Home » Public Forums » GMCnet » [GMCnet] onan jumpers part 2
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| Re: [GMCnet] onan jumpers part 2 [message #133851 is a reply to message #133846] |
Fri, 08 July 2011 20:35   |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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David,
I believe the wires in your photo are those formerly connected to the
Voltage Regulator (VR) -- that's the finned aluminum device at the extreme
left top rear, just above the cylindrical fuel pump. There are three
terminals on the top of the VR. It is common practice to disconnect those
wires AND INSULATE THEM. One should be a single wire, the other should be
two wires attached to a common connector. You should tape those up and
henceforth ignore them. They were only applicable to coaches which had a
discrete battery to support only the Onan and can cause engine failure to
run.
The breakage of your Start/Stop switch is slightly more serious, but not
necessarily catastrophic. The R&R of the control board is not rocket
science, but don't attempt it without clearly identifying which wire goes to
each of the already well marked terminals on the board. Each wire should
have a legend but you'll probably have more success if you label them
yourself.
With the board removed, it should be relatively easy to repair the switch.
Otherwise, it's a simple SPDT-CO spring loaded switch. The common connects
to pin 1 of the board, one NO terminal to 2 for Stop and the other NO
terminal to 3 for Start. It's not necessary to find a switch to fit on the
board if you're willing to wire it to a remote location on the Onan. In
fact, if the switch is completely disabled, you should still be able to use
the remote control switch inside the coach.
The quickest way to determine whether the fuel pump is operating is to
connect a jumper wire from its connector to pin 9 of the control board (or
the ignition coil terminal connected to that pin. Until you get the pump to
clicking, the engine is unlikely to start.
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
On Fri, Jul 8, 2011 at 8:58 PM, David <75glenbrook@gmail.com> wrote:
> I lost my own thread, one of those days..
> here are the pics i had a question about
>
> http://www.gmcmhphotos.com/photos/showgallery.php?cat=500&ppuser=8289
>
> while troubleshooting, my start stop switch broke off the control board...
>
>
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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] onan jumpers part 2 [message #133975 is a reply to message #133853] |
Sat, 09 July 2011 19:39 |
Dave Motorhome
Messages: 175
Registered: July 2007
Karma: 2
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Senior Member |
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so i was able to work on it tonight, I bypassed the circuit board and
just ran 12 volt straight to the fuel pump, fuel pump ran just fine. I
also rechecked my circuit board volts and was having a real hard time
getting any current, so i will clean all terminals, but does this seem
to lead to a bad board?
David Paliotta
75 Glenbrook
Tulsa, OK
http://75glenbrook.googlepages.com/
On Fri, Jul 8, 2011 at 8:47 PM, Dennis Sexton <dennisfsexton@aol.com> wrote:
>
>
> Dave,
>
> Here is your original thread...
>
> http://goo.gl/XW6rr
>
> Dennis
> --
> Dennis S
> 73 Painted Desert 230
> Germantown, TN
> _______________________________________________
> GMCnet mailing list
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| Re: [GMCnet] onan jumpers part 2 [message #133976 is a reply to message #133975] |
Sat, 09 July 2011 19:53 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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| Dave Motorhome wrote on Sat, 09 July 2011 19:39 |
so i was able to work on it tonight, I bypassed the circuit board and
just ran 12 volt straight to the fuel pump, fuel pump ran just fine. I
also rechecked my circuit board volts and was having a real hard time
getting any current, so i will clean all terminals, but does this seem
to lead to a bad board?
David Paliotta
75 Glenbrook
Tulsa, OK
http://75glenbrook.googlepages.com/
|
Dave,
What was the source of the 12 volts you used to run the fuel pump? Might you have a weak battery or poor connection from the Onan starting battery to the Onan?
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] onan jumpers part 2 [message #133978 is a reply to message #133976] |
Sat, 09 July 2011 20:12 |
Dave Motorhome
Messages: 175
Registered: July 2007
Karma: 2
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Senior Member |
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brand new battery, seems to be ~ close to 12.5 from post to post, from
neg to starter seems again real close to 12.5 maybe 12.4. she tries to
run .
i ran a line to the fuel pump from the battery and i can here the
fuel pump click. when i jump 9 to 5 nothing on the fuel pump.
i then tried what i tried yesterday, just use the volt meter on the
board itself, 9 to 5 to get some measurement, today i did not get any,
yesterday i got some reading but was tricky.
