Home » Public Forums » GMCnet » Onan (Is this a board problem?)
| Onan [message #150814] |
Sun, 27 November 2011 21:07  |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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While dry camping at the dunes this weekend, my usually trustworthy Onan started acting up. I had it running to bring the batteries up to charge and charge netbooks, cell phones, etc, plus heat some water, and microwave some of the dinner. Right after the water heater turned it's self off, the Onan started to cough, surge, and backfire. I shut it off and turned to the internet for help.
I found Duane's info on Gene's site, and read in the trouble shooting info to jumper terminal 9 to terminal 5. This was after I checked the fuel pump, and disassembled the carb, cleaned it, and reassembled it. As soon as I connected the jumper wire, the fuel pump started running and when I hit the start switch, it fired up and ran as well as it ever has. I had to do the same thing tonight when I went to fire it up.
Does this sound like a bad control board, or could it be a problem with the low oil circuit?
Thanks guys.
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: [GMCnet] Onan [message #150816 is a reply to message #150814] |
Sun, 27 November 2011 21:20  |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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On Nov 27, 2011, at 8:07 PM, Carl Stouffer wrote:
>
>
> While dry camping at the dunes this weekend, my usually trustworthy Onan started acting up. I had it running to bring the batteries up to charge and charge netbooks, cell phones, etc, plus heat some water, and microwave some of the dinner. Right after the water heater turned it's self off, the Onan started to cough, surge, and backfire. I shut it off and turned to the internet for help.
>
> I found Duane's info on Gene's site, and read in the trouble shooting info to jumper terminal 9 to terminal 5. This was after I checked the fuel pump, and disassembled the carb, cleaned it, and reassembled it. As soon as I connected the jumper wire, the fuel pump started running and when I hit the start switch, it fired up and ran as well as it ever has. I had to do the same thing tonight when I went to fire it up.
>
> Does this sound like a bad control board, or could it be a problem with the low oil circuit?
>
It could be either. Why don't you check out the switch first? The low oil pressure switch goes to terminal 12 on the board. When the oil pressure is low the switch closes and grounds terminal 12. So, if you disconnect the wire and find that everything works well then you know its the low oil pressure switch.
If that doesn't do anything then it is probably a bad control board.
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: [GMCnet] Onan [message #150818 is a reply to message #150814] |
Sun, 27 November 2011 21:27 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Carl,
The oil pressure sensor can go bad and shut off the fuel.
Get a VW oil pressure sensor #201-1078 Beckarney
Should you want to use a test board if you have continued problem, let us know.
On Sun, Nov 27, 2011 at 7:07 PM, Carl Stouffer <carljr3b@yahoo.com> wrote:
>
>
> While dry camping at the dunes this weekend, my usually trustworthy Onan started acting up. Â I had it running to bring the batteries up to charge and charge netbooks, cell phones, etc, plus heat some water, and microwave some of the dinner. Â Right after the water heater turned it's self off, the Onan started to cough, surge, and backfire. Â I shut it off and turned to the internet for help.
>
> I found Duane's info on Gene's site, and read in the trouble shooting  info to jumper terminal 9 to terminal 5.  This was after I checked the fuel pump, and disassembled the carb, cleaned it, and reassembled it.  As soon as I connected the jumper wire, the fuel pump started running and when I hit the start switch, it fired up and ran as well as it ever has.  I had to do the same thing tonight when I went to fire it up.
>
> Does this sound like a bad control board, or could it be a problem with the low oil circuit?
>
> Thanks guys.
> --
> Carl S.
> '75 ex Palm Beach
> Tucson, AZ.
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Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
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www.appliedgmc.com
1-800-752-7502
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| Re: Onan [message #150821 is a reply to message #150814] |
Sun, 27 November 2011 21:39 |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma: 3
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Carl.
I had the identical problem several years ago. Onan ran fine with the jumper would not run without.
On Miguel's advice I ordered and installed a Dinosaur replacement board. No problem with the gen set since.
Thanks for the pictures on the Chrysler seats.
I have concluded that my seats are mid row seats and yours and Al Scott's are front row seats.
I will have to cut off some extra metal brackets but after seeing your pictures I'm sure that I can make mine work and also look good.
I assume that the 3:70 limited slip kept you out of trouble in the sand pit this week end.
