Home » Public Forums » GMCnet » Mr. Onan (No Spark)
| Mr. Onan [message #223842] |
Sat, 28 September 2013 09:31  |
Steve
Messages: 506
Registered: September 2013
Location: East Greenville, Pa
Karma: 1
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Senior Member |
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I have exhausted my knowledge and research on trying to get the Onan to fire. Recently new to me. Sat for five years. PO said they had used it and had paperwork for repairs including new starter and starting solenoid. Both were visibly new but ultimately tested bad. I am no expert but have worked on every type of engine including; lawn and power equipment, chain saws, motor cycles, snow mobiles, cars, truck, tractors, combines, etc. I have never not been able to get spark until I met Mr. Onan.
Onan would not even crank so I went through the trouble shooting guide in the service manual. Check voltage, jump this, jump that, etc. Test indicated bad starter. I got a second Onan from Sean Kid (Thank you very much), so I swapped out the starter and it cranks but no spark.
On to the "Control" section of the service manual. Everything tests ok except for the starting solenoid. Only 7.5 volts when cranking. Swapped out the solenoid and still only 7.5 volts when cranking and no spark. I have systematically tried all replaced all components of the control system including; the board (Onan boards, not Gorilla), starting solenoid and coil. No spark so on to the ignition section.
Here it gets interesting. I was able to get a single spark. When you you push the start button I would get a single spark and then no more. Release the button, try again and one single spark. I have tried the original points and condenser, donor points and condenser, and new points and condenser. Got the single spark from old points, donor points, but not new points?
Not sure what to do now, but I suspect possibly the oil sensor circuit? I don't know what direction that circuit fails, safe or otherwise. I just thought about it this morning. I am going to remove wire 12 from the oil circuit and see if that does it. I am hoping that a failed oil circuit was killing the spark after one spark?
Any thoughts or ideas would be appreciated?
I am tempted to order the Gorilla board but I understand Onan dealers won't work on them and this one may be headed to the dealer if I can't make it spark. My other option is to swap in the entire donor Onan and go that route, but it made sense to me to try and get the existing Onan to run first.
I carry a Honda 2000 in my truck camper and have a properly sized smaller AC unit that work well together but the 2000 won't drive a full size AC unit. I can carry the 2000 for basic electric but will need Mr. Onan for AC duty.
1978 GMC Royal
Eastern Pennslyvania
1968 Chevrolet C20 396 Camper Special
1969 Chevrolet C20 Camper Special
1985 Buick Electra Park Avenue
1992 Camaro 25th Anniversary Heretage Edition Black
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| Re: [GMCnet] Mr. Onan [message #223843 is a reply to message #223842] |
Sat, 28 September 2013 09:40  |
Mike Teets
Messages: 299
Registered: January 2004
Location: Dublin, OH
Karma: 0
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Senior Member |
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I think you will find that getting an Onan dealer to flip open the spring
latches and slide your unit open for inspection will cost about the same as
buying a new control board from one of the Jims.
On Sat, Sep 28, 2013 at 10:31 AM, Steve Adams <sjadams@ptd.net> wrote:
>
>
> I have exhausted my knowledge and research on trying to get the Onan to
> fire. Recently new to me. Sat for five years. PO said they had used it
> and had paperwork for repairs including new starter and starting solenoid.
> Both were visibly new but ultimately tested bad. I am no expert but have
> worked on every type of engine including; lawn and power equipment, chain
> saws, motor cycles, snow mobiles, cars, truck, tractors, combines, etc. I
> have never not been able to get spark until I met Mr. Onan.
>
> Onan would not even crank so I went through the trouble shooting guide in
> the service manual. Check voltage, jump this, jump that, etc. Test
> indicated bad starter. I got a second Onan from Sean Kid (Thank you very
> much), so I swapped out the starter and it cranks but no spark.
>
> On to the "Control" section of the service manual. Everything tests ok
> except for the starting solenoid. Only 7.5 volts when cranking. Swapped
> out the solenoid and still only 7.5 volts when cranking and no spark. I
> have systematically tried all replaced all components of the control system
> including; the board (Onan boards, not Gorilla), starting solenoid and
> coil. No spark so on to the ignition section.
