| Onan No Spark [message #280283] |
Fri, 19 June 2015 13:03  |
Justin Brady
Messages: 769
Registered: April 2015
Location: Bell Buckle, TN
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I've been playing with my Onan 6K a bit.
It was stuck so I pulled the head and pushed it free and cleaned it up, it looks to be in good shape inside.
Once I got it turning over i have found that I have no spark.
Breaker points seem to be working, didn't try to measure voltage there, what should it be?
I haven't been able to make any sense of the troubleshooting guides so I was hoping you guys have some suggestions for me to try?
Oil level is a bit low, would the oil sensor cut the spark?
Looking at the board, it seems to be in good shape, no blown resistors or caps etc.
Tried to measure resistance of the coil, and couldn't get anything but infinity. (put positive lead in the plug wire hole and put negative on the ground bolt on the top of the coil)
Any ideas?
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455
[Updated on: Fri, 19 June 2015 13:04] Report message to a moderator |
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| Re: Onan No Spark [message #280285 is a reply to message #280283] |
Fri, 19 June 2015 13:47  |
Dennis S
Messages: 3046
Registered: November 2005
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Here is an easy to read guide.
http://www.gmccoop.com/wake_up_your_onan.htm
Dennis
SONICJK wrote on Fri, 19 June 2015 13:03I've been playing with my Onan 6K a bit.
It was stuck so I pulled the head and pushed it free and cleaned it up, it looks to be in good shape inside.
Once I got it turning over i have found that I have no spark.
Breaker points seem to be working, didn't try to measure voltage there, what should it be?
I haven't been able to make any sense of the troubleshooting guides so I was hoping you guys have some suggestions for me to try?
Oil level is a bit low, would the oil sensor cut the spark?
Looking at the board, it seems to be in good shape, no blown resistors or caps etc.
Tried to measure resistance of the coil, and couldn't get anything but infinity. (put positive lead in the plug wire hole and put negative on the ground bolt on the top of the coil)
Any ideas?
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: Onan No Spark [message #280294 is a reply to message #280283] |
Fri, 19 June 2015 14:46 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Dennis -
To test the coil with an ohmmeter, measure from one spark plug connector to the other. The thing fires both plugs at ones in series. If you wish to test only one side, the other must be grounded. There aren't two coils in there, it's a 'wasted spark' system which fores both plugs at once. Since on cylinder will be on the exhaust stroke, that spark is wasted. JUmop the connectors as indicated in the test procedure, and you will eliminate the safety circuits entirely.
--johnny
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: Onan No Spark [message #280295 is a reply to message #280294] |
Fri, 19 June 2015 15:19 |
cbryan
Messages: 451
Registered: May 2012
Location: Ennis, Texas
Karma: 3
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Definitely add oil to the crankcase, I would think, because if it has run short of oil, it could be cycling on the oil pressure switch, and if you bypass that, you could be lunching the engine from lack of oil pressure. Then after it's running and you stop it, you can change it when it's hot provided it makes AC power and little oil smoke, no bad noises, and it seems worth the investment of the clean oil. People use a coozie to put around the filter to keep the cooling air inside the sheet metal, if the original gasket is missing which it often is. A coozie is one of those closed cell foam surrounds for a cold drink. Thanks I think to Matt Colie for that idea.
Best,
Carey
Carey from Ennis, Texas
78 Royale, 500 Cadillac, Rance Baxter EFI.
[Updated on: Fri, 19 June 2015 15:23] Report message to a moderator |
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| Re: Onan No Spark [message #280298 is a reply to message #280283] |
Fri, 19 June 2015 16:26 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Check both plugs for .020 gap and no junk in the gaps. The coil primary is like any old school ignition w points a condenser. Coil secondary is one end of coil to one plug and other to the other. The engine block is just a condutor between the two outer plug electrodes. Not negative to the coil as it us a balanced system. Be sure the wires are all the way onto the coil spike terminals.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Onan No Spark [message #280324 is a reply to message #280283] |
Sat, 20 June 2015 04:15 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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There is NO ground connection of the secondary side of the coil. Measure form one spark plug wire to the other. You will be reading hthe spark plug wire and the coil. Keep in mind that those are resistance wires. If that reading is open, then unplug the spark plug wire at the coil and read one high voltage port to the other one.
If you are looking for spark at one plug, the other plug MUST be installed and have the wire attached. The two plugs are wired in series so the opposite plug from the one you are testing must be installed and wired.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Onan No Spark [message #280491 is a reply to message #280324] |
Mon, 22 June 2015 12:50 |
Justin Brady
Messages: 769
Registered: April 2015
Location: Bell Buckle, TN
Karma: 11
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Thanks for the help guys.
I got the onan to fire and run.
First issue was the starter, the bendix gear doesn't always kick in. Lubed it up a bit and it works better. I'll pull it all the way down at some point.
