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Onan issue

JR
Jon Roche
Sun, Sep 5, 2021 9:45 PM

Generators and I do not get along.

Trying to help my friend ed with his onan.  This thing has been kicking our butts for a couple seasons as well as a couple others who have tried
helping.

Starts.  Runs for a while.  5 min?  Peters out.  Will start and repeat when it cools.

Has newer(last couple years we have been tossing parts at it).

Fuel pump(oem airtex style).
Fuel hose
Fuel shut off.

Have rebuilt multiple carbs.  This last carb came from jeff sirum-  rebuilt.

Harley coil.

We just put in bovee ignition.

Oil level full.  Lots of gas.

I am thinking we have a bad coil.  Spark seems maybe weak when it shuts down and kinda erratic.      Trying to watch it with a timing light.  Spark
never disappears but when it quits it will drop
To like 600 rpm for 20 seconds??  It  indicates spark,  but I think it should flash more.

Shooting starting fluid in to restart it does not seem to work.  And plugs are not really wet.

Short of dumping the carb bowl.  I am thinking it has gas.  Take hose off and there is gas to the carb.  Not vapor locked.  (Was thinking it was a
fuel issue,  but replaced all that!).

I am wondering what powers the coil???  I am thinking that maybe I need to get a different power source to it(hotwire).

Man it now runs nice when it runs!

Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/

Generators and I do not get along. Trying to help my friend ed with his onan. This thing has been kicking our butts for a couple seasons as well as a couple others who have tried helping. Starts. Runs for a while. 5 min? Peters out. Will start and repeat when it cools. Has newer(last couple years we have been tossing parts at it). Fuel pump(oem airtex style). Fuel hose Fuel shut off. Have rebuilt multiple carbs. This last carb came from jeff sirum- rebuilt. Harley coil. We just put in bovee ignition. Oil level full. Lots of gas. I am thinking we have a bad coil. Spark seems maybe weak when it shuts down and kinda erratic. Trying to watch it with a timing light. Spark never disappears but when it quits it will drop To like 600 rpm for 20 seconds?? It indicates spark, but I think it should flash more. Shooting starting fluid in to restart it does not seem to work. And plugs are not really wet. Short of dumping the carb bowl. I am thinking it has gas. Take hose off and there is gas to the carb. Not vapor locked. (Was thinking it was a fuel issue, but replaced all that!). I am wondering what powers the coil??? I am thinking that maybe I need to get a different power source to it(hotwire). Man it now runs nice when it runs! -- Jon Roche 75 palm beach EBL EFI, manny headers, Micro Level, rebuilt most of coach now. St. Cloud, MN http://lqqkatjon.blogspot.com/
JH
James Hupy
Sun, Sep 5, 2021 9:59 PM

Coil would be my first guess. Gets hot and quits. Cools off and runs for a
bit. If you have Bovee's ignition, you have eliminated the ignition points
and poor primary ignition circuit. You might check your primary ignition
source conductor and connectors. If they are loose, they will exhibit
similar symptoms. No run when hot. Just what I would check. Sounds like you
have fuel system covered. If you have a GM upfitted coach, be sure you have
3/4 of a tank of fuel in the rear tank. That Onan fuel pump pickup only
goes part way into the fuel supply so you cannot use the Onan and run
yourself out of gasoline.
Jim Hupy
Salem, Oregon

On Sun, Sep 5, 2021, 2:45 PM Jon Roche lqqkatjon@gmail.com wrote:

Generators and I do not get along.

Trying to help my friend ed with his onan.  This thing has been kicking
our butts for a couple seasons as well as a couple others who have tried
helping.

Starts.  Runs for a while.  5 min?  Peters out.  Will start and repeat
when it cools.

Has newer(last couple years we have been tossing parts at it).

Fuel pump(oem airtex style).
Fuel hose
Fuel shut off.

Have rebuilt multiple carbs.  This last carb came from jeff sirum-
rebuilt.

Harley coil.

We just put in bovee ignition.

Oil level full.  Lots of gas.

I am thinking we have a bad coil.  Spark seems maybe weak when it shuts
down and kinda erratic.      Trying to watch it with a timing light.  Spark
never disappears but when it quits it will drop
To like 600 rpm for 20 seconds??  It  indicates spark,  but I think it
should flash more.

Shooting starting fluid in to restart it does not seem to work.  And
plugs are not really wet.

