Home » Public Forums » GMCnet » Onan Died
| Onan Died [message #223075] |
Wed, 18 September 2013 22:19  |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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Man, we were just running along with Onan running the roof air. Then it died, about 2 and half hours into our trip. It would restart but die. Have good dash air so I didn't mess with it. An hour later it starts up and runs fine. I was hoping it would not run when we got here so someone could tell me what happened to it.
Dan
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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| Re: Onan Died [message #223079 is a reply to message #223075] |
Wed, 18 September 2013 22:28  |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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| WD0AFQ wrote on Wed, 18 September 2013 20:19 |
Man, we were just running along with Onan running the roof air. Then it died, about 2 and half hours into our trip. It would restart but die. Have good dash air so I didn't mess with it. An hour later it starts up and runs fine. I was hoping it would not run when we got here so someone could tell me what happened to it.
Dan
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Dan,
Mine did that a few years ago. It got progressively worse. I traced it to the fuel pump and replaced the original one with a Mr Gasket, from Jim K. It has worked fine ever since. It would run for a while, then quit. After cooling down, it would repeat this behavior, running for a shorter period each time. Since replacing the fuel pump, it has run constantly for hours without issue.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Onan Died [message #223080 is a reply to message #223075] |
Wed, 18 September 2013 22:31 |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma: 3
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Dan,
You ran the fuel too low in the main tank then stopped to refuel.
Not likely to happen to you- but it has happened to others.
Loose elec connection somewhere?
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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| Re: Onan Died [message #223092 is a reply to message #223075] |
Thu, 19 September 2013 06:03 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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make sure the oil is topped off really good.
Mine looked ok on the dipstick once. I think it was just above the low line. I replaced the LOP switch to the fuel pump. still no go. added some oil to bring it to the top line, and fired up.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: [GMCnet] Onan Died [message #223133 is a reply to message #223075] |
Thu, 19 September 2013 12:13 |
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Personal problem? Operator error?
Just guessing.
At the Loves in Rolla heading to Branson.
Byron Songer
Louisville, KY
ATTENTION: This reply is in reference to what is provided belowŠ
>
>
>Man, we were just running along with Onan running the roof air. Then it
>died, about 2 and half hours into our trip. It would restart but die.
>Have good dash air so I didn't mess with it. An hour later it starts up
>and runs fine. I was hoping it would not run when we got here so someone
>could tell me what happened to it.
>Dan
>--
>Dan & Teri Gregg
>Dexter, Mo.
>
>http://danandteri.blogspot.com/
>
>
>
>
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Byron Songer
Full-timing to enjoy the USA
Former owner but still an admirer
GMC paint schemes at -
http://www.songerconsulting.net
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| Re: Onan Died [message #223168 is a reply to message #223075] |
Thu, 19 September 2013 19:13 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Oily bad connection a LOP switch?? Can't remember if it is N.O. or N.C. to run that theory past my brain. N.O. would mean it would need to have good connection to run.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Onan Died [message #223171 is a reply to message #223168] |
Thu, 19 September 2013 19:24 |
Jim Miller
Messages: 501
Registered: March 2008
Karma: 10
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On Sep 19, 2013, at 8:13 PM, John R. Lebetski wrote:
> Oily bad connection a LOP switch?? Can't remember if it is N.O. or N.C. to run that theory past my brain. N.O. would mean it would need to have good connection to run.
Ken Henderson's 7-Sep-2001 schematic shows that the LOP switch shorts pin 12 to ground in a LOP condition. Therefore removing the wire from the switch (or pin 12 on the board) will allow the engine to run.
--Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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| Re: Onan Died [message #223218 is a reply to message #223075] |
Fri, 20 September 2013 09:05 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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So N.C, pressure opens switch. Board delay runs it till pressure established at startup? Then if still closed or becomes closed it shuts down.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Onan Died [message #223221 is a reply to message #223218] |
Fri, 20 September 2013 09:24 |
Jim Miller
Messages: 501
Registered: March 2008
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On Sep 20, 2013, at 10:05 AM, John R. Lebetski wrote:
> So N.C, pressure opens switch. Board delay runs it till pressure established at startup? Then if still closed or becomes closed it shuts down.
The problem with this design is that it is fail-deadly (or it can experience a "wrong-side failure" in British railway-speak). If the LOP wire vibrates loose or otherwise becomes disconnected then the machine will happily stay running even in a low- or no-oil pressure condition.