When it does engage it sounds AWFUL, like a squealing pig...is this normal?
Once that worked I jumpered + to the coil and it fired up on a cup of gas, the fuel line to it gets no fuel, not sure why. Where does the Onan fuel line connect to the tanks? Do I have to drop them to get to it to replace?
It won't run without the jumper to + on the coil, so I will be removing the board and cleaning it and checking the relays. Anything in particular I should be looking for?
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455
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| Re: Onan No Spark [message #280514 is a reply to message #280491] |
Mon, 22 June 2015 17:15 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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SONICJK wrote on Mon, 22 June 2015 13:50Thanks for the help guys.
I got the onan to fire and run.
<snip>
1 - Once that worked I jumpered + to the coil and it fired up on a cup of gas, the fuel line to it gets no fuel, not sure why. Where does the Onan fuel line connect to the tanks? Do I have to drop them to get to it to replace?
2 - It won't run without the jumper to + on the coil, so I will be removing the board and cleaning it and checking the relays. Anything in particular I should be looking for?
Reply to:
1 - As you have a Palm Beach (why we like sigfiles), the fuel for the APu come from a dedicated connection on the outboard rear of the main (rear) tank. Some have reported being able to replace the 1/4 fuel line without dropping the tanks. More about this down the pages.
2 - There can be a number of reasons why it won't stay running without the jumper. One of them is the LOP (Low Oil Pressure) switch. Are you sure that there is adequate lube oil in the machine?. After that, go to http://www.gmcws.org/Tech/dsimmons/onan/onan.html and take advantage of what Duane Simmons put together with great detail. You do have the manuals- Right? If no, they can be downloaded at Bdub's page.
Good luck Guy - You'll get it
Matt
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: Onan No Spark [message #280578 is a reply to message #280514] |
Tue, 23 June 2015 14:07 |
Justin Brady
Messages: 769
Registered: April 2015
Location: Bell Buckle, TN
Karma: 11
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I topped off the oil tank so there should be plenty in there, I will however bypass it and see if perhaps it's faulty.
I appreciate all the help guys.
Any input on the noise at startup? Is the loud awful squeal normal?
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455
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| Re: [GMCnet] Onan No Spark [message #280584 is a reply to message #280578] |
Tue, 23 June 2015 18:04 |
Jim Miller
Messages: 501
Registered: March 2008
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On Jun 23, 2015, at 3:07 PM, Justin Brady wrote:
>
> Any input on the noise at startup? Is the loud awful squeal normal?
Of course it is not normal. Do you think GM would have tolerated a squealing genset in their MH that was very well engineered in every other way?
You probably have the flywheel rubbing the shroud or some other rotational interference issue going on. Maybe the armature tail bearing is defective?
--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] Onan No Spark [message #280735 is a reply to message #280584] |
Thu, 25 June 2015 22:02 |
Justin Brady
Messages: 769
Registered: April 2015
Location: Bell Buckle, TN
Karma: 11
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This thing is a bear!
New issue, had it running without the jumper and then it just died. Haven't been able to restart it since. No spark again!
After fiddling with it I have found that the only way I can get spark is by touching the top right relay on the control board. When I open and close the contacts I get a spark. Opening and closing the points does nothing.
Any ideas?
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455
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| Re: [GMCnet] Onan No Spark [message #280742 is a reply to message #280735] |
Thu, 25 June 2015 23:06 |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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SONICJK wrote on Thu, 25 June 2015 22:02This thing is a bear!
New issue, had it running without the jumper and then it just died. Haven't been able to restart it since. No spark again!
After fiddling with it I have found that the only way I can get spark is by touching the top right relay on the control board. When I open and close the contacts I get a spark. Opening and closing the points does nothing.
Any ideas? Here is everything I know about the Onan board. I plagiarized it from a GMC data store somewhere. Original credit goes to the late Duane Simmons.
Pins 1 to 6 have two pins each, one across the top to connect to the remote and another down lower, mixed in with the rest of the stuff.
Pin 1 is ground for the board. it is also connected to the remote, providing a ground to the remote switch.
Pin 2 is the input to the board for the remote stop function. Grounding this pin cause the board to shut off the generator.
Pin 3 is the input to the board for the remote start function. Grounding this pin cause the board to start the generator.
Pin 4 doesn't seem to be used in our application. Looks like another input into the same circuits that the oil pressure switch connect to.
Pin 5 is FUSED 12 volts from the battery.
Pin 6 has 12volts (fused) only when the generator is running.
Pin 7 is the ground side of the coil of the start solenoid. Grounding this point should cause the starter to engage.
Pin 8 is an A/C "generator running" input to the board from the flywheel alternator. (The other side of this AC signal is pin 5.) It disengages the starter and "latches" the voltage provided to pin 9.