David Paliotta
75 Glenbrook
Tulsa, OK
http://75glenbrook.googlepages.com/
On Sat, Jul 9, 2011 at 7:53 PM, Dennis Sexton <dennisfsexton@aol.com> wrote:
>
>
> Dave Motorhome wrote on Sat, 09 July 2011 19:39
>> so i was able to work on it tonight, I bypassed the circuit board and
>> just ran 12 volt straight to the fuel pump, fuel pump ran just fine. I
>> also rechecked my circuit board volts and was having a real hard time
>> getting any current, so i will clean all terminals, but does this seem
>> to lead to a bad board?
>>
>> David Paliotta
>> 75 Glenbrook
>> Tulsa, OK
>> http://75glenbrook.googlepages.com/
>
>
> Dave,
>
> What was the source of the 12 volts you used to run the fuel pump? Might you have a weak battery or poor connection from the Onan starting battery to the Onan?
>
> Dennis
> --
> Dennis S
> 73 Painted Desert 230
> Germantown, TN
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] onan jumpers part 2 [message #133985 is a reply to message #133978] |
Sat, 09 July 2011 20:28 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Dave,
It seems to me that the problem has to be in getting power to the board (doesn't mean you don't also have a board problem). Jumping 5 and 9 removes the board function from the equation --
Check for voltage at the starter -- where the heavy cable connects.
Dennis
Dennis S
73 GMC
Germantown, TN
USA
-----Original Message-----
From: David <75glenbrook@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Sat, Jul 9, 2011 8:12 pm
Subject: Re: [GMCnet] onan jumpers part 2
brand new battery, seems to be ~ close to 12.5 from post to post, from
eg to starter seems again real close to 12.5 maybe 12.4. she tries to
un .
ran a line to the fuel pump from the battery and i can here the
uel pump click. when i jump 9 to 5 nothing on the fuel pump.
i then tried what i tried yesterday, just use the volt meter on the
oard itself, 9 to 5 to get some measurement, today i did not get any,
esterday i got some reading but was tricky.
David Paliotta
5 Glenbrook
ulsa, OK
ttp://75glenbrook.googlepages.com/
On Sat, Jul 9, 2011 at 7:53 PM, Dennis Sexton <dennisfsexton@aol.com> wrote:
Dave Motorhome wrote on Sat, 09 July 2011 19:39
> so i was able to work on it tonight, I bypassed the circuit board and
> just ran 12 volt straight to the fuel pump, fuel pump ran just fine. I
> also rechecked my circuit board volts and was having a real hard time
> getting any current, so i will clean all terminals, but does this seem
> to lead to a bad board?
>
> David Paliotta
> 75 Glenbrook
> Tulsa, OK
> http://75glenbrook.googlepages.com/
Dave,
What was the source of the 12 volts you used to run the fuel pump? Might you
ave a weak battery or poor connection from the Onan starting battery to the
nan?
Dennis
--
Dennis S
73 Painted Desert 230
Germantown, TN
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MCnet mailing list
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Dennis S
73 Painted Desert 230
Memphis TN Metro
[Updated on: Sat, 09 July 2011 20:31] Report message to a moderator |
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| Re: [GMCnet] onan jumpers part 2 [message #133990 is a reply to message #133987] |
Sat, 09 July 2011 20:36 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Dave,
Good, now trace/follow the smaller wires from the starter terminal where you get 12.5 volts and see which one goes to the control board. Check voltage at that point -- maybe a bad wire or bad connector at one end.
