Onan not firing, but turns over great

L

luke walling

New member
Jul 5, 2017
27
0
0
Hi All,

I’ve begun working on the 78.

Now that I’ve replaced the 7 year old golf cart batteries I am starting to work on the electrics. The generator turns over smooth as silk and has what looks like fresh fluids in it. It doesn’t get fuel, and has a little aftermarket fuel shutoff valve inline. The prior owner reports it ran though I suspect this is 4-6 years ago.

I’ve friction fed it fuel, and it certainly feeds it in. But.. alas, no fire. Checked plugs (which don’t look too used, just a bit of carbon on their tips).

I do notice a module with wires removed that look to have been hooked up and leading back towards the ignition system and motherboard.

Any tips on if this could be the cause, where to start?

https://www.dropbox.com/s/x3w8xbhwkraz8mx/2017-10-15%2017.54.13.jpg?dl=0
 
Those wires by the heat sink (voltage reg) are disconnected because 78s do not have a lawn tractor battery. You crank off house bank and charge it via
125 AC to 12VDC converter. However you are missing one wire in that mess. There are supposed to he two wires on a faston twofer still connected and
taped up and a single wire taped up. Otherwise you won't have run voltage to the board. Untape those and show picture and look for one more
disconnected wire.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
> Hi All,
>
> I've begun working on the 78.
>
> Now that I've replaced the 7 year old golf cart batteries I am starting to work on the electrics. The generator turns over smooth as silk and has
> what looks like fresh fluids in it. It doesn't get fuel, and has a little aftermarket fuel shutoff valve inline. The prior owner reports it ran
> though I suspect this is 4-6 years ago.
>
> I've friction fed it fuel, and it certainly feeds it in. But.. alas, no fire. Checked plugs (which don't look too used, just a bit of carbon on
> their tips).
>
> I do notice a module with wires removed that look to have been hooked up and leading back towards the ignition system and motherboard.
>
> Any tips on if this could be the cause, where to start?

Luke,

The disconnected module is a charging voltage regulator that you do not need as the converter should be charging the house bank when the Onan is
running.

Did you do the jumper 5 to 9 and check for fuel delivery?
Also, the spark - at best - is barely visible in daylight. If it still has points, clean them.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
Try a little shot of starting fluid. If you have spark, it will start and run on it until it is used up. If it starts with the starting fluid, look
for the fuel problem. As Matt suggested, jumper pins 5 to 9 on the control board. You should hear the fuel pump run.
--
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
 
No fire ;(. I filled the bowl with fuel— plugs are soaked.

Will fiddle with the pump separately haven’t tested it alone yet as the fuel like is clear plastic and brittle, need to run all new stuff.

Thanks All

Try a little shot of starting fluid. If you have spark, it will start and run on it until it is used up. If it starts with the starting fluid, look
for the fuel problem. As Matt suggested, jumper pins 5 to 9 on the control board. You should hear the fuel pump run.
--
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

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Wet sparking plugs suggest no spark. Try the 5 - 9 jumper and see if it fires. If not, coil or wires or wiring error (Loose or broken). Check the
fuse on the control card. It's a 5 Amp, if it's blown determine why - usually a chafed or loose wire.

--johnny
--
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" - ol Andy, paraphrased
 
Clean the points. Check for fire by shorting them with a screwdriver when you are cleaning them.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.
 
Like Terry says. Long periods of inactivity on Onan engines will nearly
always result in some slight corrosion in the contact breakers. A points
file or in lieu of that a fingernail file, NOT AN EMERY BOARD OR SANDPAPER,
a few quick strokes through the closed points followed by a business card
to clean the residue should restore the points. A quick visual check to
verify that the points are actually opening, and you should at least have
spark. If that is not the case, save trouble down the road and install one
of Gary Bovee's electronic ignitions. Set it right, and forgetaboutit.
Jim Hupy
Salem, Or

Clean the points. Check for fire by shorting them with a screwdriver when
you are cleaning them.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.

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Just fired up the Onan! Still have to sort fuel line and pump issues, used gravity feed and a little external fuel.

The problems were easy - points were nice and new but corroded at the contacts, and ironically the fuse was good but the contacts on the board corroded too not allowing the circuit to close.

Cleaned up those things and she started right up and idled nice!

More to come as I try to figure out the fuel pump circuit problems.

Like Terry says. Long periods of inactivity on Onan engines will nearly
always result in some slight corrosion in the contact breakers. A points
file or in lieu of that a fingernail file, NOT AN EMERY BOARD OR SANDPAPER,
a few quick strokes through the closed points followed by a business card
to clean the residue should restore the points. A quick visual check to
verify that the points are actually opening, and you should at least have
spark. If that is not the case, save trouble down the road and install one
of Gary Bovee's electronic ignitions. Set it right, and forgetaboutit.
Jim Hupy
Salem, Or

Clean the points. Check for fire by shorting them with a screwdriver when
you are cleaning them.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.

