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| [GMCnet] Onan Choke Question [message #87446] |
Sat, 05 June 2010 19:25  |
Alan LaVoisne
Messages: 51
Registered: September 2009
Location: Ortonville, MI
Karma: 0
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Hi,
I am trying to understand how the choke on the Onan 6k works. It sees to
close when it starts cold but it seems to refuse to open even after the
generator is fully warmed up. What tells the choke it can be opened back up
(or turned off I guess)?
Thanks,
Alan LaVoisne
75 Glenbrook
Ortonville, MI
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1975 26' Glenbrook
Mostly Original
Ortonville, MI
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| Re: [GMCnet] Onan Choke Question [message #87628 is a reply to message #87514] |
Mon, 07 June 2010 09:56  |
Alan LaVoisne
Messages: 51
Registered: September 2009
Location: Ortonville, MI
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Where does the wire from the choke go? It goes down into the generator.
Does it go to the control board or to some other place inside the engine?
in other words, how does the 12v get applied to the wire after the engine
warms up? I guess it goes to this bimetallac strip which is somewhere
inside?
If you an other info on adjusting the choke that would be useful as well.
The 12v may be the problem. I believe there was no 12v on the line when the
engine was warm and running, but I cannot remember for sure. The choke
closes fine but does not open. I pulled it open and the engine ran fine for
3 hours or so under the load of 1 one A/C and the hot water tank. The it
started to have moments of hunting (the carb is not yet adjusted properly),
during that hunting the choke got pulled closed and again would not open.
Thanks.
On Sun, Jun 6, 2010 at 12:06 PM, Emery Stora <emerystora@mac.com> wrote:
>
> On Jun 5, 2010, at 6:25 PM, Alan LaVoisne wrote:
>
> Hi,
> I am trying to understand how the choke on the Onan 6k works. It sees to
> close when it starts cold but it seems to refuse to open even after the
> generator is fully warmed up. What tells the choke it can be opened back
> up
> (or turned off I guess)?
>
> Thanks,
> Alan LaVoisne
> 75 Glenbrook
> Ortonville, MI
>
>
> There is an electrical connection that goes to a electromagnet in the choke
> that pulls the choke closed. Then there is a thermostatic bimetallic strip
> (spring) that holds the choke open. If the Onan is being started cold the
> bimetalic strip is spread enough so that the lever will completely close the
> choke plate. As the Onan warms up the spring heats up and allows the choke
> to partially close. When at operating temperature the spring has moved far
> enough so that the magnet will not pull the choke toward the closed position
> at all.
>
> Check the wire with a voltmeter to be sure that the magnet is is getting
> voltage when the engine is running. I found on my Onan years ago that the
> choke housing had some rust where it was bolted to the exhaust manifold and
> I was not getting good ground through it. I soldered a wire to the side of
> the choke housing and the other end of the wire to an area on the Onan which
> would not be effected by heat. It has worked well for many years now.
>
> The choke has an adjustment. If you need more information on that let me
> know and I can send it to you.
>
>
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
>
>
>
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1975 26' Glenbrook
Mostly Original
Ortonville, MI
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| Re: [GMCnet] Onan Choke Question [message #87634 is a reply to message #87628] |
Mon, 07 June 2010 10:23 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Alan,
You may want to go to www.bdub.net and download the manual for your Onan.
It will clearly show the wiring of the choke -- it's connected to 12 VDC
ONLY during starting.
A LOT of Onan chokes are inoperative. A few years ago one of our members
identified a surplus rotary solenoid which could easily be adapted as a
replacement. Those specific solenoids are no longer available, but there
are others which could be used as well.
Ken H.
On Mon, Jun 7, 2010 at 10:56 AM, Alan LaVoisne <alan@lavoisne.net> wrote:
> Where does the wire from the choke go? It goes down into the generator...
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Onan Choke Question [message #87638 is a reply to message #87628] |
Mon, 07 June 2010 10:45 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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Alan
As I said in my last message the wire gives 12 volts to the
electromagnet to close the choke.
No wire goes to the bimetallic strip. A bimetallic strip is a
mechanical device which has two layers of metal that expand at
different amounts when heat is applied. That causes the strip to bend.
If you look at a typical house thermostat for a furnace you will see a
coil. This is also a bimetallic strip which coils and uncoils with
room temperature.
So the electromagnet pulls the choke closed and as the Onan starts to
warm up the exhaust heat transfers some heat to the choke housing and
the bimetallic strip starts to heat up and expand which pulls the
choke metal plate away from the electromagnet and the choke begins to
open. When totally warmed up the choke is fully opened.