Dennis
Dennis S
73 GMC
Germantown, TN 38138-2066
USA
-----Original Message-----
From: David <75glenbrook@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Sat, Jul 9, 2011 8:32 pm
Subject: Re: [GMCnet] onan jumpers part 2
from battery neg to starter pos it is 12.4 12.5 (my voltmeter is analog)
David Paliotta
5 Glenbrook
ulsa, OK
ttp://75glenbrook.googlepages.com/
On Sat, Jul 9, 2011 at 8:28 PM, As <dennisfsexton@aol.com> wrote:
Dave,
It seems to me that the problem has to be in getting power to the board
doen't mean you don't also have a board problem). Jumping 5 and 9 removes the
oard function from the --
Check for voltage at the starter -- where the heavy cable connects.
Dennis
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MCnet mailing list
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] onan jumpers part 2 [message #133991 is a reply to message #133987] |
Sat, 09 July 2011 20:52 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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| Dave Motorhome wrote on Sat, 09 July 2011 20:32 |
from battery neg to starter pos it is 12.4 12.5 (my voltmeter is analog)
David Paliotta
75 Glenbrook
Tulsa, OK
http://75glenbrook.googlepages.com/
|
Dave,
Also, double check the 5amp fuse on the control board. Just to be sure replace it if you have a known-good spare.
That fuse does have to be good for jumping 5 and 9 to work.
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] onan jumpers part 2 [message #133995 is a reply to message #133991] |
Sat, 09 July 2011 20:59 |
Dave Motorhome
Messages: 175
Registered: July 2007
Karma: 2
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Senior Member |
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i ran out of light, (wish i had a generator) but i just was out there,
and yesterday my start/ stop switch broke. i was looking at the cables
and it triggered a start (did not run) but i have to also repair the
start stop. but you seem to be right, maybe a short somewhere.
from the starter it seems to have 2 lines going toward the circuit
board, i will trace both.
thanks a lot for all your help.
David Paliotta
75 Glenbrook
Tulsa, OK
http://75glenbrook.googlepages.com/
On Sat, Jul 9, 2011 at 8:52 PM, Dennis Sexton <dennisfsexton@aol.com> wrote:
>
>
> Dave Motorhome wrote on Sat, 09 July 2011 20:32
>> from battery neg to starter pos it is 12.4 12.5 (my voltmeter is analog)
>>
>> David Paliotta
>> 75 Glenbrook
>> Tulsa, OK
>> http://75glenbrook.googlepages.com/
>
>
> Dave,
>
> Also, double check the 5amp fuse on the control board. Just to be sure replace it if you have a known-good spare.
> That fuse does have to be good for jumping 5 and 9 to work.
>
> Dennis
>
> --
> Dennis S
> 73 Painted Desert 230
> Germantown, TN
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] onan jumpers part 2 [message #133996 is a reply to message #133995] |
Sat, 09 July 2011 21:05 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Dave,
We may need one of the "strong on Onan electrics" to help with this..
Checking wires and connections -- and following the general trouble-shooting is generally my limit.
Look forward to hearing what you see/learn with daylight tomorrow.
Dennis
Dennis S
73 GMC
Germantown, TN
USA
-----Original Message-----
From: David <75glenbrook@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Sat, Jul 9, 2011 8:59 pm
Subject: Re: [GMCnet] onan jumpers part 2
i ran out of light, (wish i had a generator) but i just was out there,
nd yesterday my start/ stop switch broke. i was looking at the cables
nd it triggered a start (did not run) but i have to also repair the
tart stop. but you seem to be right, maybe a short somewhere.
rom the starter it seems to have 2 lines going toward the circuit
oard, i will trace both.
thanks a lot for all your help.
David Paliotta
5 Glenbrook
ulsa, OK
ttp://75glenbrook.googlepages.com/
On Sat, Jul 9, 2011 at 8:52 PM, Dennis Sexton <dennisfsexton@aol.com> wrote:
Dave Motorhome wrote on Sat, 09 July 2011 20:32
> from battery neg to starter pos it is 12.4 12.5 (my voltmeter is analog)
>
> David Paliotta
> 75 Glenbrook
> Tulsa, OK
> http://75glenbrook.googlepages.com/
Dave,
Also, double check the 5amp fuse on the control board. Just to be sure replace
t if you have a known-good spare.
That fuse does have to be good for jumping 5 and 9 to work.
