HELP! Onan Generator Problem

Topic: HELP! Onan Generator Problem - SOLVED! (Read 3167 times) previous topic - next topic

HELP! Onan Generator Problem - SOLVED!

August 15, 2011, 02:26:43 pm

I was unable to determine the problem myself, so I took the coach to an Onan-approved service place. Verdict? Bad LP regulator, which was no surprise to me.

Problem? Regulator no longer available from Onan, Rebuild kit no longer available from Onan. Nothing looking like it on Ebay.

Is there something else, a part from a later year generator perhaps. that I can substitute for the bad regulator? I would think if it flows enough and regulates to the right range, anything would be adaptable, but I don't know much about this stuff.

oldMattB

Re: HELP! Onan Generator Problem

Reply #1 – August 15, 2011, 02:39:27 pm

Give a picture of it or a part #

Re: HELP! Onan Generator Problem

Reply #2 – August 15, 2011, 02:41:17 pm

Waiting to hear from shop for a part number - it is about an hour away.

Generator is a 6.5 nhmfa26115c

oldMattB

Re: HELP! Onan Generator Problem

Reply #3 – August 15, 2011, 02:43:21 pm

I can't believe that Onan doesn't know what to replace it with???

Re: HELP! Onan Generator Problem

Reply #4 – August 15, 2011, 02:56:41 pm

from the manual, best I can do right now

Re: HELP! Onan Generator Problem

Reply #5 – August 15, 2011, 03:00:36 pm

A little research comes up with a part # of 305826 for your regulator. 2 versions available from these folk. Seem to know their stuff: Flight Systems 800.403.3728 Plastic one $200.00 metal one $250.00. Confirm everything before you buy as to model # of genny etc.

Keith

Generator Accessories | Generator Exercise Monitor

Re: HELP! Onan Generator Problem

Reply #6 – August 15, 2011, 03:26:46 pm

This was back in 2004, but from my notes: Overhaul propane regulator impco RKJ-2 kit 201017 kit $47.

This was for my: Onan 6.5NHMFA26116C. Serial # B920449612

Brett

Re: HELP! Onan Generator Problem

Reply #7 – August 15, 2011, 03:36:22 pm

@Keith,

I think you are referring to the voltage regulator, part number 305-0826. I am looking for the LP regulator.

@ Brett

I searched for "201017," "RKJ-2," "RKJ-2 kit 20107" and did not seem to find anything that looked like LP regulator parts. Is the Imco you wrote of Imco Trailer, Imco Marine, IMCO Inc. or another?

oldMattB

Re: HELP! Onan Generator Problem

Reply #8 – August 15, 2011, 03:37:41 pm

Maybe Impco?

Re: HELP! Onan Generator Problem

Reply #9 – August 15, 2011, 03:59:49 pm

Onan gave the shop the part number 148-0964.

Re: HELP! Onan Generator Problem

Reply #10 – August 15, 2011, 04:13:53 pm

Yes, sorry, it is Impco. Will change it on post above incase others need the correct name.

Brett

Re: HELP! Onan Generator Problem

Reply #11 – August 15, 2011, 04:48:21 pm

It seems that Brett's number RKJ-2 (sometimes RK-J-2), is an Impco Model J two-stage regulator for forklifts. I do not have my dead one with me, but the Impco sure looks like it. If so, these are commonly available for about $65 new, with the rebuild kit at $28.

How could we verify this? This is much better than the $200 to not available I have read and heard of.

oldMattB

Re: HELP! Onan Generator Problem

Reply #12 – August 15, 2011, 05:22:37 pm

Matt,

OK misread the regulator!

I have spoken with the person below who was most helpful. He said no mystery to all this. It's almost certainly the item Brett posted. Give him a call and he can confirm it and send you the correct kit/part:

Bob 800-221-8467
Moulden Supply Co. Inc. - Home

Keith

Re: HELP! Onan Generator Problem

Reply #13 – August 15, 2011, 05:29:00 pm

Be sure if you overhaul it that you spec the high-temperature/silicone diaphragm.

Brett

Re: HELP! Onan Generator Problem

Reply #14 – August 15, 2011, 05:45:06 pm

Thanks all!

I have provided the info to the shop. I do not know how far from the official Onan recommended part they will go, but they will call Onan and check it out.

I compared the specs and the exploded diagram of the Onan part and the Model J, and they seem identical. Is the high-temperature diaphragm necessary because of the close proximity to the generator block?

If the shop cannot get this far afield, I will call Moulden.

oldMattB

Re: HELP! Onan Generator Problem

Reply #15 – August 30, 2011, 12:45:38 pm

Capstone:

Got the coach back from the shop. Onan told the shop that the LP regulator and the rebuild kit are no longer available. My research indicated that the Onan part is the same as the IMPCO Model J and Model K, which are common forklift regulators. The shop verified this with Onan and the IMPCO supplier, and discovered that IMPCO supplied the regulators for Onan. The shop installed one of these, and the gen is happy! The newest model is the Cobra, which is said to be identical in function. The Cobra is commonly available - I saw one on eBay for under $30, average price about $60.

I estimate that someone could unbolt the generator and pull it onto a skid, leaving the hoses and electrical cord attached, take off the shrouds, replace the regulator and reinstall in about two hours. Having R&R-ed the gen a couple of times, I could probably now do the job in less than one hour.

