Home » Public Forums » GMCnet » Onan Woes (Let's beat this dead horse again.)
| Onan Woes [message #210486] |
Sun, 09 June 2013 16:35  |
stick miller
Messages: 1036
Registered: March 2010
Location: Americus, Georgia
Karma: 0
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I'm starting a new thread about my notionate (what a great Southern word) Onan. On the road, it runs for an hour or two or three then cuts off. The only way to start it is to jump the fuel pump to the battery and fill the bowl. In another thread I was told that it could be the coil or the fuel pump. I'm betting on the fuel pump.
Don't assume that I know anything about mechanical devices. So both the fuel pump and the coil can get hot and quit? I have a non OEM fuel pump that looks fairly new. The coil still has Onan green paint on it.
When I put power to the pump it will shoot gasoline across the room. Of course, I can't see what is happening when it gets hot. It IS hot here.
I started it today in my driveway and let it run 5 hours in extreme heat. Turned on both A/C units and used the vacuum cleaner and it never faltered. I finally shut it down when the neighbor asked me if I was ever going to finish cutting the grass.
When it does quit, it will immediately start again if I manually jump the fuel pump to the battery. If not, it will not self-prime.
It is not low on oil and it behaves the same if the coach has a full or half full tank of gasoline. I can see no obvious loose wires or shorts.
We have a North Georgia trip planned in July that will not happen without air conditioning.
Who or where is the source for coils, fuel pumps and air filters? My air filter is very dirty but I removed (temporarily) the PCV hose so I know it is getting air. I bet I could match up an air filter that might not be perfect, but that would fit. I really don't mind throwing parts at it. I just want it to work.
Thanks, in advance, for any help.
Stick Miller
'78 Royale - "White Trash" - she left me for another man
'76 Eleganza - "Cousin Eddie" Sold
'84 Bluebird Wanderlodge - "Past Tents"
Americus, GA
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| Re: [GMCnet] Onan Woes [message #210490 is a reply to message #210486] |
Sun, 09 June 2013 16:48  |
Robin Hood
Messages: 1078
Registered: April 2011
Karma: 3
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Senior Member |
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Stick, Napa and AutoZone both have a fuel pump, low-pressure, that will
work fine. As for a replacement coil, I got mine at a Harley-Davidson
motorcycle shop. That said, it sounds like your pump and your coil are
working. Do you still have that little solenoid upstream of your fuel pump?
Also for inspiration, you can always watch my horrible series of YouTube
videos where I work on my Onan. :-)
On Sunday, June 9, 2013, Stick Miller wrote:
>
>
> I'm starting a new thread about my notionate (what a great Southern word)
> Onan. On the road, it runs for an hour or two or three then cuts off. The
> only way to start it is to jump the fuel pump to the battery and fill the
> bowl. In another thread I was told that it could be the coil or the fuel
> pump. I'm betting on the fuel pump.
>
> Don't assume that I know anything about mechanical devices. So both the
> fuel pump and the coil can get hot and quit? I have a non OEM fuel pump
> that looks fairly new. The coil still has Onan green paint on it.
>
> When I put power to the pump it will shoot gasoline across the room. Of
> course, I can't see what is happening when it gets hot. It IS hot here.
>
> I started it today in my driveway and let it run 5 hours in extreme heat.
> Turned on both A/C units and used the vacuum cleaner and it never faltered.
> I finally shut it down when the neighbor asked me if I was ever going to
> finish cutting the grass.
>
> When it does quit, it will immediately start again if I manually jump the
> fuel pump to the battery. If not, it will not self-prime.
>
> It is not low on oil and it behaves the same if the coach has a full or
> half full tank of gasoline. I can see no obvious loose wires or shorts.
>
> We have a North Georgia trip planned in July that will not happen without
> air conditioning.
>
> Who or where is the source for coils, fuel pumps and air filters? My air
> filter is very dirty but I removed (temporarily) the PCV hose so I know it
> is getting air. I bet I could match up an air filter that might not be
> perfect, but that would fit. I really don't mind throwing parts at it. I
> just want it to work.
>
> Thanks, in advance, for any help.
>
> --
> Stick Miller
> '78 Royale - she left me for another man
> '76 Eleganza
> Americus, Georgia
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Robin Hood
Jackson, MS
2013 Subaru Outback "Top Flight"
1968 Pontiac Catalina "The Cheshire Cat"
1978 GMC Royale motorhome "Pinto Bean"
1977 GMC Palm Beach motorhome "Barn Queen"
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| Re: [GMCnet] Onan Woes [message #210492 is a reply to message #210486] |
Sun, 09 June 2013 16:56 |
Jim Miller
Messages: 501
Registered: March 2008
Karma: 10
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Senior Member |
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On Jun 9, 2013, at 5:35 PM, Stick Miller wrote:
> I'm starting a new thread about my notionate (what a great Southern word) Onan. On the road, it runs for an hour or two or three then cuts off. The only way to start it is to jump the fuel pump to the battery and fill the bowl. In another thread I was told that it could be the coil or the fuel pump. I'm betting on the fuel pump.