The choke gets it's 12 volts from the start relay on the control
board. I don't think it gets any power after that when the Onan is
running.
Since you say the choke closes all right you probably don't have an
electrical problem.
If your engine is hunting, as you say, it probably is not a carb
adjustment but probably needs a governor adjustment.
I will send you a couple of files. One is the wiring diagram. The
other will give you directions on how to adjust the carb, the
governor, choke and other things.
Emery Stora
On Jun 7, 2010, at 8:56 AM, Alan LaVoisne <alan@lavoisne.net> wrote:
> Where does the wire from the choke go? It goes down into the
> generator.
> Does it go to the control board or to some other place inside the
> engine?
> in other words, how does the 12v get applied to the wire after the
> engine
> warms up? I guess it goes to this bimetallac strip which is somewhere
> inside?
>
> If you an other info on adjusting the choke that would be useful as
> well.
> The 12v may be the problem. I believe there was no 12v on the line
> when the
> engine was warm and running, but I cannot remember for sure. The
> choke
> closes fine but does not open. I pulled it open and the engine ran
> fine for
> 3 hours or so under the load of 1 one A/C and the hot water tank.
> The it
> started to have moments of hunting (the carb is not yet adjusted
> properly),
> during that hunting the choke got pulled closed and again would not
> open.
>
> Thanks.
>
>
> On Sun, Jun 6, 2010 at 12:06 PM, Emery Stora <emerystora@mac.com>
> wrote:
>
>>
>> On Jun 5, 2010, at 6:25 PM, Alan LaVoisne wrote:
>>
>> Hi,
>> I am trying to understand how the choke on the Onan 6k works. It
>> sees to
>> close when it starts cold but it seems to refuse to open even after
>> the
>> generator is fully warmed up. What tells the choke it can be
>> opened back
>> up
>> (or turned off I guess)?
>>
>> Thanks,
>> Alan LaVoisne
>> 75 Glenbrook
>> Ortonville, MI
>>
>>
>> There is an electrical connection that goes to a electromagnet in
>> the choke
>> that pulls the choke closed. Then there is a thermostatic
>> bimetallic strip
>> (spring) that holds the choke open. If the Onan is being started
>> cold the
>> bimetalic strip is spread enough so that the lever will completely
>> close the
>> choke plate. As the Onan warms up the spring heats up and allows
>> the choke
>> to partially close. When at operating temperature the spring has
>> moved far
>> enough so that the magnet will not pull the choke toward the closed
>> position
>> at all.
>>
>> Check the wire with a voltmeter to be sure that the magnet is is
>> getting
>> voltage when the engine is running. I found on my Onan years ago
>> that the
>> choke housing had some rust where it was bolted to the exhaust
>> manifold and
>> I was not getting good ground through it. I soldered a wire to the
>> side of
>> the choke housing and the other end of the wire to an area on the
>> Onan which
>> would not be effected by heat. It has worked well for many years
>> now.
>>
>> The choke has an adjustment. If you need more information on that
>> let me
>> know and I can send it to you.
>>
>>
>>
>> Emery Stora
>> 77 Kingsley
>> Santa Fe, NM
>>
>>
>>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Onan Choke Question [message #87707 is a reply to message #87661] |
Mon, 07 June 2010 19:30 |
Alan LaVoisne
Messages: 51
Registered: September 2009
Location: Ortonville, MI
Karma: 0
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Member |
|
|
Thanks for all the info. I have been doing a lot of studying. I will be
getting into this thing on Saturday.
Right now I am trying to solve a leak that is in the line that goes from the
carb to the fuel pump. It is leaking fuel from around the flare. I had a
new line made thinking it was the flare as the old flare did not look real
good. I asked for double flare on both ends but I think I got the double
flare on the carb side and single flare on the fuel pump side which is what
the old line was. Does anybody know if that fuel pump side should be single
or can be double? I am not real up on flares sorry to say. I am going to
try and get a new brass 90 that goes into the fuel pump and see if that is
it and also ask what kind of flare I should have. But I am curious what you
all think.
Thanks again.
On Mon, Jun 7, 2010 at 12:55 PM, Emery Stora <emerystora@mac.com> wrote:
>
> On Jun 7, 2010, at 10:38 AM, George Zhookoff wrote:
>
> > Hey Emery,
> >
> > Don't forget the o-ring on the carb adjustment needle. It's what fixed
> > my onan.