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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| Re: Onan [message #150830 is a reply to message #150814] |
Mon, 28 November 2011 07:15 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| Carl S. wrote on Sun, 27 November 2011 21:07 |
While dry camping at the dunes this weekend, my usually trustworthy Onan started acting up. I had it running to bring the batteries up to charge and charge netbooks, cell phones, etc, plus heat some water, and microwave some of the dinner. Right after the water heater turned it's self off, the Onan started to cough, surge, and backfire. I shut it off and turned to the internet for help.
I found Duane's info on Gene's site, and read in the trouble shooting info to jumper terminal 9 to terminal 5. This was after I checked the fuel pump, and disassembled the carb, cleaned it, and reassembled it. As soon as I connected the jumper wire, the fuel pump started running and when I hit the start switch, it fired up and ran as well as it ever has. I had to do the same thing tonight when I went to fire it up.
Does this sound like a bad control board, or could it be a problem with the low oil circuit?
Thanks guys.
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Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Onan [message #150833 is a reply to message #150830] |
Mon, 28 November 2011 07:43 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| Ken Burton wrote on Mon, 28 November 2011 07:15 |
| Carl S. wrote on Sun, 27 November 2011 21:07 |
While dry camping at the dunes this weekend, my usually trustworthy Onan started acting up. I had it running to bring the batteries up to charge and charge netbooks, cell phones, etc, plus heat some water, and microwave some of the dinner. Right after the water heater turned it's self off, the Onan started to cough, surge, and backfire. I shut it off and turned to the internet for help.
I found Duane's info on Gene's site, and read in the trouble shooting info to jumper terminal 9 to terminal 5. This was after I checked the fuel pump, and disassembled the carb, cleaned it, and reassembled it. As soon as I connected the jumper wire, the fuel pump started running and when I hit the start switch, it fired up and ran as well as it ever has. I had to do the same thing tonight when I went to fire it up.
Does this sound like a bad control board, or could it be a problem with the low oil circuit?
Thanks guys.
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I'm having a problem understanding exactly what is happening here.
On your first paragraph symptoms my comment is:
After starting the board does only one thing. It supplies +12 volts to the fuel pump and the ignition. Generally you have +12 at these places there or you do not. If this indeed is an electrical problem to the pump and ignition, what you are describing sounds like an intermittent connection rather than a board failure.
In your second paragraph you state that the jumper is now required to make it run at all. This now sounds like an electrical problem and could be the board, the low pressure switch, or the alternator / charger in the Onan that tells the board that your Onan is running.
I'm with Emery on the LOP switch. If unplugging it does not change anything, then read the AC voltage coming out of the alternator. Meter between pins 5 and 8 with it running. It should be in the 28 to 32 VAC range. If that is OK, there are many other electrical things that could cause this, but the board is probably the next on the list.
I hate to ask this, but did you replace the 5 amp fuse on the board?
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Onan [message #150838 is a reply to message #150833] |
Mon, 28 November 2011 08:31 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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Ken,
I did not replace the 5 amp fuse. The generator WILL fire up without the jumper in place. It just surges, and acts like it is running out of gas. It was almost a quart low on oil but filling it did not make any difference. It will rum smoothly with the jumper from 9 to 5. I will try Emery's suggestion when I get home. Leaving this morning.
Thanks to all who replied here or emailed me. This is a great group. Without the info provided here and other GMC sites, I would have had to get out the little construction generator I keep in the work truck.
Here are a couple of pics:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=41605
http://www.gmcmhphotos.com/photos/showphoto.php?photo=41602
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 [message #150840 is a reply to message #150838] |
Mon, 28 November 2011 09:14 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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Carl, soldered On the board is 2 retangular relays. one of these is a fuel pump power only when the gen is running. If this relay is weak or has dirty points it could cause your fuel pump to sputter when removing the 9-5 jumper. You can carefully pop the covers and visually check the relay in action. I have had limited luck trying to clean or adjust. There are rumors that a steady hand with a soldering iron can replace these relays.
would the manuals help?
http://bdub.net/manuals/index.html
| Carl S. wrote on Mon, 28 November 2011 09:31 |
Ken,
I did not replace the 5 amp fuse. The generator WILL fire up without the jumper in place. It just surges, and acts like it is running out of gas. It was almost a quart low on oil but filling it did not make any difference. It will rum smoothly with the jumper from 9 to 5. I will try Emery's suggestion when I get home. Leaving this morning.
