| [GMCnet] Stick has a running Onan? [message #284397] |
Sun, 09 August 2015 12:29  |
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ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
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Senior Member |
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Ken,
Did I see that you and Stick got his Onan running? I suspect you didn’t let him into your coach for 2 reasons. The stated reason that he was too greasy, and the prudent (lunch saving) reason why you wouldn’t let him strip down to his shorts to go into the coach!
Congrats on the cruise control and congratulations to Stick on his working Onan. I wonder if all that grease could somehow find it’s way into my sore joints...
Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, CA
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Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
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| Re: [GMCnet] Stick has a running Onan? [message #284420 is a reply to message #284397] |
Sun, 09 August 2015 16:16  |
MikeT
Messages: 225
Registered: November 2009
Location: Marine City, Michigan
Karma: 0
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I've been watching the thread since it started. Please tell us how you fixed onan and cruise. I took onan carb apart, cleaned and and put back together. Also removed the one way electric check Valve. Started and it ran fine with load for 1.5 hours then died. Primed and started again for 5 minutes no load and died. Primed and started again and ran for two minutes died. Jumper from pos on starter to coil to eliminate circuit board with same result. Died in two minutes. Guess I'll take carb apart again and clean. I think it's fuel related. I have over 1/2 tank of gas.
Anxious to see what your fix was.
Thanks
Mike Thomas
Marine City, MI
77 ex Palm Beach
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| Re: [GMCnet] Stick has a running Onan? [message #284427 is a reply to message #284420] |
Sun, 09 August 2015 17:51 |
Jim Miller
Messages: 501
Registered: March 2008
Karma: 10
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Senior Member |
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On Aug 9, 2015, at 5:16 PM, Thomas Mike wrote:
>
> I've been watching the thread since it started. Please tell us how you fixed onan and cruise. I took onan carb apart, cleaned and and put back
> together. Also removed the one way electric check Valve. Started and it ran fine with load for 1.5 hours then died. Primed and started again for 5
> minutes no load and died. Primed and started again and ran for two minutes died. Jumper from pos on starter to coil to eliminate circuit board with
> same result. Died in two minutes. Guess I'll take carb apart again and clean. I think it's fuel related. I have over 1/2 tank of gas.
Did you have fuel in the bowl when it died? There are several possible failure modes in the fuel system but if the bowl is dry when the engine quits then you’ve positively determined that fuel delivery is the problem.
If you have a neon-bulb spark tester then put it in line with one of the plugs and watch it when the engine is running normally and pay particular attention when the engine starts to sputter and die. If the tester shows healthy and repetitive spark that decreases in rate as the engine winds down then you have extra assurance that it is a fuel issue. If the spark is ragged and inconsistent when it starts to sputter then you may have a heat-related issue in the ignition system.
You’ve ruled out the control board as the source of the problem by the use of the jumper - excellent!
BTW that’s not a electric check valve - it is a simple on/off electric valve that is there to prevent drainback to the tank after the generator is shut down. This gives the machine a small amount of fuel to start up and run with while the pump re-establishes its prime with fuel from the tank.
--Jim "saving the lives of Onans...one unit at a time" 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] Stick has a running Onan? [message #284428 is a reply to message #284420] |
Sun, 09 August 2015 18:07 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Stick didn't really have a running problem with his Onan -- just a starting
problem: The starter mounting bracket was, like so many, broken. It had
been poorly welded (there's probably no such thing as welding it well) so
he replaced it with the Ragusa version. With that in place, the Onan
started right up and ran well. But it's a GREASY one -- thus Stick's
condition. :-)
As for my cruise control, it was a simple correction of a wiring error I
made when I installed the ElectroMotor II several years ago: The brake
light circuit is used to disengage the CC. The way I had it wired, the
signal on that circuit could be indeterminate, making engagement sometimes
fail; I merely added a resistor to ensure the line is pulled to ground when
the brakes are not applied.