>
> Here it gets interesting. I was able to get a single spark. When you you
> push the start button I would get a single spark and then no more. Release
> the button, try again and one single spark. I have tried the original
> points and condenser, donor points and condenser, and new points and
> condenser. Got the single spark from old points, donor points, but not new
> points?
>
> Not sure what to do now, but I suspect possibly the oil sensor circuit? I
> don't know what direction that circuit fails, safe or otherwise. I just
> thought about it this morning. I am going to remove wire 12 from the oil
> circuit and see if that does it. I am hoping that a failed oil circuit was
> killing the spark after one spark?
>
> Any thoughts or ideas would be appreciated?
>
> I am tempted to order the Gorilla board but I understand Onan dealers
> won't work on them and this one may be headed to the dealer if I can't make
> it spark. My other option is to swap in the entire donor Onan and go that
> route, but it made sense to me to try and get the existing Onan to run
> first.
>
> I carry a Honda 2000 in my truck camper and have a properly sized
> smaller AC unit that work well together but the 2000 won't drive a full
> size AC unit. I can carry the 2000 for basic electric but will need Mr.
> Onan for AC duty.
> --
> 1978 GMC Royal
> 1968 Chevrolet C20 396 Camper Special
> 1969 Chevrolet C20 Camper Special
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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Mike, GMCing since 2002
77 Palm Beach, 260, 403
Dublin, OH
http://teamteets.com/gmc/
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| Re: Mr. Onan [message #223846 is a reply to message #223842] |
Sat, 28 September 2013 10:10 |
Steve
Messages: 506
Registered: September 2013
Location: East Greenville, Pa
Karma: 1
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Senior Member |
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I pulled the number 12 wire and there is spark! Beautiful spark, jumping the gap, bright blue. I can't believe it was that simple. I probably have 10 hours in the Onan project. I will have to check the wiring on the oil circuit and possibly swap out the oil sensor, maybe even check the oil level again.
Ok, step one was make it crank. Step two is to make spark. On to step three to see if we can make it run. Who knows what the condition of the carb is or whether the fuel pump will function properly. At least I have spares for testing. Once running, will it make electricity?
As others have suggested, I will avoid the dealer whenever possible. I wish Onan would have put the number 12 wire test in its trouble shooting sequence.
1978 GMC Royal
Eastern Pennslyvania
1968 Chevrolet C20 396 Camper Special
1969 Chevrolet C20 Camper Special
1985 Buick Electra Park Avenue
1992 Camaro 25th Anniversary Heretage Edition Black
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| Re: [GMCnet] Mr. Onan [message #223847 is a reply to message #223842] |
Sat, 28 September 2013 10:10 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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The gap for the Onan is 0.020. If you need plugs go download the latest updated Spark Plug Application Guide and the second page is a large list of usable plug for the onan.
http://www.gmcmhphotos.com/photos/gmc-part-numbers/p50829-latest-spark-listing-u.html
JR Wright
78 Buskirk Stretch
75 Avion
Michigan
On Sep 28, 2013, at 10:31 AM, Steve Adams <sjadams@ptd.net> wrote:
>
>
> I have exhausted my knowledge and research on trying to get the Onan to fire. Recently new to me. Sat for five years. PO said they had used it and had paperwork for repairs including new starter and starting solenoid. Both were visibly new but ultimately tested bad. I am no expert but have worked on every type of engine including; lawn and power equipment, chain saws, motor cycles, snow mobiles, cars, truck, tractors, combines, etc. I have never not been able to get spark until I met Mr. Onan.
>
> Onan would not even crank so I went through the trouble shooting guide in the service manual. Check voltage, jump this, jump that, etc. Test indicated bad starter. I got a second Onan from Sean Kid (Thank you very much), so I swapped out the starter and it cranks but no spark.
>
> On to the "Control" section of the service manual. Everything tests ok except for the starting solenoid. Only 7.5 volts when cranking. Swapped out the solenoid and still only 7.5 volts when cranking and no spark. I have systematically tried all replaced all components of the control system including; the board (Onan boards, not Gorilla), starting solenoid and coil. No spark so on to the ignition section.