Dennis
--
Dennis S
73 Painted Desert 230
Germantown, TN
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] onan jumpers part 2 [message #134657 is a reply to message #134602] |
Thu, 14 July 2011 20:37 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Today another GMCer mentioned that he's also been through 3 Onan
control boards, 2 of them Dinosaur. I promised to let him know if
y'all report anything from Ken B's investigations, or Dinosaur's.
From our discussions, I'm very suspicious of the coil in each case. I
just don't see how anything else can damage the boards since nothing
else is capable of drawing much current without an obvious failure.
Please keep us posted.
Oh yeah, another long-time GMCer, Mechanical Engineer with automotive
engineering experience, arrived with a just-failed Onan which had run
fine for the previous 3+ hours. While he was signing into the
campground, the Onan started "knocking" and his wife shut it down.
He'd started it and it ran very poorly. He'd gotten to the point of
pulling the plugs and wanted to know if I had, or would go with him to
buy, a compression gauge.
The next door GMCer, an experienced mechanic, and I, convinced him we
could stick a finger in the spark plug hole and tell closely enough
whether compression was low enough to cause his problem. I WAGed 100+
psi when we tried it. The plugs showed it was running very rich, as
did the exhaust when running.
With compression, fuel, and spark, we suggested he adjust the carb
mixture. Turning the low speed jet all the way to the seat made no
difference. Turning the high speed jet all the way to the seat made
no difference. Hmmmm...
Yep, he'd been working on the carburetor -- thorough cleaning in carb
cleaner. Plus, for some reason, a new fuel pump. When I questioned
him closely, he admitted that he found a foreign, Viton-tipped, needle
valve when he disassembled it, and the float badly adjusted. When he
disassembled it again today, he found the needle valve jammed and had
to modify it by scrapping its sides to reduce the diameter. In other
words, the float couldn't staunch the gasoline flow -- it probably
could that from the old fuel pump, causing the engine to not run
before he installed the new pump.
With the carburetor re-installed, the Onan started and ran great.
Until he re-installed the air cleaner; then, it almost died. Yep, the
cleaner was that badly clogged.
Needless to say, he was a bit embarrassed. He is, after all, a 30+
year GMC owner, former Chrysler & Boeing engineer, recent
self-installer of a Cad500, LOTS of mechanical experience, etc. It
happens to the best of us!!!
Ken H.
On Thu, Jul 14, 2011 at 3:43 PM, David wrote:
> Just to close this thread, i received my new board from Jim. plugged
> it in and the onan is running better than ever. thanks to all for your
> help
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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] onan jumpers part 2 [message #134660 is a reply to message #134657] |
Thu, 14 July 2011 20:59 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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| Ken Henderson wrote on Thu, 14 July 2011 20:37 |
Today another GMCer mentioned that he's also been through 3 Onan
control boards, 2 of them Dinosaur. I promised to let him know if
y'all report anything from Ken B's investigations, or Dinosaur's.
From our discussions, I'm very suspicious of the coil in each case. I
just don't see how anything else can damage the boards since nothing
else is capable of drawing much current without an obvious failure.
Please keep us posted.
|
I talked to someone named Chad at Dinosaur and they would not send me a diagram of their board. They agreed to trouble shoot George's board and tell us what failed. I explained to them that either they had a bad design to cause 3 board failures or there was something external to the board causing the failure. Without knowing what was failing on the board it was impossible to tell what the real problem was.
I agree that the problem is probably a coil or fuel pump drawing too much but one would think that they designed their circuit with relay points to handle at least 5 amps which is what the fuse on the board should be. I probably should throw an ammeter on my coil and pump to see what they draw. I know the HEI on the main engine draws a little less than 1.5 amps. I can not imagine the Onan drawing more than that.
George should be mailing the most recent board to them. Let's see what they say.
Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] onan jumpers part 2 [message #134664 is a reply to message #134661] |
Thu, 14 July 2011 21:02 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Yes that should be 28 to 31 volts but I can not see how that would burn out a board. That just tells the board when the engine is running. Go ahead and check it to keep them happy.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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