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Luke, that Onan should not idle. It should run at the governed speed that
produces 50-60 hertz and around 124-130 volts AC at no load. Somewhere
around 1750 rpm. Might sound like idle speed compared to a Honda or other
late model generators. DO NOT REV IT UP BY PULLING ON THE GOVERNOR LINKAGE
WHILE UNDER LOAD, IT WILL FRY WHATEVER IS PLUGGED INTO IT.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> Just fired up the Onan! Still have to sort fuel line and pump issues,
> used gravity feed and a little external fuel.
>
> The problems were easy - points were nice and new but corroded at the
> contacts, and ironically the fuse was good but the contacts on the board
> corroded too not allowing the circuit to close.
>
> Cleaned up those things and she started right up and idled nice!
>
> More to come as I try to figure out the fuel pump circuit problems.
>
>
>
>
> On Mon, Oct 16, 2017 at 11:34 AM -0400, "James Hupy"
>
> Like Terry says. Long periods of inactivity on Onan engines will nearly
> always result in some slight corrosion in the contact breakers. A points
> file or in lieu of that a fingernail file, NOT AN EMERY BOARD OR SANDPAPER,
> a few quick strokes through the closed points followed by a business card
> to clean the residue should restore the points. A quick visual check to
> verify that the points are actually opening, and you should at least have
> spark. If that is not the case, save trouble down the road and install one
> of Gary Bovee's electronic ignitions. Set it right, and forgetaboutit.
> Jim Hupy
> Salem, Or
>

>
> Clean the points. Check for fire by shorting them with a screwdriver when
> you are cleaning them.
> --
> Terry Kelpien
>
> ASE Master Technician
>
> 73 Glacier 260
>
> Smithfield, Va.
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
> _______________________________________________
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> Unsubscribe or Change List Options:
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>
 
Probably a poor choice of words.

Don’t have the tools to tell the rpm, however, outlets inside giving 112-115 volts pretty consistently.

Luke

Luke, that Onan should not idle. It should run at the governed speed that
produces 50-60 hertz and around 124-130 volts AC at no load. Somewhere
around 1750 rpm. Might sound like idle speed compared to a Honda or other
late model generators. DO NOT REV IT UP BY PULLING ON THE GOVERNOR LINKAGE
WHILE UNDER LOAD, IT WILL FRY WHATEVER IS PLUGGED INTO IT.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> Just fired up the Onan! Still have to sort fuel line and pump issues,
> used gravity feed and a little external fuel.
>
> The problems were easy - points were nice and new but corroded at the
> contacts, and ironically the fuse was good but the contacts on the board
> corroded too not allowing the circuit to close.
>
> Cleaned up those things and she started right up and idled nice!
>
> More to come as I try to figure out the fuel pump circuit problems.
>
>
>
>

>
>
> Like Terry says. Long periods of inactivity on Onan engines will nearly
> always result in some slight corrosion in the contact breakers. A points
> file or in lieu of that a fingernail file, NOT AN EMERY BOARD OR SANDPAPER,
> a few quick strokes through the closed points followed by a business card
> to clean the residue should restore the points. A quick visual check to
> verify that the points are actually opening, and you should at least have
> spark. If that is not the case, save trouble down the road and install one
> of Gary Bovee's electronic ignitions. Set it right, and forgetaboutit.
> Jim Hupy
> Salem, Or
>

>
> Clean the points. Check for fire by shorting them with a screwdriver when
> you are cleaning them.
> --
> Terry Kelpien
>
> ASE Master Technician
>
> 73 Glacier 260
>
> Smithfield, Va.
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
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> Probably a poor choice of words.
>
> Don't have the tools to tell the rpm, however, outlets inside giving 112-115 volts pretty consistently.
>
> Luke

Luke,

I have no idea where you are located, but if it is near any civilization, go look for and get any version of a Kill-A-Watt. At most it will be 30$us.
It will tell you the output voltage and the frequency that the Onan is running. Carry that and enough extension cord so you can get it near the Onan
while you are adjusting it and you will never be out in the weeds.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
Any Harbor Freight carries the original Kill-A-Watt. It's $24.95 and if you have a 20% coupon , you get it for $19.95. I use it to adjust and
monitor my Onan for voltage and frequency.

Jerry
--
Jerry Sitzlar..... 77 Eleganza II, Twin bed, dry bath......
Lenoir City, TN
 
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