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Onan troubleshoot [message #368803] Thu, 17 February 2022 10:59 Go to next message
Ken Shaffer is currently offline  Ken Shaffer   United States
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Location: Marion Iowa
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can anyone help me with my Onan 6k? It ran perfectly 2 years ago. It slowly starting running rough. Now it will start and run on a low RPM for maybe 5 minutes. After that it becomes really rough and eventually quits. I have done the following and nothing has changed. It still acts the same as it did.

replaced spark plugs, fuel pump, converted to Bovee's electronic ignition, rebuilt carburetor. I had previously installed Dinosaur board.
I notice that the front cylinder seems to have a stronger spark than the rear.
My next plan is to change plug wires and coil.
I am running out of ideas. (and new parts to throw at it)
Has anyone had a similar problem and can share your experience with me?


Ken Shaffer Marion Iowa 73 Canyon Lands, 455, Micro-level, Alum radiator, Alcoa wheels, Lenzi hubs/bearings, Howell EFI/EBL, Rostra Cruise, Custom interior
[GMCnet] Re: Onan troubleshoot [message #368805 is a reply to message #368803] Thu, 17 February 2022 11:15 Go to previous messageGo to next message
k2gkk is currently offline  k2gkk   United States
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Pinched/collapsed fuel line? zPull drawer out and see if problem continues.

Mac in OKC, OK

Sent from my iPhone

On Feb 17, 2022, at 10:59, Ken Shaffer wrote:

can anyone help me with my Onan 6k? It ran perfectly 2 years ago. It slowly starting running rough. Now it will start and run on a low RPM for
maybe 5 minutes. After that it becomes really rough and eventually quits. I have done the following and nothing has changed. It still acts the same
as it did.

replaced spark plugs, fuel pump, converted to Bovee's electronic ignition, rebuilt carburetor. I had previously installed Dinosaur board.
I notice that the front cylinder seems to have a stronger spark than the rear.
My next plan is to change plug wires and coil.
I am running out of ideas. (and new parts to throw at it)
Has anyone had a similar problem and can share your experience with me?

--
Ken Shaffer
Marion Iowa
73 Canyon Lands, 455, Micro-level, Alum radiator, Alcoa wheels, Lenzi hubs/bearings, Howell EFI/EBL, Rostra Cruise, Custom interior
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[GMCnet] Re: Onan troubleshoot [message #368806 is a reply to message #368803] Thu, 17 February 2022 11:12 Go to previous messageGo to next message
sgltrac is currently offline  sgltrac   United States
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Registered: April 2011
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Ken,

You need Duane Simmons' onan troubleshooting guide. Someone more web savvy
here should post a link for you soon.

Have you tried running the genny with a temporary gravity feed fuel tank in
order to rule out fuel delivery?

Sully
Bellevue wa

On Thu, Feb 17, 2022 at 8:59 AM Ken Shaffer wrote:

> can anyone help me with my Onan 6k? It ran perfectly 2 years ago. It
> slowly starting running rough. Now it will start and run on a low RPM for
> maybe 5 minutes. After that it becomes really rough and eventually
> quits. I have done the following and nothing has changed. It still acts
> the same
> as it did.
>
> replaced spark plugs, fuel pump, converted to Bovee's electronic ignition,
> rebuilt carburetor. I had previously installed Dinosaur board.
> I notice that the front cylinder seems to have a stronger spark than the
> rear.
> My next plan is to change plug wires and coil.
> I am running out of ideas. (and new parts to throw at it)
> Has anyone had a similar problem and can share your experience with me?
>
> --
> Ken Shaffer
> Marion Iowa
> 73 Canyon Lands, 455, Micro-level, Alum radiator, Alcoa wheels, Lenzi
> hubs/bearings, Howell EFI/EBL, Rostra Cruise, Custom interior
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
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Sully 77 Royale basket case. Future motorhome land speed record holder(bucket list) Seattle, Wa.
[GMCnet] Re: Onan troubleshoot [message #368807 is a reply to message #368805] Thu, 17 February 2022 11:38 Go to previous messageGo to next message
Ken Shaffer is currently offline  Ken Shaffer   United States
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Registered: September 2017
Location: Marion Iowa
Karma: -1
Member
I did replace the fuel pump but I did not pull out of a separate tank. I
will try that to make sure the fuel line is not pinched between pump and
fuel tank. Good idea, thanks!