>
> Here it gets interesting. I was able to get a single spark. When you you push the start button I would get a single spark and then no more. Release the button, try again and one single spark. I have tried the original points and condenser, donor points and condenser, and new points and condenser. Got the single spark from old points, donor points, but not new points?
>
> Not sure what to do now, but I suspect possibly the oil sensor circuit? I don't know what direction that circuit fails, safe or otherwise. I just thought about it this morning. I am going to remove wire 12 from the oil circuit and see if that does it. I am hoping that a failed oil circuit was killing the spark after one spark?
>
> Any thoughts or ideas would be appreciated?
>
> I am tempted to order the Gorilla board but I understand Onan dealers won't work on them and this one may be headed to the dealer if I can't make it spark. My other option is to swap in the entire donor Onan and go that route, but it made sense to me to try and get the existing Onan to run first.
>
> I carry a Honda 2000 in my truck camper and have a properly sized smaller AC unit that work well together but the 2000 won't drive a full size AC unit. I can carry the 2000 for basic electric but will need Mr. Onan for AC duty.
> --
> 1978 GMC Royal
> 1968 Chevrolet C20 396 Camper Special
> 1969 Chevrolet C20 Camper Special
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] Mr. Onan [message #223878 is a reply to message #223846] |
Sat, 28 September 2013 13:04 |
Jim Bounds
Messages: 842
Registered: January 2004
Karma: 0
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Senior Member |
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Glad to see you hit on something, good job. You may want to also consider a backup if that 30 something year old board acts up again. Onan put it all on the one board so you can simply swap the board and take care of many possible electrical issues. But of course that would mean carrying an extra board all the time and who has bucks for that.
If you go to my web site and click on the "information " page. Scroll down to "Onan prime circuit", you will see how you can easily "hot wire" your generator to run from inside the coach at the remote panel. This circuit is also a great help under regular starting with a good board in that it supplies a hotter voltage during the start cycle. These elderly machine can use all the help they can get.
Hope this helps,
Jim Bounds
----------------------
________________________________
From: Steve Adams <sjadams@ptd.net>
To: gmclist@temp.gmcnet.org
Sent: Saturday, September 28, 2013 11:10 AM
Subject: Re: [GMCnet] Mr. Onan
I pulled the number 12 wire and there is spark! Beautiful spark, jumping the gap, bright blue. I can't believe it was that simple. I probably have 10 hours in the Onan project. I will have to check the wiring on the oil circuit and possibly swap out the oil sensor, maybe even check the oil level again.
Ok, step one was make it crank. Step two is to make spark. On to step three to see if we can make it run. Who knows what the condition of the carb is or whether the fuel pump will function properly. At least I have spares for testing. Once running, will it make electricity?
As others have suggested, I will avoid the dealer whenever possible. I wish Onan would have put the number 12 wire test in its trouble shooting sequence.
--
1978 GMC Royal
1968 Chevrolet C20 396 Camper Special
1969 Chevrolet C20 Camper Special
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| Re: [GMCnet] Mr. Onan [message #223888 is a reply to message #223842] |
Sat, 28 September 2013 15:36 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Single spark says there's twelve volts on the col alla time... not being interrupted by the points. Put your voltmeter on the points side of the coil. Should show pulsating voltage as the engine spins. If it does not, find out why. Voltage all the time = points never ground it. Voltage none of the time = ponits stay grounded. Out of adjustment, shorted or open capacitor, shorted or open wire to the breaker plate. Can be as simple as a bad ground, as troubleso0me as an open wire insuide the insulation.
--johnny
'76 23' transmode norris
'76 palm beach
--------------------------------------------
On Sat, 9/28/13, Steve Adams <sjadams@ptd.net> wrote:
Subject: [GMCnet] Mr. Onan
To: gmclist@temp.gmcnet.org
Date: Saturday, September 28, 2013, 2:31 PM
I have exhausted my knowledge and research on trying to get
the Onan to fire. Recently new to me. Sat for
five years. PO said they had used it and had paperwork
for repairs including new starter and starting solenoid.