If you haven't gotten Dwayne Simmons' troubleshooting guides from
GMCWS.org, do so. Most of what I (used to) know about Onans came from
there.
Ken H.
On Sun, Aug 9, 2015 at 5:16 PM, Thomas Mike wrote:
> I've been watching the thread since it started. Please tell us how you
> fixed onan and cruise. I took onan carb apart, cleaned and and put back
> together. Also removed the one way electric check Valve. Started and it
> ran fine with load for 1.5 hours then died. Primed and started again for 5
> minutes no load and died. Primed and started again and ran for two minutes
> died. Jumper from pos on starter to coil to eliminate circuit board with
> same result. Died in two minutes. Guess I'll take carb apart again and
> clean. I think it's fuel related. I have over 1/2 tank of gas.
>
> Anxious to see what your fix was.
>
> Thanks
> --
> Mike Thomas
> Troy, MI
> 77 ex Palm Beach, 77 Royale (rear bath)
>
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> GMCnet mailing list
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Stick has a running Onan? [message #284443 is a reply to message #284420] |
Sun, 09 August 2015 22:04 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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MikeT wrote on Sun, 09 August 2015 14:16I've been watching the thread since it started. Please tell us how you fixed onan and cruise. I took onan carb apart, cleaned and and put back together. Also removed the one way electric check Valve. Started and it ran fine with load for 1.5 hours then died. Primed and started again for 5 minutes no load and died. Primed and started again and ran for two minutes died. Jumper from pos on starter to coil to eliminate circuit board with same result. Died in two minutes. Guess I'll take carb apart again and clean. I think it's fuel related. I have over 1/2 tank of gas.
Anxious to see what your fix was.
Thanks
A few years ago, my Onan was doing the same thing as yours. It would start and run just fine for a while then quit. It behaved this way with ever diminishing run times until it would only stay running for 10 - 15 minutes at a time. It would run until it warmed up and then quit. The fuel pump seemed to be working properly, but it wasn't. I replaced it with a Mr Gasket pump from Applied GMC, and the problem was solved, until recently. It did the same thing as before, for the first time in three years, on our recent trip, so I will have to start diagnosing it all over again. I guess it is possible that the fuel pump is the problem again, but it might be the ignition this time. These intermittent problems can drive a guy nuts.
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] Stick has a running Onan? [message #284446 is a reply to message #284420] |
Sun, 09 August 2015 22:43 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Mike,
See MM X-7525 / Section 24C - Onan Motor Generator / Page 24C-2 / Figure 3 - Onan Motor Generator (Left Side View) and you will see
the Electric Fuel Pump.
Turn to page 24C-24 and you'll find paragraph Fuel Pump Filter Element (Figure 35). I would suggest cleaning the filter.
Then go to Parts Book 78Z / Page 28-51 Figure 28.044E - Pump - Fuel, Onan Generator.
It shows two exploded views of the fuel pump; the top one shows how to remove the filter, the bottom one shows how to remove the
Plunger (Key 10). It is possible that when the fuel pump gets warm the plunger seizes.
Take it apart carefully and check the plunger and the bore it rides in for corrosion or baked on fuel varnish. Clean them if they
are.
Pay careful attention to the sequence Key numbers 5 through ten are in and put them back in so they are in the same sequence!
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: Thomas Mike
I've been watching the thread since it started. Please tell us how you fixed onan and cruise. I took onan carb apart, cleaned and
and put back together. Also removed the one way electric check Valve. Started and it ran fine with load for 1.5 hours then died.
Primed and started again for 5 minutes no load and died. Primed and started again and ran for two minutes died. Jumper from pos on
starter to coil to eliminate circuit board with same result. Died in two minutes. Guess I'll take carb apart again and clean. I
think it's fuel related. I have over 1/2 tank of gas.
Anxious to see what your fix was.
Thanks
--
Mike
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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