – July 26, 2011, 09:49:20 pm

Yeah, that looks like it. On my gen, the regulator is inside the generator case, in the left rear corner. I don't know enough to speculate about the difference.

You probably do have a grill hookup - we do.

oldMattB

Re: Generator

Reply #14 – July 26, 2011, 10:34:21 pm

Agree with Matt, OE regulator was internal to the generator, at least our 1993 U240 was fit with a liquid LP generator with internal regulator.

Brett

Re: Generator

Reply #15 – July 27, 2011, 06:49:03 am

In Dwaynes picture, it is showing along with the control panel, the vapor regulator, the 148-0311 regulator, sure not a liquid setup.
It sure helps once you know what the setup is.
This is such a screwed up non standard application, it is funny.
I would be interested in closely checking out the tank setup with regulator(s).
Again, a pressure gauge to check for the 11" WC input to the 148-0311 regulator is EXTREMELY important.
I see deaf ears here.
Cheers

Re: Generator

Reply #16 – July 27, 2011, 07:07:35 am

Dave,

I read and understand your comments. I don't have the knowledge or equipment to check the pressure. If the regulator is a $40 bolt-in replacement part, I will replace it while I have the generator out. Otherwise, I will take the coach to a shop, pay my $1/2G for proper repairs, and go work on something else. I have spent about a day working on the gen, and that is about enough for me. I still do not know what the problem is, and I have exhausted my capabilities and my back.

At this point, the gen sometimes starts, sometimes stops when the button is released, once failed to stop when the button was pressed, shows no more than 6 volts at the coil primary, never turns fast-enough to remain running, back plug will not fire even when the plug and wire are exchanged (verified by a skeptical friend), and has tried to start several times without the button being pushed.

oldMattB

Re: Generator

Reply #17 – July 27, 2011, 09:41:58 am

Dave, Who would you suggest I have look at this...Onan or a propane dealer? All of my propane appliances work fine and even the generator is working so long as I let it really, really warm up (as compared to how it worked before). I cannot load it with even one A/C unit immediately after the delay expires to provide 110 to the coach. I doesn't hunt or surge and sounds good. The electricity just cuts off with the engine still running or sometimes the engine just stops. After warming up it seems to be ok. I do think it uses propane more excessively than it should. Onan never said anything about a screwy set-up the various times I had it there trying to get to the bottom of the ATS kicking open every time I loaded it up prior to the ignition coil going kaput. The new coil stopped that and it worked great for a few months.

Re: Generator

Reply #18 – July 27, 2011, 11:22:02 am

It appears you have a fuel issue, so you need a generator person who knows and understands LP Gas, the gas company usually are clueless as to how generators operate or what they need to operate correctly. We have to educate the LP Gas suppliers frequently on this issue.
The key word it being able to check and understand the pressure readings required to properly operate the generator, Getting everyones guess is great, but sooner or later you most likely would like to have it fixed.

The issue with the pressure gauge is simply to have 11-13"WC and never drop below 5"WC at the worst condition, meaning during start, air conditioner start or at any time.

NEVER have ZERO pressure even for a millisecond. If you do, you have a problem.
Without the ability to check this pressure, you are GUESSING, guessing aint gonna solve nuttin. Get the gauge/meter or have someone with it to do the checking.

Re: Generator

Reply #19 – July 27, 2011, 03:36:46 pm

Thanks. Back to Cummins/Onan soon I guess. Should one of these type units need more warm-up than the delay to run one A/C unit or should they be ready to go once the 110 kicks in?

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