What about your control board? Is it original or very old?
Electrolytic and other types of capacitors are used throughout the board. Capacitors are notorious sources of failure in electronic gear especially gear that operates in high-heat environments. Considering that your board may be several tens of years old - coupled with the increasing heat in the onan compartment during a three hour run - it is very possible that you have a controls problem rather than a mechanical one.
We keep one of JimK's Dinosaur boards around as a spare to swap into Onans that misbehave.
In my opinion the Onans are displaying two age-related failures at this point in time - control boards and field windings. If an Onan comes in with no AC output the first task is to check the field windings - even before the bridge. If it displays other erratic behavior then temporarily swap control boards with a known good specimen and then re-evaluate. 90% of Onans we've seen over the past couple of years have had one of these two problems.
--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 Woes [message #210495 is a reply to message #210492] |
Sun, 09 June 2013 17:12 |
stick miller
Messages: 1036
Registered: March 2010
Location: Americus, Georgia
Karma: 0
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Senior Member |
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Thanks, Jim. I am not sure how I'd test the board unless I just order a new one. I did the pin 5-9 jump and everything seemed to be working as it should.
I have plenty of AC (as in alternating current - not air conditioning) output from the generator.
Stick Miller
'78 Royale - "White Trash" - she left me for another man
'76 Eleganza - "Cousin Eddie" Sold
'84 Bluebird Wanderlodge - "Past Tents"
Americus, GA
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| Re: [GMCnet] Onan Woes [message #210499 is a reply to message #210495] |
Sun, 09 June 2013 17:20 |
Jim Miller
Messages: 501
Registered: March 2008
Karma: 10
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Senior Member |
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On Jun 9, 2013, at 6:12 PM, Stick Miller wrote:
> I am not sure how I'd test the board unless I just order a new one. I did the pin 5-9 jump and everything seemed to be working as it should.
Vibration, heat and age are mortal enemies of electronic componentry. The onan control board was built cheaply to start with (no conformal coating, particularly) and I doubt they used components spec'd for high temps and high vibes. I think it is a miracle that any of the OEM boards still work.
You've already described that your Onan runs great if you defeat the control system with your jumper lead. That fact would lead me toward a controls problem.
The experts on the list will certainly have other avenues for you to explore. I'm just giving my $0.02.
> I have plenty of AC (as in alternating current - not air conditioning) output from the generator.
The control board does not participate in the AC generation function other than keeping the prime mover running.
--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 Woes [message #210510 is a reply to message #210490] |
Sun, 09 June 2013 18:48 |
Guy Lopes
Messages: 499
Registered: April 2004
Location: Sacramento, CA
Karma: 3
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Senior Member |
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Robin, Is your user name on YouTube goodluckfox?
Guy in Sacramento
Subject: Re: [GMCnet] Onan Woes
Stick, Napa and AutoZone both have a fuel pump, low-pressure, that will work
fine. As for a replacement coil, I got mine at a Harley-Davidson motorcycle
shop. That said, it sounds like your pump and your coil are working. Do you
still have that little solenoid upstream of your fuel pump?
Also for inspiration, you can always watch my horrible series of YouTube
videos where I work on my Onan. :-)
On Sunday, June 9, 2013, Stick Miller wrote:
>
>
> I'm starting a new thread about my notionate (what a great Southern
> word) Onan. On the road, it runs for an hour or two or three then cuts
> off. The only way to start it is to jump the fuel pump to the battery
> and fill the bowl. In another thread I was told that it could be the
> coil or the fuel pump. I'm betting on the fuel pump.
>
> Don't assume that I know anything about mechanical devices. So both
> the fuel pump and the coil can get hot and quit? I have a non OEM
> fuel pump that looks fairly new. The coil still has Onan green paint on
it.
>
> When I put power to the pump it will shoot gasoline across the room.
> Of course, I can't see what is happening when it gets hot. It IS hot here.
>
> I started it today in my driveway and let it run 5 hours in extreme heat.
> Turned on both A/C units and used the vacuum cleaner and it never
faltered.
> I finally shut it down when the neighbor asked me if I was ever going
> to finish cutting the grass.