> >
> > George Zhookoff
> > 78 EL II
> > Atlanta
> >
>
>
> Yes, I recall telling you about this a long time back.
>
> Alan
>
> The high speed jet that goes into the bottom of the Onan carb has an O ring
> on it. Actually it is a "square" ring as it has flat surfaces. These often
> split and then allow air to leak in along with the fuel and then it is
> difficult to get the Onan to run well.
>
> The original square ring is hard to find, although I remember that Biob
> Burkitt had found a source.
> I have determined though that a standard O ring which is 1/4" OD and 1/8"
> ID will work well. I carry a supply of these in my coach and I have
> replaced many of them on other GMCers coaches at rallies.
>
> If you remove the main jet the initial setting when you put it back in is
> 1-1/4 turns out from the full in position. If you are at higher elevations
> you might have to close it a little -- perhaps 1/4 turn. The low speed
> needle initial setting is 1 turn.
>
>
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
>
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
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List Information and Subscription Options:
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1975 26' Glenbrook
Mostly Original
Ortonville, MI
|
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| Re: [GMCnet] Onan Choke Question [message #87711 is a reply to message #87707] |
Mon, 07 June 2010 19:42 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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Alan
a single flare should work fine as long as the surface of you fitting is not gouged or grooved.
Double flares are used where there is high pressure such as on your brake lines. You don't have much pressure on an Onan fuel line.
Emery Stora
On Jun 7, 2010, at 6:30 PM, Alan LaVoisne wrote:
> Thanks for all the info. I have been doing a lot of studying. I will be
> getting into this thing on Saturday.
>
> Right now I am trying to solve a leak that is in the line that goes from the
> carb to the fuel pump. It is leaking fuel from around the flare. I had a
> new line made thinking it was the flare as the old flare did not look real
> good. I asked for double flare on both ends but I think I got the double
> flare on the carb side and single flare on the fuel pump side which is what
> the old line was. Does anybody know if that fuel pump side should be single
> or can be double? I am not real up on flares sorry to say. I am going to
> try and get a new brass 90 that goes into the fuel pump and see if that is
> it and also ask what kind of flare I should have. But I am curious what you
> all think.
>
> Thanks again.
>
> On Mon, Jun 7, 2010 at 12:55 PM, Emery Stora <emerystora@mac.com> wrote:
>
>>
>> On Jun 7, 2010, at 10:38 AM, George Zhookoff wrote:
>>
>>> Hey Emery,
>>>
>>> Don't forget the o-ring on the carb adjustment needle. It's what fixed
>>> my onan.
>>>
>>> George Zhookoff
>>> 78 EL II
>>> Atlanta
>>>
>>
>>
>> Yes, I recall telling you about this a long time back.
>>
>> Alan
>>
>> The high speed jet that goes into the bottom of the Onan carb has an O ring
>> on it. Actually it is a "square" ring as it has flat surfaces. These often
>> split and then allow air to leak in along with the fuel and then it is
>> difficult to get the Onan to run well.
>>
>> The original square ring is hard to find, although I remember that Biob
>> Burkitt had found a source.
>> I have determined though that a standard O ring which is 1/4" OD and 1/8"
>> ID will work well. I carry a supply of these in my coach and I have
>> replaced many of them on other GMCers coaches at rallies.
>>
>> If you remove the main jet the initial setting when you put it back in is
>> 1-1/4 turns out from the full in position. If you are at higher elevations
>> you might have to close it a little -- perhaps 1/4 turn. The low speed
>> needle initial setting is 1 turn.
>>
>>
>>
>> Emery Stora
>> 77 Kingsley
>> Santa Fe, NM
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> List Information and Subscription Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
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List Information and Subscription Options:
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| Re: [GMCnet] Onan Choke Question [message #87722 is a reply to message #87707] |
Mon, 07 June 2010 21:06 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Alan,
I followed the advice on Gene's website and filed the old fittings off of the line and replaced the hose with regular fuel line.
http://gmcmotorhome.info/generator.html#sleeping
BTW, the fuel pump pressure is only about 1 1/2 psi.
Dennis Sexton
73 GMC
Germantown, TN
USA
-----Original Message-----
From: Alan LaVoisne <alan@lavoisne.net>
To: gmclist@temp.gmcnet.org
Sent: Mon, Jun 7, 2010 7:30 pm
Subject: Re: [GMCnet] Onan Choke Question
Thanks for all the info. I have been doing a lot of studying. I will be
etting into this thing on Saturday.