Pin 9 is the output of the board to BOTH the ignition and the fuel pump. If there is voltage here, the pump should be running and the points/coil should have power.
Pin 10 has 12volts from the starter solenoid when the starter is engaged. It provides power to pin 9 when starting.
Pin 11 is UN-FUSED 12 volts from the battery.
Pin 12 is the input of the board from the oil pressure switch. The switch applies a ground when there isn't oil pressure. Just disconnecting this pin disables the function.
NOW for the methods of jumping (bypassing):
The main differences in jumping is where the power comes from, all of them connect to pin 9 (electrically the same point as the + side of the coil, the fuel pump and the fuel shut-off solenoid):
Method 1.) Some jump from pin 11 but it is better to use fused power on pin 5. If pin 11 works but pin 5 does not, look at the fuse.
Method 2.) The most popular spot is pin 5. You still use the button on the board to get the starter to turn. But you need to un-jumper the pins to turn off the generator.
Method 3.) Relatively unknown method is pin 6. This disables the generator running and low oil pressure functions but maintains BOTH the start AND STOP functions of the board. As the lower pin 6 is right next to pin 9, a short one inch jumper can be left in place with the cover on and genset pushed back in the "Onan-hole." Be aware that if you try to start the generator but it doesn't start, there will still be power to the pump and ignition until you press "stop." While all methods keep the power on pin 9, it is just easier to forget without a wire hanging off the generator.
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| Re: [GMCnet] Onan No Spark [message #280753 is a reply to message #280735] |
Fri, 26 June 2015 04:26 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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The upper right relay is K2. I assume that you have a wiring diagram for the board. K2 is energized by the alternator behind the flywheel which supplies around 30 VAC on pins 5 and 8. jumper pins 5 to 9 to get it running and then measure 5 to 8 looking for around 30 volts AC.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Onan No Spark [message #280764 is a reply to message #280283] |
Fri, 26 June 2015 08:40 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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The biggest failure of these old boards is poor connection either due to corrosion on the connectors or cracks on the board runs/connectors. Second is the electrolytic capacitors. Third is the diodes. If yours has the original glass case diodes, replace them and replace the two electrolytics while you're at it. Examine all the printed wiring and especially the blade connectors on the wiring side with a magnifying glass, looking for cracks. Apply 12 volts (I use a wallwart) DC to each relay coil directly and note that the relay pulls in. If the board passes these tests it is likely working and the trouble is likely someplace else. You can replace every component on the board except the relays for less than 20 scoots. A couple - particularly the UJT - are hard to find but seldom fail.
--johnny
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: Onan No Spark [message #280768 is a reply to message #280764] |
Fri, 26 June 2015 09:10 |
Justin Brady
Messages: 769
Registered: April 2015
Location: Bell Buckle, TN
Karma: 11
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I may just do that Johnny, I'm about tired of messing with it.
After looking for quite some time at the schematics, I can't seem to figure out how my k2 relay is causing the system to spark.
No matter what i jumper i get no spark. Until I manually touch the K2 relay, then it sparks one time.
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455
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| Re: [GMCnet] Onan No Spark [message #280769 is a reply to message #280768] |
Fri, 26 June 2015 09:19 |
James Hupy
Messages: 6806
Registered: May 2010
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Just as a point of information, perhaps to aid you a bit in diagnosis,
points type ignitions make spark when the primary side opens, not closes.
So if that relay has current applied to it continously and you tap or thump
it and it breaks the primary circuit momentarily, you will see a spark on
the secondary side of the coil. Sounds like either a bad relay or poor
connections to or around it.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Jun 26, 2015 7:10 AM, "Justin Brady" wrote:
> I may just do that Johnny, I'm about tired of messing with it.
>
> After looking for quite some time at the schematics, I can't seem to
> figure out how my k2 relay is causing the system to spark.
> No matter what i jumper i get no spark. Until I manually touch the K2
> relay, then it sparks one time.
> --
> 1976 Palm Beach 455
> _______________________________________________
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| Re: [GMCnet] Onan No Spark [message #280776 is a reply to message #280769] |
Fri, 26 June 2015 11:35 |
Justin Brady
Messages: 769
Registered: April 2015
Location: Bell Buckle, TN
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Thanks Jim that's helpful.
The thing that's getting me is that the points are opening and closing with power to the coil and I'm still getting no spark.
Perhaps this points to the condensor?
If you guys get tired of questions feel free to stop answering! I just find when I can't figure something out, asking for help from the people that know is a more effective solution than continuing to screw with something until I break it
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455
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| Re: Onan No Spark [message #280779 is a reply to message #280768] |
Fri, 26 June 2015 12:28 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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K2 is the "up to speed relay" it is energized by the 30 VAC from the alternator to tell the board that the generator / engine is running. K2 then picks up K3 which supplies +12 power to the coil. K2 is not involved when the engine is cranking. It only get involved after the engine starts running.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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