Both were visibly new but ultimately tested bad. I am
no expert but have worked on every type of engine
including; lawn and power equipment, chain saws, motor
cycles, snow mobiles, cars, truck, tractors, combines,
etc. I have never not been able to get spark until I
met Mr. Onan.
Onan would not even crank so I went through the trouble
shooting guide in the service manual. Check voltage,
jump this, jump that, etc. Test indicated bad
starter. I got a second Onan from Sean Kid (Thank you
very much), so I swapped out the starter and it cranks but
no spark.
On to the "Control" section of the service manual.
Everything tests ok except for the starting solenoid.
Only 7.5 volts when cranking. Swapped out the solenoid and
still only 7.5 volts when cranking and no spark. I have
systematically tried all replaced all components of the
control system including; the board (Onan boards, not
Gorilla), starting solenoid and coil. No spark so on
to the ignition section.
Here it gets interesting. I was able to get a single
spark. When you you push the start button I would get
a single spark and then no more. Release the button,
try again and one single spark. I have tried the
original points and condenser, donor points and condenser,
and new points and condenser. Got the single spark
from old points, donor points, but not new points?
Not sure what to do now, but I suspect possibly the oil
sensor circuit? I don't know what direction that
circuit fails, safe or otherwise. I just thought about
it this morning. I am going to remove wire 12 from the
oil circuit and see if that does it. I am hoping that
a failed oil circuit was killing the spark after one spark?
Any thoughts or ideas would be appreciated?
I am tempted to order the Gorilla board but I understand
Onan dealers won't work on them and this one may be headed
to the dealer if I can't make it spark. My other
option is to swap in the entire donor Onan and go that
route, but it made sense to me to try and get the existing
Onan to run first.
I carry a Honda 2000 in my truck camper and have a properly
sized smaller AC unit that work well
together but the 2000 won't drive a full size AC unit.
I can carry the 2000 for basic electric but will need Mr.
Onan for AC duty.
--
1978 GMC Royal
1968 Chevrolet C20 396 Camper Special
1969 Chevrolet C20 Camper Special
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Unsubscribe or Change List Options:
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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: Mr. Onan [message #223909 is a reply to message #223842] |
Sat, 28 September 2013 20:19 |
Steve
Messages: 506
Registered: September 2013
Location: East Greenville, Pa
Karma: 1
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Senior Member |
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Many thanks to everyone who offered advice here. It is great to have others help you think through things. I was pretty discouraged after many hours with no success. Today went much better. I was able to get spark by disabling the low oil shut down circuit.
Onan is running now and producing 120 volts. I adjusted to that voltage by plugging in my multi-meter in the rear bath and reading it through the window as I made adjustments to the RPM. While the Onan is running, it is not completely running on its own. I was not able to get the fuel pump to work, so I am running from an auxiliary fuel tank sitting on a stack of buckets to gravity feed gas to the carb. (gravity is one of the few free things in life).
I think this will bring this post to a close and I will post a new one relating to options for the fuel pump. I do have a donor pump from the spare Onan but the wiring is very different. My 78 pump has four wires, while the 73 pump has only two wires. My instincts tell me to replace the pump with something new and modern rather than just swapping 35-40 year old parts. The swapping was great for trouble shooting but I would prefer to just build in reliability wherever possible.
In addition to finding the best option for a replacement fuel pump I also need to work on further adjusting the RPM and voltage output. The mechanism seems to be stuck. It did not throttle up to maintain RPM when I put a load on it. It does not feel as free as it should be. I will have to get it free and research the proper adjustment.
Jim B, I am a big fan of carrying spares. It reminds me of when we used to carry a spare set of points and condenser in the glove box of the truck. I am already making a list of spares to assemble and it will include points, condenser, and spare board for the Onan. For the coach it will include complete distributor, belts, radiator hoses, and likely alternator. Small dollars but acts as an insurance policy. If you have them you will never need them. If you don't have them they will all fail.
Thanks to everyone for the help. I will start a new topic when I can get back to the fuel pump and RPM adjustment. I am just realy happy Mr. Onan runs and produces power.