Thanks to all who replied here or emailed me. This is a great group. Without the info provided here and other GMC sites, I would have had to get out the little construction generator I keep in the work truck.
Here are a couple of pics:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=41605
http://www.gmcmhphotos.com/photos/showphoto.php?photo=41602
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C. Boyd
76 Crestmont
East Tennessee
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| Re: Onan [message #150844 is a reply to message #150840] |
Mon, 28 November 2011 11:27 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Relay K3 has the contact that supplies the power to the fuel pump and ignition.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Onan [message #150846 is a reply to message #150844] |
Mon, 28 November 2011 11:39 |
UziYaH
Messages: 282
Registered: July 2007
Location: 10-O-C
Karma: 0
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Speaking of Onans, I'm having a bit of trouble with my starter engaging. Can I simply remove the starter without removing all the 'stuff' shown in the Onan manual? Thanks.
Howard N.
________________________________
From: Ken Burton <n9cv@comcast.net>
To: gmclist@temp.gmcnet.org
Sent: Monday, November 28, 2011 12:27 PM
Subject: Re: [GMCnet] Onan
Relay K3 has the contact that supplies the power to the fuel pump and ignition.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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Howard Nylander
Royale Class of "78" "Rocinate"
E-10-o-C
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| Re: [GMCnet] Onan [message #150855 is a reply to message #150849] |
Mon, 28 November 2011 12:13 |
UziYaH
Messages: 282
Registered: July 2007
Location: 10-O-C
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Mega thanks Emery!
Howard N.
________________________________
From: Emery Stora <emerystora@mac.com>
To: gmclist@temp.gmcnet.org
Sent: Monday, November 28, 2011 12:43 PM
Subject: Re: [GMCnet] Onan
On Nov 28, 2011, at 10:39 AM, Howard Nylander wrote:
> Speaking of Onans, I'm having a bit of trouble with my starter engaging. Can I simply remove the starter without removing all the 'stuff' shown in the Onan manual? Thanks.
>
> Howard N.
>
Sure -- just pull the battery cable off its terminal first and then remove the wires from the starter solenoid. Then there are two bolts that remove the starter.
Sometimes the starter engaging can be corrected by shimming a small washer between the starter bolt tab and the block. This will tilt the starter either toward the gear teeth or away from them depending on where you put the shim.
Emery Stora
77 Kingsley
Santa Fe, NM
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Howard Nylander
Royale Class of "78" "Rocinate"
E-10-o-C
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| Re: Onan [message #150907 is a reply to message #150840] |
Mon, 28 November 2011 20:35 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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| C Boyd wrote on Mon, 28 November 2011 08:14 |
Carl, soldered On the board is 2 retangular relays. one of these is a fuel pump power only when the gen is running. If this relay is weak or has dirty points it could cause your fuel pump to sputter when removing the 9-5 jumper. You can carefully pop the covers and visually check the relay in action. I have had limited luck trying to clean or adjust. There are rumors that a steady hand with a soldering iron can replace these relays.
would the manuals help?
http://bdub.net/manuals/index.html
|
Thanks Chuck, That could be it. I noticed some obvious arcing coming from under the upper relay cover, if that's the right one. I'll look into it. I'll try to diagnose it, using all of the suggestions from here, later in the week and report back.
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 [message #150911 is a reply to message #150907] |
Mon, 28 November 2011 20:46 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Another thing you might consider if it is an original board and you have time to mess with it. The original diodes have been known to fail. It is a good idea to solder in new heaver duty diodes in place of the originals. They are cheap at Radio Shack if they still sell them.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: Onan [message #151550 is a reply to message #150911] |
Sun, 04 December 2011 12:08 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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Back to my Onan. I just fired it up with the wire disconnected from the #12 terminal, and after it warmed up (it's only 44* in Tucson today) and I adjusted the carburetor (it was running rich - I am about 2300 ft above the elevation at the Dunes) it ran fine. No change when I re-connected the #12 terminal. There was a small amount of oil, a couple of drips, coming from the right side behind the filter. I believe this is where the LOP switch is located. I will replace the LOP switch, as I can't imagine it is a costly item, and see if that fixes the problem long range.
Thanks for all the helpful suggestions.
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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