On Thu, Feb 17, 2022 at 11:15 AM K2GKK D C_Mac_ Macdonald
wrote:

> Pinched/collapsed fuel line? zPull drawer out and see if problem
> continues.
>
> Mac in OKC, OK
>
> Sent from my iPhone
>
> On Feb 17, 2022, at 10:59, Ken Shaffer wrote:
>
> can anyone help me with my Onan 6k? It ran perfectly 2 years ago. It
> slowly starting running rough. Now it will start and run on a low RPM for
> maybe 5 minutes. After that it becomes really rough and eventually
> quits. I have done the following and nothing has changed. It still acts
> the same
> as it did.
>
> replaced spark plugs, fuel pump, converted to Bovee's electronic ignition,
> rebuilt carburetor. I had previously installed Dinosaur board.
> I notice that the front cylinder seems to have a stronger spark than the
> rear.
> My next plan is to change plug wires and coil.
> I am running out of ideas. (and new parts to throw at it)
> Has anyone had a similar problem and can share your experience with me?
>
> --
> Ken Shaffer
> Marion Iowa
> 73 Canyon Lands, 455, Micro-level, Alum radiator, Alcoa wheels, Lenzi
> hubs/bearings, Howell EFI/EBL, Rostra Cruise, Custom interior
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:


Ken Shaffer Marion Iowa 73 Canyon Lands, 455, Micro-level, Alum radiator, Alcoa wheels, Lenzi hubs/bearings, Howell EFI/EBL, Rostra Cruise, Custom interior
Re: Onan troubleshoot [message #368808 is a reply to message #368803] Thu, 17 February 2022 14:17 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
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Ken,

<https://gmcidiotsguide.com/chapter-5> give you access to all kinds of stuff.

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
Re: Onan troubleshoot [message #368809 is a reply to message #368803] Thu, 17 February 2022 14:34 Go to previous messageGo to next message
Russell K. is currently offline  Russell K.   United States
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Hi Ken,
This video has some great onan info. It helped me.

https://youtu.be/nnns9GKPw6g

Russell


1978 Eleganza II, Dunedin, Florida
Re: Onan troubleshoot [message #368810 is a reply to message #368803] Thu, 17 February 2022 15:24 Go to previous messageGo to next message
boybach is currently offline  boybach   
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Location: Vancouver Island
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Senior Member
How much gas have you got in the Motorhome? The genny will quit long before you run out of gas.

Larry


Larry - Victoria BC - 1977 ex-Palm Beach "Ol' Leaky" 40,000 miles, PO said everything working but forgot the word NOT. Atwood helium fridge, water heater & furnace. SS exhaust system, Onan, Iota Converter, R134A, New fuel lines & heat exchange hoses
Re: Onan troubleshoot [message #368812 is a reply to message #368803] Thu, 17 February 2022 17:00 Go to previous messageGo to next message
Larry is currently offline  Larry   United States
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Take the gas filler cap off. See if that does it. My fuel tank system was so tight that after 5 min or so of running, the Onan fuel pump was unable to overcome the vacuum created in the tank as fuel was drawn out an air was not allowed to replace consumed fuel. I drilled the cap to see it that would cure the issue and when it did, I put on a different fuel cap. No problems since.