1978 GMC Royal
Eastern Pennslyvania
1968 Chevrolet C20 396 Camper Special
1969 Chevrolet C20 Camper Special
1985 Buick Electra Park Avenue
1992 Camaro 25th Anniversary Heretage Edition Black
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| Re: Mr. Onan [message #223914 is a reply to message #223842] |
Sat, 28 September 2013 20:30 |
Steve
Messages: 506
Registered: September 2013
Location: East Greenville, Pa
Karma: 1
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Senior Member |
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One more thought on carrying spares. I am a very big fan of having spares for the RV. If you read my account signature you will note that I "carry" a spare truck for my other RV. Well, I guess I don't really carry it but I keep a spare truck for the truck camper in case it is needed in an emergency. It is like having 100% redundant drive train and mechanical's for the RV.
1978 GMC Royal
Eastern Pennslyvania
1968 Chevrolet C20 396 Camper Special
1969 Chevrolet C20 Camper Special
1985 Buick Electra Park Avenue
1992 Camaro 25th Anniversary Heretage Edition Black
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| Re: Mr. Onan [message #223916 is a reply to message #223842] |
Sat, 28 September 2013 20:47 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Steve,
You are on the right track, but there are some switches that you need to pay attention to....
That Bendix(Facet) clicker pump is DC3 reliable, but it may need maintenance. This is easy and near zero cost. I am on the road or I would send you the files, but dig around on the web and you can find them.
The points in an Onan are the worst part, but again, dig through the GMCnet stuff for Onan/Pertronix re-fit. This gets rid of the points and then it will be a much happier machine.
The new LOP switch is available at NAPA but I don't remember the number, it is in the GMCMI parts book - if you are a member.....
The 6KW NH tends to beat up the mounts, if you run it that way things will get broken. Expensive things..
Finally (aren't you glad), go get a thing called a "Kill-A-Watt" (available at lots of big box stores) and a short extension cord. When tuning the Onan, plug in the cord and throw it out a convenient window. The KAW can read out voltage and frequency. Between those two, you can set the Onan up to purr like a happy kitten. <Aside - KAW come in models 4400 or 4460, either will work for you.)
(Do I have to say Been There - Done That?)
Matt - Hold up just short of Nashville.
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: Mr. Onan [message #223917 is a reply to message #223916] |
Sat, 28 September 2013 21:02 |
Steve
Messages: 506
Registered: September 2013
Location: East Greenville, Pa
Karma: 1
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Senior Member |
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Thanks Matt,
I will look into the maintenance items and testing on the fuel pump. I would also consider moving to electronic ignition at some point for the Onan. I was not willing to spend $120 to $150 for the conversion when I was not sure of the condition of the gen or other major systems of the coach. I also need to check and re-wire the remote controls as I think those wires got severed somehow and were dangling below the coach. Lots of work already and lots of fun ahead. Interesting that you would mention mounts. I noticed that my spare donor Onan had new mounts. I guess I better swap those out. I will add to my to do list.
1978 GMC Royal
Eastern Pennslyvania
1968 Chevrolet C20 396 Camper Special
1969 Chevrolet C20 Camper Special
1985 Buick Electra Park Avenue
1992 Camaro 25th Anniversary Heretage Edition Black
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| Re: [GMCnet] Mr. Onan [message #223960 is a reply to message #223913] |
Sun, 29 September 2013 08:36 |
Jim Miller
Messages: 501
Registered: March 2008
Karma: 10
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Senior Member |
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On Sep 28, 2013, at 9:30 PM, Dan Gregg wrote:
> Great Steve. The cost of those parts is cheap insurance. I have those along with a starter, which I have needed on the road. Jim k has the control board fairly cheap.
IMO the best "spares kit" to carry for the Onan consists of alligator-clip leads: two of them to be exact. One is to hook the coil's BAT terminal to the Battery+ and the other for momentarily hooking the Batt+ to the starter's low-current solenoid terminal when you want it to start. There's no reason to spend a C-note on a spare board until you really need one.
--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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