If it were designed fail-safe then a disconnected wire would cause the control board to think there was an LOP fault and shut the machine down.
--Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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| Re: [GMCnet] Onan Died [message #223229 is a reply to message #223218] |
Fri, 20 September 2013 12:04 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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The pressure switch is bypassed while the starter is operating. And there's a bit of delay in the circuit which the pressure switch grounds on low pressure. I suspect that if one were to swap the switch with the one Junkerac recommends changing to on my setup (swapping a 10-14 PSI operate for a 5 PSI operate) the Onan would be somewhat happier when things get hot. Simpkly removing the wire from the switch will stop it from killing the engine - but you will lose the safety of a low pressure shitdown.
--johnny
--------------------------------------------
On Fri, 9/20/13, John R. Lebetski <gransport@aol.com> wrote:
Subject: Re: [GMCnet] Onan Died
To: gmclist@temp.gmcnet.org
Date: Friday, September 20, 2013, 2:05 PM
So N.C, pressure opens switch. Board delay runs it till
pressure established at startup? Then if still closed or
becomes closed it shuts down.
--
John Lebetski
Chicago, IL
77 Eleganza II
Source America First
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Onan Died [message #223230 is a reply to message #223075] |
Fri, 20 September 2013 12:14 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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| WD0AFQ wrote on Wed, 18 September 2013 20:19 |
Man, we were just running along with Onan running the roof air. Then it died, about 2 and half hours into our trip. It would restart but die. Have good dash air so I didn't mess with it. An hour later it starts up and runs fine. I was hoping it would not run when we got here so someone could tell me what happened to it.
Dan
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A problem with the LOP switch or even low oil level, would not produce the symptoms that Dan's Onan is showing. Look at the statement above where he says "An hour later it starts up and runs fine". If it were a bad LOP switch or low oil level, it would not run fine, again, after cooling down.
At the beginning of last year, my Onan was doing that exact thing. I finally replaced the fuel pump - end of problem.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
[Updated on: Fri, 20 September 2013 12:15] Report message to a moderator |
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| Re: Onan Died [message #223231 is a reply to message #223230] |
Fri, 20 September 2013 14:53 |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma: 3
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Carl,
What a novel concept!! You mean, you actually READ and maybe understand the problem before diagnosing and offering solutions?
Is that A new procedure on the GMC net?
Tongue not entirely embedded in cheek.
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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| Re: Onan Died [message #223234 is a reply to message #223231] |
Fri, 20 September 2013 15:50 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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Gene,
Maybe we can start a trend. 
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Onan Died [message #223292 is a reply to message #223234] |
Sat, 21 September 2013 09:34 |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma: 3
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Senior Member |
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Carl,
Don't do that. It may diminish the entertainment value of the net!
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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| Re: Onan Died [message #223313 is a reply to message #223075] |
Sat, 21 September 2013 17:35 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Maybe he has LOP when hot?? And the switch is doing its job.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Onan Died [message #223315 is a reply to message #223313] |
Sat, 21 September 2013 18:38 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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| JohnL455 wrote on Sat, 21 September 2013 15:35 |
Maybe he has LOP when hot?? And the switch is doing its job.
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Maybe. But I don't think it takes all that long for an Onan to warm up to operating temperature. I thought mine was doing that as well, since I had just changed to Parts Plus 30w oil. I added a bottle of STP. it didn't change the behavior. When I replaced the fuel pump, which would pump fine when cold, it fixed the problem. Our last trip, we ran the Onan and roof air for a steady three hours plus, (in July, in Arizona, through Phoenix, and on to Tucson) without issue, even through a gas stop in Eloy. It never even coughed.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Onan Died [message #223317 is a reply to message #223315] |
Sat, 21 September 2013 18:52 |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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| Carl S. wrote on Sat, 21 September 2013 18:38 |
Maybe. But I don't think it takes all that long for an Onan to warm up to operating temperature. I thought mine was doing that as well, since I had just changed to Parts Plus 30w oil. I added a bottle of STP. it didn't change the behavior. When I replaced the fuel pump, which would pump fine when cold, it fixed the problem. Our last trip, we ran the Onan and roof air for a steady three hours plus, (in July, in Arizona, through Phoenix, and on to Tucson) without issue, even through a gas stop in Eloy. It never even coughed.
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If not already done, you need to get that STP out of your Onan. That stuff will seize a small engine, normally within seconds. You may have dodged that bullet, but don't press your luck. Change the oil immediately.
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