Larry Smile
78 Royale w/500 Caddy
Menomonie, WI.
Re: Onan troubleshoot [message #368814 is a reply to message #368803] Thu, 17 February 2022 21:22 Go to previous messageGo to next message
JohnL455 is currently offline  JohnL455   United States
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“One plug having a better spark than other” is a red flag. The plugs are in series since waste spark ign so they should be the same. It goes coil tower-wire- plug-block-other plug-other wire-other coil terminal for each spark event. Check both plug gaps at .020. Then on bench meter them. Be sure no reading from terminal to body. Then check series resistance terminal to center electrode. Both plugs should have a similar internal resistor value. Plug QC isn’t what it used to be and I now precheck all before install. If there is any resistance value terminal to body the spark energy with go though that route instead of air gap as takes easier path. The other plug would have a better spark as the shunted one would behave as a pass through.

John Lebetski
Woodstock, IL
77 Eleganza II
Re: Onan troubleshoot [message #368815 is a reply to message #368803] Thu, 17 February 2022 22:56 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
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Decarbonize the heads / cylinders. It is suppose to be done every 200 hours.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: Onan troubleshoot [message #368817 is a reply to message #368814] Fri, 18 February 2022 06:54 Go to previous messageGo to next message
Jim Miller is currently offline  Jim Miller   United States
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JohnL455 wrote on Thu, 17 February 2022 22:22
“One plug having a better spark than other” is a red flag. The plugs are in series since waste spark ign so they should be the same..
I will point out that it is entirely likely to see a difference between the plugs from a wear perspective. The discharge energy from the coil is DC - and the plugs are in series as John pointed out - therefore one plug always fires electrode positive and other always fires electrode negative. This results in a different amount of heat generated across each gap and thus a differing level of arc erosion over time - the plug in one cylinder will always be producing a "hotter" spark than the plug in the other cylinder. An analogy is from welding where you will get significantly different electrode heating from running DCEP versus DCEN.

As for one plug having a "better spark than the other"....I don't see how you can determine that with an ionization-type spark tester on a wasted spark system.

If it were me I'd be ruling out fuel problems before going after ignition issues based on the original problem description...but hey, what do I know...
--Jim N8ECI


Jim Miller 1977 Eleganza II 1977 Royale Hamilton, OH
Re: Onan troubleshoot [message #368820 is a reply to message #368803] Fri, 18 February 2022 08:54 Go to previous messageGo to next message
JohnL455 is currently offline  JohnL455   United States
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Great insight Jim. Makes sense. Wanted to be sure he understood the system, and check plugs and gaps as no cost quick thing to rule out. To take it further to rule out the plugs after the Ohm test and gap check, swap their positions and sparks should appear same in that position for as much as you can tell.
My experience with poor off shore Champion plugs was this. My high mile Jeep would occasionally cold start with one dead cyl, then clear with a rev. It was also always slightly low on coolant. Logic pointed to a head gasket, Finally it got bad enough to set a cyl 2 misfire and pulling the 1 year old plugs found cyl 2 to have an internal short not visible to the eye. The low coolant was a bad cap (recently replaced but defective). So don’t assume recently replaced parts are good. Been 6 months and no misfires. There is a pretty inconsistent internal resistor variance plug to plug on brand new plugs. Copper plugs are cheap, so ones that are way off scale don’t get installed by me. Normal wide variance of say 20% gets a pass.


John Lebetski
Woodstock, IL
77 Eleganza II
Re: Onan troubleshoot [message #368826 is a reply to message #368820] Fri, 18 February 2022 12:43 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
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To reinforce Jim Miller's comment. I always swap the plug positions if I ever have plugs both out at the same time. I do this even if the Onan is running fine. I also check the gaps and make sure that they are exactly the same and correct. This series wired wasted spark system used on 2 cylinder engines can produce some interesting failures that you would not see on other systems.

De-carbonize the heads / cylinders.


Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: Onan troubleshoot [message #368829 is a reply to message #368826] Fri, 18 February 2022 16:36 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
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Ken Burton wrote on Fri, 18 February 2022 13:43
To reinforce Jim Miller's comment. I always swap the plug positions if I ever have plugs both out at the same time. I do this even if the Onan is running fine. I also check the gaps and make sure that they are exactly the same and correct. This series wired wasted spark system used on 2 cylinder engines can produce some interesting failures that you would not see on other systems.