Short of dumping the carb bowl.  I am thinking it has gas.  Take hose off
and there is gas to the carb.  Not vapor locked.  (Was thinking it was a
fuel issue,  but replaced all that!).

I am wondering what powers the coil???  I am thinking that maybe I need
to get a different power source to it(hotwire).

Man it now runs nice when it runs!

Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/


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Coil would be my first guess. Gets hot and quits. Cools off and runs for a bit. If you have Bovee's ignition, you have eliminated the ignition points and poor primary ignition circuit. You might check your primary ignition source conductor and connectors. If they are loose, they will exhibit similar symptoms. No run when hot. Just what I would check. Sounds like you have fuel system covered. If you have a GM upfitted coach, be sure you have 3/4 of a tank of fuel in the rear tank. That Onan fuel pump pickup only goes part way into the fuel supply so you cannot use the Onan and run yourself out of gasoline. Jim Hupy Salem, Oregon On Sun, Sep 5, 2021, 2:45 PM Jon Roche <lqqkatjon@gmail.com> wrote: > Generators and I do not get along. > > Trying to help my friend ed with his onan. This thing has been kicking > our butts for a couple seasons as well as a couple others who have tried > helping. > > Starts. Runs for a while. 5 min? Peters out. Will start and repeat > when it cools. > > Has newer(last couple years we have been tossing parts at it). > > Fuel pump(oem airtex style). > Fuel hose > Fuel shut off. > > Have rebuilt multiple carbs. This last carb came from jeff sirum- > rebuilt. > > Harley coil. > > We just put in bovee ignition. > > Oil level full. Lots of gas. > > I am thinking we have a bad coil. Spark seems maybe weak when it shuts > down and kinda erratic. Trying to watch it with a timing light. Spark > never disappears but when it quits it will drop > To like 600 rpm for 20 seconds?? It indicates spark, but I think it > should flash more. > > Shooting starting fluid in to restart it does not seem to work. And > plugs are not really wet. > > Short of dumping the carb bowl. I am thinking it has gas. Take hose off > and there is gas to the carb. Not vapor locked. (Was thinking it was a > fuel issue, but replaced all that!). > > I am wondering what powers the coil??? I am thinking that maybe I need > to get a different power source to it(hotwire). > > Man it now runs nice when it runs! > -- > Jon Roche > 75 palm beach > EBL EFI, manny headers, Micro Level, rebuilt most of coach now. > St. Cloud, MN > http://lqqkatjon.blogspot.com/ > _______________________________________________ > GMCnet mailing list > Unsubscribe or Change List Options: >
JR
John R. Lebetski
Sun, Sep 5, 2021 10:37 PM

Meter for 12 at coil/pump (same circuit). My guess is a bad solder on back side of board.  See if Voltage goes away or weak when it dies. Use clip
leads and meter or a small light bulb would be easy to watch. Betting on a bad solder ( dull ring of death) on back side of board.  Besides the
relays, the actual Faston tabs can have it as can fuse holder. Examine under magnifying light.
If this only happens when drawer closed, it’s pinched fuel line to tray barb.

John Lebetski
Woodstock, IL
77 Eleganza II

Meter for 12 at coil/pump (same circuit). My guess is a bad solder on back side of board. See if Voltage goes away or weak when it dies. Use clip leads and meter or a small light bulb would be easy to watch. Betting on a bad solder ( dull ring of death) on back side of board. Besides the relays, the actual Faston tabs can have it as can fuse holder. Examine under magnifying light. If this only happens when drawer closed, it’s pinched fuel line to tray barb. -- John Lebetski Woodstock, IL 77 Eleganza II
MC
Matt Colie
Sun, Sep 5, 2021 11:56 PM

Jon,

I do not know the Bovee ignition mod.  If it still has a condenser, change that out.  I have had several engines that had this condition and after I
changed everything else, I changed out that condenser (capacitor) and that fixed it.  On one of them, the change was accidental and it wasn't until
later that I figured out what fixed 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

Jon, I do not know the Bovee ignition mod. If it still has a condenser, change that out. I have had several engines that had this condition and after I changed everything else, I changed out that condenser (capacitor) and that fixed it. On one of them, the change was accidental and it wasn't until later that I figured out what fixed 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
BM
Billy Massey
Mon, Sep 6, 2021 12:48 AM

I concur.  Had that same situation with the Onan one time.
bdub

-----Original Message-----
If it still has a condenser, change that out.  I have had several engines that had this condition and after I
changed everything else, I changed out that condenser (capacitor) and that fixed it.

