ONAN Generator

With the makeup of todays gasolines you should only use a hose that is rated for this fuel as Jim has said. I only use a R14 rated fuel hose. Granted it cost more, but in the end it will out last any other hose on the market. These are all barricade Nitrile rubber hoses.

What is barricade Fuel Line hose:

https://images.oreillyauto.com/parts/img/documents/gat/gatesbarricade2page.pdf
and
https://images.oreillyauto.com/parts/img/documents/gat/gatesbarricade4page.pdf

Available sizes that we use on our coaches.

1/4” - https://www.oreillyauto.com/detail/b/barricade-3759/belts-hoses-16454/hoses-25069/bulk-hose-16664/bulk-hose---fuel-hose-18164/0a74c36f4425/gates-barricade-1-4-inch-i-d-nitrile-rubber-nbr-hose/27313/4349937?q=27313&pos=0

5/16” - https://www.oreillyauto.com/detail/b/barricade-3759/belts-hoses-16454/hoses-25069/crankcase-breather-hose-14015/df8b1723839a/gates-barricade-5-16-inch-i-d-nitrile-rubber-nbr-hose/27314/4349938?q=27314&pos=0

3/8” - https://www.oreillyauto.com/detail/b/barricade-3759/belts-hoses-16454/hoses-25069/bulk-hose-16664/bulk-hose---fuel-hose-18164/0a74c36f4425/gates-barricade-3-8-inch-i-d-nitrile-rubber-nbr-hose/27315/4349939?q=27315&pos=0

1/2” - https://www.oreillyauto.com/detail/b/barricade-3759/belts-hoses-16454/hoses-25069/bulk-hose-16664/bulk-hose---fuel-hose-18164/0a74c36f4425/gates-barricade-1-2-inch-i-d-nitrile-rubber-nbr-hose/27316/4349940?q=27316&pos=0

You can find other brands out there, but IMHO this is the best!

Information for your needs.

J.R. Wright
GMC Great Laker MHC
GMCGL Tech Editor
GMC Eastern States Charter Member
GMCMI
78 GMC Buskirk 29.5’ Stretch
75 GMC Avion (Under Reconstruction)
Michigan

>
> Get rid of that clear fuel line, and replace it with Gates Barricade Hose
> rated for fuel with alcohol in it. Nothing else.
> Jim Hupy
> Salem, Oregon
>
> On Thu, Jul 16, 2020, 9:18 AM Bob Dunahugh via Gmclist <

>
>> I've never seen a clear gas line to the Onan. Or any other location in a
>> GMC. Some clears are rated for gas. Some are not. I'd get it out if it was
>> mine. For me. I have to see ( gas) printed on the outside of any hose that
>> I'd install. As a gas line. It's my Comfort Zone thing.
>> Bob Dunahugh
>> _______________________________________________
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I can think of nothing in the Molex or control card that would affect only one cylinder. Your description of a 'hot' side makes me think one cylinder
is running lean. how that happens is strange, but mine once started that way - one cylinder firing, the other sputtering. Pulling and releasing the
choke rod fixed it, I never figured out what caused it. A compression check is in order though. I take it all the covers and seals including the oil
filter seal are in place.

--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
 
Rebuilt carb and put a new fuel line on. Put a set points and condenser in.
Right spark plug does not appear to be getting any spark. Left plug is getting hot to the touch, while right plug is not.
Engine ran fine until I noticed old fuel line and bowl gasket leaking and did the mentioned work to it.
--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach
 
Plug wire?
Jim Hupy
Salem, Oregon

On Fri, Aug 14, 2020, 4:36 PM Samuel Ferguson via Gmclist <

> Rebuilt carb and put a new fuel line on. Put a set points and condenser in.
> Right spark plug does not appear to be getting any spark. Left plug is
> getting hot to the touch, while right plug is not.
> Engine ran fine until I noticed old fuel line and bowl gasket leaking and
> did the mentioned work to it.
> --
> Samuel Ferguson
> Pittsfield, Illinois
> (West Central Illinois)
> 1976 GMC Palm Beach
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Steve,