>
> When it does quit, it will immediately start again if I manually jump
> the fuel pump to the battery. If not, it will not self-prime.
>
> It is not low on oil and it behaves the same if the coach has a full
> or half full tank of gasoline. I can see no obvious loose wires or shorts.
>
> We have a North Georgia trip planned in July that will not happen
> without air conditioning.
>
> Who or where is the source for coils, fuel pumps and air filters? My
> air filter is very dirty but I removed (temporarily) the PCV hose so I
> know it is getting air. I bet I could match up an air filter that
> might not be perfect, but that would fit. I really don't mind throwing
> parts at it. I just want it to work.
>
> Thanks, in advance, for any help.
>
> --
> Stick Miller
> '78 Royale - she left me for another man
> '76 Eleganza
> Americus, Georgia
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Robin Hood
Jackson, MS
2013 Subaru Outback "Top Flight"
1968 Pontiac Catalina "The Cheshire Cat"
1978 GMC Royale motorhome "Pinto Bean"
1977 GMC Palm Beach motorhome "Barn Queen"
_______________________________________________
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Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Guy Lopes
76 Birchaven "Orion"
Sacramento, CA
W6TOL
www.GMC-Guy.com
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| Re: [GMCnet] Onan Woes [message #210523 is a reply to message #210510] |
Sun, 09 June 2013 20:28 |
Robin Hood
Messages: 1078
Registered: April 2011
Karma: 3
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Senior Member |
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Yeah, that's me! Not all of my videos are that great. They can't all be
gems. :-)
On Sunday, June 9, 2013, Guy Lopes wrote:
> Robin, Is your user name on YouTube goodluckfox?
>
> Guy in Sacramento
>
>
>
> Subject: Re: [GMCnet] Onan Woes
>
> Stick, Napa and AutoZone both have a fuel pump, low-pressure, that will
> work
> fine. As for a replacement coil, I got mine at a Harley-Davidson motorcycle
> shop. That said, it sounds like your pump and your coil are working. Do you
> still have that little solenoid upstream of your fuel pump?
> Also for inspiration, you can always watch my horrible series of YouTube
> videos where I work on my Onan. :-)
>
> On Sunday, June 9, 2013, Stick Miller wrote:
>
> >
> >
> > I'm starting a new thread about my notionate (what a great Southern
> > word) Onan. On the road, it runs for an hour or two or three then cuts
> > off. The only way to start it is to jump the fuel pump to the battery
> > and fill the bowl. In another thread I was told that it could be the
> > coil or the fuel pump. I'm betting on the fuel pump.
> >
> > Don't assume that I know anything about mechanical devices. So both
> > the fuel pump and the coil can get hot and quit? I have a non OEM
> > fuel pump that looks fairly new. The coil still has Onan green paint on
> it.
> >
> > When I put power to the pump it will shoot gasoline across the room.
> > Of course, I can't see what is happening when it gets hot. It IS hot
> here.
> >
> > I started it today in my driveway and let it run 5 hours in extreme heat.
> > Turned on both A/C units and used the vacuum cleaner and it never
> faltered.
> > I finally shut it down when the neighbor asked me if I was ever going
> > to finish cutting the grass.
> >
> > When it does quit, it will immediately start again if I manually jump
> > the fuel pump to the battery. If not, it will not self-prime.
> >
> > It is not low on oil and it behaves the same if the coach has a full
> > or half full tank of gasoline. I can see no obvious loose wires or
> shorts.
> >
> > We have a North Georgia trip planned in July that will not happen
> > without air conditioning.
> >
> > Who or where is the source for coils, fuel pumps and air filters? My
> > air filter is very dirty but I removed (temporarily) the PCV hose so I
> > know it is getting air. I bet I could match up an air filter that
> > might not be perfect, but that would fit. I really don't mind throwing
> > parts at it. I just want it to work.
> >
> > Thanks, in advance, for any help.
> >
> > --
> > Stick Miller
> > '78 Royale - she left me for another man
> > '76 Eleganza
> > Americus, Georgia
> >
> >
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> >
>
>
> --
> Robin Hood
> Jackson, MS
> 2013 Subaru Outback "Top Flight"
> 1968 Pontiac Catalina "The Cheshire Cat"
> 1978 GMC Royale motorhome "Pinto Bean"
> 1977 GMC Palm Beach motorhome "Barn Queen"
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Robin Hood
Jackson, MS
2013 Subaru Outback "Top Flight"
1968 Pontiac Catalina "The Cheshire Cat"
1978 GMC Royale motorhome "Pinto Bean"
1977 GMC Palm Beach motorhome "Barn Queen"
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GMCnet mailing list
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