De-carbonize the heads / cylinders.
Ken,

There is a new problem here...
I asked Mary to get me some oven cleaner.
She couldn't buy any. Everybody has self cleaning ovens.

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
Re: Onan troubleshoot [message #368830 is a reply to message #368803] Fri, 18 February 2022 18:05 Go to previous messageGo to next message
JohnL455 is currently offline  JohnL455   United States
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The appliance repair tech once said not to use the self cleaning feature if you want your equip to last. I’m going to try some John Deere foaming glass cleaner and see how that does.
On the Onan carb, did you ((breaker off) hold the throttle closed down to abot 500 RPM and adjust the idle mixture screw to best idle speed holding throttle closed? Then release throttle and set main jet no load and load? Rmember these are garden tractor engines (JD318) and were meant to throttle from idle to 3600 run speed. Ours are stuck at 1800 which in my opinion uses both carb circuits to some degree especially no load.


John Lebetski
Woodstock, IL
77 Eleganza II

[Updated on: Fri, 18 February 2022 18:08]

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[GMCnet] Re: Onan troubleshoot [message #368831 is a reply to message #368830] Fri, 18 February 2022 18:15 Go to previous messageGo to next message
James Hupy is currently offline  James Hupy   United States
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If you do the idle adjust bit, be darned sure that your generator is NOT
SUPPLYING POWER AT THIS TIME! What ever you might be powering at the time
ain't gonna like it, even a little bit. But, if you look at the throttle
position when the engine is cranking, you will notice that it is wide open,
not at idle. The governor spring is holding the throttle wide open until
the effort from the governor arm balances the effort of the spring. Jus'
sayin'..
Jim Hupy
Salem, Oregon

On Fri, Feb 18, 2022, 4:06 PM John R. Lebetski
wrote:

> The appliance repair tech once said not to use the self cleaning feature
> if you want you equip to last. I’m going to try some John Deere foaming
> glass cleaner and see how that does.
> On the Onan carb, did you ((breaker off) hold the throttle closed down to
> abot 500 RPM and adjust the idle mixture screw to best idle speed holding
> throttle closed? Then release throttle and set main jet no load and
> load? Rmember these are garden tractor engines (JD328) and were meant to
> throttle from idle to 3600 run speed. Ours are stick at 1800 which in my
> opinion uses both carb circuits to some degree especially no load.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
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Re: Onan troubleshoot [message #368834 is a reply to message #368803] Sat, 19 February 2022 08:35 Go to previous messageGo to next message
JohnL455 is currently offline  JohnL455   United States
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Yes Jim, breaker OFF was in my procedure.

John Lebetski
Woodstock, IL
77 Eleganza II
[GMCnet] Re: Onan troubleshoot [message #368838 is a reply to message #368834] Sat, 19 February 2022 11:21 Go to previous messageGo to next message
jimk is currently offline  jimk   United States
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Keep in mind that the gap on thes units are only .020, not .35.
Realize your using the Pertronic kit, which can handle .35.
Also the Ignition wire on the original need to be changed after 45 years.

On Sat, Feb 19, 2022 at 6:36 AM John R. Lebetski
wrote:

> Yes Jim, breaker OFF was in my procedure.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
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--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
Re: Onan troubleshoot [message #368850 is a reply to message #368829] Sun, 20 February 2022 01:36 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
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Walmart shows 6 different brands in stock. I have ever used over cleaner. I simply stick them in a bead blaster and hit them lightly. On the cylinder side I raise the piston to TDC and use a brass brush. I never looked for the proper procedure. All know is it sure runs better after cleaning.

https://www.walmart.com/search?q=oven%20cleaner&typeahead=oven%20cleaner


Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: Onan troubleshoot [message #368900 is a reply to message #368803] Fri, 25 February 2022 18:04 Go to previous messageGo to previous message
jhbridges is currently offline  jhbridges   United States
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I'd pay attention to Jim Miller if I were you. To my limited experience you describe a fuel problem.

--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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