The Onan's ignition system is known as a "lost spark" system. That means
that BOTH plugs fire at the same time -- always. They can't do otherwise
because they're connected to each end of a single secondary winding in the
ignition coil. The principle is that one of the pistons will be on the
compression stroke while the other is on the exhaust stroke. That is,
there will be ignition at the end-of-compression/beginning-of-power, but
not at the end-of-exhaust/beginning-of-intake phases.

So, what you need to do first is determine why the cold plug is cold. Pull
that plug, re-connect its plug wire, and ground it to the block. When you
hit the starter, there should be arcing between the plug's points. If
there's not, that plug wire is being shorted to the block somewhere between
the plug and the coil (or, very unlikely, the coils' suddenly shorted
internally). You'll have to find and correct that short to let the voltage
that IS reaching the other plug reach the cold one also.

If there is spark at the plug (as I expect), then you obviously have
another problem -- possibly fuel delivery to that cylinder. At least
you've eliminated the ignition system as a problem.

HTH,

Ken H.

On Fri, Aug 14, 2020 at 7:36 PM Samuel Ferguson via Gmclist <

> Rebuilt carb and put a new fuel line on. Put a set points and condenser in.
> Right spark plug does not appear to be getting any spark. Left plug is
> getting hot to the touch, while right plug is not.
> Engine ran fine until I noticed old fuel line and bowl gasket leaking and
> did the mentioned work to it.
> --
> Samuel Ferguson
> Pittsfield, Illinois
> (West Central Illinois)
> 1976 GMC Palm Beach
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Another way to think of it is the plugs are in series with the block serving to connect the two. If you disconnect one you get nothing. And yes the
electricity flows from center to side on one and side to center on the other.

--
John Lebetski
Woodstock, IL
77 Eleganza II
 
As Colonel Ken stated, in a "wasted spark" system it is almost impossible to fire one plug without the other one firing too because the two are in
series. One exception would be if one plug wire was shorted to ground or if the non firing plug is internally shorted. We see the second scenario
frequently on low compression airplane engines due to lead build up from using 100 octane fuel in 80-87 octane engines. Cleaning the plug(s) and
picking the lead out with a small pick fixes the problem.

You will not see lead in car engines because they have not sold leaded auto gas in many years. An excess of carbon and an oil or soot can foul a plug
and cause the same problem as lead. So clean and recheck the gap on the plug that is not firing. Also verify that the plug wire is not routed is
such a way that is could short to ground.

Also so do not check one plug for spark with the other one removed, or the other spark wire not connected to the coil and plug.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Ken,
I believe that this is a parallel system as the current goes thru each plug and then to ground and not one plug and then the other plug and ground. I remember working on series, parallel and series parallel diagrams for my one electronics class, if wrong I need to know why.

JR

>
> As Colonel Ken stated, in a "wasted spark" system it is almost impossible to fire one plug without the other one firing too because the two are in
> series. One exception would be if one plug wire was shorted to ground or if the non firing plug is internally shorted. We see the second scenario
> frequently on low compression airplane engines due to lead build up from using 100 octane fuel in 80-87 octane engines. Cleaning the plug(s) and
> picking the lead out with a small pick fixes the problem.
>
> You will not see lead in car engines because they have not sold leaded auto gas in many years. An excess of carbon and an oil or soot can foul a plug
> and cause the same problem as lead. So clean and recheck the gap on the plug that is not firing. Also verify that the plug wire is not routed is
> such a way that is could short to ground.
>
> Also so do not check one plug for spark with the other one removed, or the other spark wire not connected to the coil and plug.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
If you look at the ONAN coil, it is technically a step up transformer. One
large diameter sized wire that carries the primary current from B+ to
ground. As the current passes through the windings it creates a very strong
magnetic field, the lines of which also cut through the thousands of turns
of the secondary coil windings, "INDUCING" a high voltage/low amperage
electron flow in the secondary windings. The ignition points/condenser team
up to turn the primary current on and off when the points open and close.
This collapsing magnetic field produces a very high voltage/short duration
current flow that goes to ground through the plug wires and plugs, arcing
across the plug electrodes on their way to ground. This arcing ignites the
air/fuel mixture in the cylinder if it is present. If no fuel/air mix is
present, then that spark is "wasted". That is why the ONAN ignition system
is called a "waste spark" ignition system. Clear as mud, right?
Jim Hupy
Salem, Oregon