Right now I am trying to solve a leak that is in the line that goes from the
arb to the fuel pump. It is leaking fuel from around the flare. I had a
ew line made thinking it was the flare as the old flare did not look real
ood. I asked for double flare on both ends but I think I got the double
lare on the carb side and single flare on the fuel pump side which is what
he old line was. Does anybody know if that fuel pump side should be single
r can be double? I am not real up on flares sorry to say. I am going to
ry and get a new brass 90 that goes into the fuel pump and see if that is
t and also ask what kind of flare I should have. But I am curious what you
ll think.
Thanks again.
On Mon, Jun 7, 2010 at 12:55 PM, Emery Stora <emerystora@mac.com> wrote:
>
On Jun 7, 2010, at 10:38 AM, George Zhookoff wrote:
> Hey Emery,
>
> Don't forget the o-ring on the carb adjustment needle. It's what fixed
> my onan.
>
> George Zhookoff
> 78 EL II
> Atlanta
>
Yes, I recall telling you about this a long time back.
Alan
The high speed jet that goes into the bottom of the Onan carb has an O ring
on it. Actually it is a "square" ring as it has flat surfaces. These often
split and then allow air to leak in along with the fuel and then it is
difficult to get the Onan to run well.
The original square ring is hard to find, although I remember that Biob
Burkitt had found a source.
I have determined though that a standard O ring which is 1/4" OD and 1/8"
ID will work well. I carry a supply of these in my coach and I have
replaced many of them on other GMCers coaches at rallies.
If you remove the main jet the initial setting when you put it back in is
1-1/4 turns out from the full in position. If you are at higher elevations
you might have to close it a little -- perhaps 1/4 turn. The low speed
needle initial setting is 1 turn.
Emery Stora
77 Kingsley
Santa Fe, NM
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MCnet mailing list
ist Information and Subscription Options:
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Onan Choke Question [message #88504 is a reply to message #87707] |
Mon, 14 June 2010 08:20 |
Alan LaVoisne
Messages: 51
Registered: September 2009
Location: Ortonville, MI
Karma: 0
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Member |
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The Onan is running like a fine watch. Smooth as can be under the load of
the two A/C's and the hot water tank. I had the fuel line remade and that
fixed the fuel leak. We filed the points and reset the gap on those. The
biggest thing was it seems someone put in the wrong spark plugs. Brand new
spark plugs of the right part number really made a huge difference. We also
did adjust the linkage where the governor attaches to the carburetor.
The only lingering issue is the choke. The choke will pull close on
starting just like it is supposed to. But it will never open. I have to
manually open it and then the Onan runs great. I would like to replace this
choke, but it seems like there is no replacement? I have not taken it apart
yet to see what is going on with it.
Thanks as always for all your advice. Jim K has also helped me a lot via
telephone.
Alan LaVoisne
Ortonville, MI
75 Glenbrook
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1975 26' Glenbrook
Mostly Original
Ortonville, MI
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| Re: [GMCnet] Onan Choke Question [message #88699 is a reply to message #88504] |
Tue, 15 June 2010 15:42 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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That means the bimetalic "spring" which contacts the exhaust manifold is not doing it's job. Many have corroded to the point they won't do anything. You can find replacement chokes if you monitor Ebay. I got a new one last year. However, many have had decent luck running with no choke at all--I did for quite a while. It may crank a bit longer but if you have the prime circuit, I think you'll find that the choke is hardly worth fooling with.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] Onan Choke Question [message #88804 is a reply to message #88699] |
Wed, 16 June 2010 07:57 |
Alan LaVoisne
Messages: 51
Registered: September 2009
Location: Ortonville, MI
Karma: 0
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Member |
|
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So is that the purpose of the "Onan Fuel Pump Primer Switch" that Jim K has?
On Tue, Jun 15, 2010 at 4:42 PM, Bob de Kruyff <NEXT2POOL@aol.com> wrote:
>
>
> That means the bimetalic "spring" which contacts the exhaust manifold is
> not doing it's job. Many have corroded to the point they won't do anything.
> You can find replacement chokes if you monitor Ebay. I got a new one last
> year. However, many have had decent luck running with no choke at all--I did
> for quite a while. It may crank a bit longer but if you have the prime
> circuit, I think you'll find that the choke is hardly worth fooling with.
> --
> Bob de Kruyff
> 78 Eleganza
> Chandler, AZ
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
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1975 26' Glenbrook
Mostly Original
Ortonville, MI
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