I concur. Had that same situation with the Onan one time. bdub -----Original Message----- If it still has a condenser, change that out. I have had several engines that had this condition and after I changed everything else, I changed out that condenser (capacitor) and that fixed it.
L
Larry
Mon, Sep 6, 2021 1:46 AM

Mine did that a long time ago. Found out that the fuel system (tanks and filler) were so tight that air had trouble getting in to replace used fuel,
and the Onan fuel pump was not strong enough to over come the relative vacuum created by the running engine.  Discovered the problem when I loosened
the gas cap and heard the woosh of air going into the tank. So, I loosed the gas cap and the Onan ran normally. JWID, so loosen the gas cap and try
running it for a while.

Larry
78 Royale w/500 Caddy
Menomonie, WI.

Mine did that a long time ago. Found out that the fuel system (tanks and filler) were so tight that air had trouble getting in to replace used fuel, and the Onan fuel pump was not strong enough to over come the relative vacuum created by the running engine. Discovered the problem when I loosened the gas cap and heard the woosh of air going into the tank. So, I loosed the gas cap and the Onan ran normally. JWID, so loosen the gas cap and try running it for a while. -- Larry 78 Royale w/500 Caddy Menomonie, WI.
JR
Jon Roche
Mon, Sep 6, 2021 1:52 AM

This is a friends coach that I help maintain.  I do not get enough time with it to really diagnose things properly.  He is retired so will swap out
and do many things so hard to chase down issues..  my onan is parted down now, so I took the bovee kit off mine and installed it on his.    I was not
really aware exacty what it was doing.  I thought the carb he got from sirum and a couple gmc’rs had it running well at last
Rally.  But it turns out they got it running good..

Adjusted the carb, generator, ect.    But it still had this shutdown issue.

Watching the voltage to the coil is what I should of done today.

Will see about that capacitor,  that should be easy too.

I thought it was a pinched fuel line.  But today I crossed that off.  Does same pushed in or pulled out and pulled out I can see fuel line is not
pinched. (Newer lines).

Thanks.

Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/

This is a friends coach that I help maintain. I do not get enough time with it to really diagnose things properly. He is retired so will swap out and do many things so hard to chase down issues.. my onan is parted down now, so I took the bovee kit off mine and installed it on his. I was not really aware exacty what it was doing. I thought the carb he got from sirum and a couple gmc’rs had it running well at last Rally. But it turns out they got it running good.. Adjusted the carb, generator, ect. But it still had this shutdown issue. Watching the voltage to the coil is what I should of done today. Will see about that capacitor, that should be easy too. I thought it was a pinched fuel line. But today I crossed that off. Does same pushed in or pulled out and pulled out I can see fuel line is not pinched. (Newer lines). Thanks. -- Jon Roche 75 palm beach EBL EFI, manny headers, Micro Level, rebuilt most of coach now. St. Cloud, MN http://lqqkatjon.blogspot.com/
CS
Carl Stouffer
Mon, Sep 6, 2021 2:36 AM

Jon,

Have you bypassed the board (jumper from 9 - 5)?  How about the LOP switch, if bad, that would shut the gen off after about 5 minutes?

Otherwise, John L may be on to something with the kinked fuel hose suggestion.

Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging.  GMCSJ and GMCMI member

Jon, Have you bypassed the board (jumper from 9 - 5)? How about the LOP switch, if bad, that would shut the gen off after about 5 minutes? Otherwise, John L may be on to something with the kinked fuel hose suggestion. -- Carl Stouffer '75 ex Palm Beach Tucson, AZ. Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
JR
Jon Roche
Tue, Sep 14, 2021 5:19 PM

the onan saga continues.

sucker still shuts down....  most parts new.  Our next thing is to try Another new coil,  and a new condenser on the coil.

we ran it off a small boat tank,  still quits after 5-10 minutes.  does that pulled out or pushed in.

jumpering the coil off the battery does not help.    also shows good voltage to the coil the entire time,  and the timing light seems to show spark,
but when it dies the rpm reduces and it kinda misses a little bit,  so the timing light flashes a little erratically, but I still think it has spark
to match?  we are trying new plugs,  need to get some new plug wires.    I just realized I was only testing the timing light flash on one side of
the coil, not the other....

the fuel shut off is new,  but also was not in the loop when we ran it on the boat tank.

been pretty busy,  so having a hard time really sitting down and thinking right on this.  I know people install a doorbell transformer when some
windings go bad??  does that effect how the engine runs,  like if those windings dump when it gets hot that would cause it to shut off?