On Sun, Aug 16, 2020, 8:23 AM John Wright via Gmclist <

> Ken,
> I believe that this is a parallel system as the current goes thru each
> plug and then to ground and not one plug and then the other plug and
> ground. I remember working on series, parallel and series parallel
> diagrams for my one electronics class, if wrong I need to know why.
>
> JR
> > On Aug 15, 2020, at 2:12 AM, Ken Burton via Gmclist <

> >
> > As Colonel Ken stated, in a "wasted spark" system it is almost
> impossible to fire one plug without the other one firing too because the
> two are in
> > series. One exception would be if one plug wire was shorted to ground
> or if the non firing plug is internally shorted. We see the second scenario
> > frequently on low compression airplane engines due to lead build up from
> using 100 octane fuel in 80-87 octane engines. Cleaning the plug(s) and
> > picking the lead out with a small pick fixes the problem.
> >
> > You will not see lead in car engines because they have not sold leaded
> auto gas in many years. An excess of carbon and an oil or soot can foul a
> plug
> > and cause the same problem as lead. So clean and recheck the gap on the
> plug that is not firing. Also verify that the plug wire is not routed is
> > such a way that is could short to ground.
> >
> > Also so do not check one plug for spark with the other one removed, or
> the other spark wire not connected to the coil and plug.
> > --
> > Ken Burton - N9KB
> > 76 Palm Beach
> > Hebron, Indiana
> >
> > _______________________________________________
> > 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
>
 
> Ken,
> I believe that this is a parallel system as the current goes thru each plug and then to ground and not one plug and then the other plug and
> ground. I remember working on series, parallel and series parallel diagrams for my one electronics class, if wrong I need to know why.
>
> JR

JR,

I think you misunderstood what KenB was saying.

Spark plugs cannot be in parallel as typically defined because only one plug will fire. They cannot be in series as usually defined because the base
of the plug would have to be insulated at plug firing potential and this would be difficult. There are some gas turbines that do this for the
igniters, but you don't want to know what those cost.

The Onan like so many other engines with a double ended coil have a secondary winding that has no grounded end. There is a spark plug at each end, so
spark goes both ways. Ego, if one plug fires the other must unless there is some failure in the components. This setup has even been used on some
passcar motors as well as little engines.

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
 
Thanks for the info.

JR

>

>> Ken,
>> I believe that this is a parallel system as the current goes thru each plug and then to ground and not one plug and then the other plug and
>> ground. I remember working on series, parallel and series parallel diagrams for my one electronics class, if wrong I need to know why.
>>
>> JR
>
> JR,
>
> I think you misunderstood what KenB was saying.
>
> Spark plugs cannot be in parallel as typically defined because only one plug will fire. They cannot be in series as usually defined because the base
> of the plug would have to be insulated at plug firing potential and this would be difficult. There are some gas turbines that do this for the
> igniters, but you don't want to know what those cost.
>
> The Onan like so many other engines with a double ended coil have a secondary winding that has no grounded end. There is a spark plug at each end, so
> spark goes both ways. Ego, if one plug fires the other must unless there is some failure in the components. This setup has even been used on some
> passcar motors as well as little engines.
>
> 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
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
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