Hope this helps someone!

oldMattB

Re: HELP! Onan Generator Problem - SOLVED!

Reply #16 – August 30, 2011, 01:06:04 pm

Excellent.

As stated before, you need to verify that the regulator/overhaul kit is made for HIGH TEMPERATURE locations. The difference is a special silicone diaphragm. The "regular"/low temperature regulators would be for installations outside the generator where they are not exposed to the high heat found inside the generator itself.

Brett

Re: HELP! Onan Generator Problem - SOLVED!

Reply #17 – August 30, 2011, 02:33:33 pm

Brett,
The kit you listed earlier, the RJK-2, includes the silicone diaphragm. The Model J-2 regulator is built with the silicone diaphragm, the Model J has a hydrin diaphragm. The Cobra model appears to come standard with a silicone diaphragm.

oldMattB

Re: HELP! Onan Generator Problem - SOLVED!

Reply #18 – August 30, 2011, 02:42:15 pm

Quote from: oldmattb – August 30, 2011, 02:33:33 pm

Brett,
The kit you listed earlier, the RJK-2, includes the silicone diaphragm. The Model J-2 regulator is built with the silicone diaphragm, the Model J has a hydrin diaphragm. The Cobra model appears to come standard with a silicone diaphragm.

oldMattB

Excellent. Will file that in case mine ever goes out.

Brett

Re: HELP! Onan Generator Problem - SOLVED!

Reply #19 – August 28, 2021, 04:45:54 pm

OK, Ive been having the same LP generator issues as was reported in the topic.
When I purchase the coach in May it worked fine. had 1/2 tank or propane and ran fine for about 1500mi. Tanks was below 1/4 so I filled it in Utah (I think). ran until that evening then stopped when a load was applied. Stopped by Onan in ID and they could not find what was wrong. by then it would run for a short time, add a load and it would act like it had no fuel. Been that way since. If no load it will run for maybe 10 mi, if loaded dies in seconds. Oil seems low so I added some-no help! Today I Pulled the Onan 6500 Marquis and got at the Regulator. That is a job getting it out and onto a lift. to get the top cover off. Has on it "IMPCO Model J" and onan part # 148-0964. Here is a pic. I plan on getting another model J and a silicon rebuild kit

Re: HELP! Onan Generator Problem - SOLVED!

Reply #20 – August 28, 2021, 05:56:29 pm

HI,
I have had this problem twice. When you run the propane tank low or empty, the oily scent stuff that gives propane a smell and has collected in the bottom of the tank over the years, will be drawn up and collect in the model j. This will gum up the inside of the regulator. You will need a kit just because you will tear up the gaskets, and diaphragm to clean it. Be sure which way you go, new model j or rebuild your old one, that you keep the RED spring on the gas valve. The new model j will not have this RED spring unless it is made for an onan generator. With out the RED spring in the model j, the generator will be had to start, it will run poorly. My onan genset is a 6.5NHMFA26115c.

Pat,

Re: HELP! Onan Generator Problem - SOLVED!

Reply #21 – August 28, 2021, 06:03:53 pm

Quote from: pthurman48 – August 28, 2021, 05:56:29 pm

HI,
I have had this problem twice. When you run the propane tank low or empty, the oily scent stuff that gives propane a smell and has collected in the bottom of the tank over the years, will be drawn up and collect in the model j. This will gum up the inside of the regulator. You will need a kit just because you will tear up the gaskets, and diaphragm to clean it. Be sure which way you go, new model j or rebuild your old one, that you keep the RED spring on the gas valve. The new model j will not have this RED spring unless it is made for an onan generator. With out the RED spring in the model j, the generator will be had to start, it will run poorly. My onan genset is a 6.5NHMFA26115c.

Pat,

Thanks Pat.
I have the same Genny and coach

I plan on converting it to run on the High pressure vapor side as opposed to the liquid as soon as I fix the regulator. I have heard that on vapor this is never a problem again

I have the manuals for the Onan and some of the drawings and schematics for the coach., but am always looking for more.
If you want to share or set up a drawing file for the '95 U240, let me know,
Joe

Re: HELP! Onan Generator Problem - SOLVED!

Reply #22 – August 28, 2021, 08:44:03 pm

Actually, the gasket set to OH the generator propane regulator has a silicone DIAPHRAGM. They are for high temp applications. Being inside the generator itself, you need the high temp gasket set.

This is NOT a difficult job. Been there, done that AND converted to high pressure VAPOR at the suggestion of an engineer at Marshall Gas. VERY interesting hour at their HQ.

Re: HELP! Onan Generator Problem - SOLVED!

Reply #23 – August 29, 2021, 04:51:06 pm

I think I have confirmed that the Regulator is the problem
Redish brown gunk is ooozing out of the top fittings while sitting horizontal on the desk

Re: HELP! Onan Generator Problem - SOLVED!

Reply #24 – August 29, 2021, 06:38:08 pm

Quote from: Cpt_kludge – August 29, 2021, 04:51:06 pm

Reddish brown gunk is oozing out of the top fittings...

The subject of "oil in the propane lines" has come up here in the past. Link below to some old discussions if you're interested.

Oil Accumulation in Propane System

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