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/

the onan saga continues. sucker still shuts down.... most parts new. Our next thing is to try Another new coil, and a new condenser on the coil. we ran it off a small boat tank, still quits after 5-10 minutes. does that pulled out or pushed in. jumpering the coil off the battery does not help. also shows good voltage to the coil the entire time, and the timing light seems to show spark, but when it dies the rpm reduces and it kinda misses a little bit, so the timing light flashes a little erratically, but I still think it has spark to match? we are trying new plugs, need to get some new plug wires. I just realized I was only testing the timing light flash on one side of the coil, not the other.... the fuel shut off is new, but also was not in the loop when we ran it on the boat tank. been pretty busy, so having a hard time really sitting down and thinking right on this. I know people install a doorbell transformer when some windings go bad?? does that effect how the engine runs, like if those windings dump when it gets hot that would cause it to shut off? -- Jon Roche 75 palm beach EBL EFI, manny headers, Micro Level, rebuilt most of coach now. St. Cloud, MN http://lqqkatjon.blogspot.com/
TS
Todd Sullivan
Tue, Sep 14, 2021 5:35 PM

I know you’ve been chasing this awhile over several threads. Did you ever
obtain Duane Simmons Onan troubleshooting chart? I don’t recall seeing that
you had gone through it in the thread(s)

Sully
Bellevue wa

On Tue, Sep 14, 2021 at 10:19 AM Jon Roche lqqkatjon@gmail.com wrote:

the onan saga continues.

sucker still shuts down....  most parts new.  Our next thing is to try
Another new coil,  and a new condenser on the coil.

we ran it off a small boat tank,  still quits after 5-10 minutes.  does
that pulled out or pushed in.

jumpering the coil off the battery does not help.    also shows good
voltage to the coil the entire time,  and the timing light seems to show
spark,
but when it dies the rpm reduces and it kinda misses a little bit,  so the
timing light flashes a little erratically, but I still think it has spark
to match?  we are trying new plugs,  need to get some new plug wires.
I just realized I was only testing the timing light flash on one side of
the coil, not the other....

the fuel shut off is new,  but also was not in the loop when we ran it on
the boat tank.

been pretty busy,  so having a hard time really sitting down and thinking
right on this.  I know people install a doorbell transformer when some
windings go bad??  does that effect how the engine runs,  like if those
windings dump when it gets hot that would cause it to shut off?

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/


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Unsubscribe or Change List Options:

I know you’ve been chasing this awhile over several threads. Did you ever obtain Duane Simmons Onan troubleshooting chart? I don’t recall seeing that you had gone through it in the thread(s) Sully Bellevue wa On Tue, Sep 14, 2021 at 10:19 AM Jon Roche <lqqkatjon@gmail.com> wrote: > the onan saga continues. > > sucker still shuts down.... most parts new. Our next thing is to try > Another new coil, and a new condenser on the coil. > > we ran it off a small boat tank, still quits after 5-10 minutes. does > that pulled out or pushed in. > > jumpering the coil off the battery does not help. also shows good > voltage to the coil the entire time, and the timing light seems to show > spark, > but when it dies the rpm reduces and it kinda misses a little bit, so the > timing light flashes a little erratically, but I still think it has spark > to match? we are trying new plugs, need to get some new plug wires. > I just realized I was only testing the timing light flash on one side of > the coil, not the other.... > > the fuel shut off is new, but also was not in the loop when we ran it on > the boat tank. > > been pretty busy, so having a hard time really sitting down and thinking > right on this. I know people install a doorbell transformer when some > windings go bad?? does that effect how the engine runs, like if those > windings dump when it gets hot that would cause it to shut off? > > > -- > Jon Roche > 75 palm beach > EBL EFI, manny headers, Micro Level, rebuilt most of coach now. > St. Cloud, MN > http://lqqkatjon.blogspot.com/ > _______________________________________________ > GMCnet mailing list > Unsubscribe or Change List Options: >