Another Onan thread! Choke and/or throttle issue

[Palmerdad]

You all helped me to get this Onan 6k genset running several months ago and I am very thankful. The carb has now been rebuilt by the good folks at
Walbro and a new board will soon be ordered from Applied. (I am still jumpering it in the meantime.) But one issue still seems to be lingering which
I have now gotten around to exploring that involves the choke. It keeps wanting to close prematurely and choke out the engine. It was around the
freezing mark today but the Onan started right up and after about 5 minutes of holding the choke open manually I was finally able to ease it back and
it would run under it's own power. I shut it down for 20 minutes and started it up again and shot this video of it doing it again.

https://www.youtube.com/watch?v=UcTikFSNdOo&feature=youtu.be

Do I need to adjust the choke cable closer up on the wire or is there something sticking in the throttle and keeping it from moving the auto choke
correctly?
--
-James Palmer, Traverse City, MI
1976 Eleganza

 

[Jim Hupy]

The electric thermostatic coil is grounded through contact with the
manifold that it is fastened to. The mating surfaces are nearly always
rusted to the point that poor electrical contact is the result. Use your
favorite pentetrating oil on the hold down fasteners, carefully, remove,
clean with wire brush or sandpaper, replace the star washers with new ones,
and re-tighten. If that does not fix it, order a new electric choke from
applied gmc.
Jim Hupy
Salem, Oregon
78 GMC ROYALE 403

> You all helped me to get this Onan 6k genset running several months ago
> and I am very thankful. The carb has now been rebuilt by the good folks at
> Walbro and a new board will soon be ordered from Applied. (I am still
> jumpering it in the meantime.) But one issue still seems to be lingering
> which
> I have now gotten around to exploring that involves the choke. It keeps
> wanting to close prematurely and choke out the engine. It was around the
> freezing mark today but the Onan started right up and after about 5
> minutes of holding the choke open manually I was finally able to ease it
> back and
> it would run under it's own power. I shut it down for 20 minutes and
> started it up again and shot this video of it doing it again.
>
> https://www.youtube.com/watch?v=UcTikFSNdOo&feature=youtu.be
>
> Do I need to adjust the choke cable closer up on the wire or is there
> something sticking in the throttle and keeping it from moving the auto choke
> correctly?
> --
> -James Palmer, Traverse City, MI
> 1976 Eleganza
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[emerystora]

The choke is grounded to the manifold and it often gets very rusty and no longer makes good contact. Years ago I soldered a 10 gauge wire to the side of the choke and fastened the other end of the wire to a screw in the frame holding the Onan.
No more problems with the choke.

Emery Stora
77 Kingsley
Frederick, CO

>
> You all helped me to get this Onan 6k genset running several months ago and I am very thankful. The carb has now been rebuilt by the good folks at
> Walbro and a new board will soon be ordered from Applied. (I am still jumpering it in the meantime.) But one issue still seems to be lingering which
> I have now gotten around to exploring that involves the choke. It keeps wanting to close prematurely and choke out the engine. It was around the
> freezing mark today but the Onan started right up and after about 5 minutes of holding the choke open manually I was finally able to ease it back and
> it would run under it's own power. I shut it down for 20 minutes and started it up again and shot this video of it doing it again.
>
> https://www.youtube.com/watch?v=UcTikFSNdOo&feature=youtu.be
>
> Do I need to adjust the choke cable closer up on the wire or is there something sticking in the throttle and keeping it from moving the auto choke
> correctly?
> --
> -James Palmer, Traverse City, MI
> 1976 Eleganza
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[Palmerdad]

I wish I had the machine in front of me when I read and write these replies but in Northern Michigan you need to take the storage you can come by or
you're working in a snow drift! Applied doesn't have any electric chokes and they look like they're quite pricey anyways... So when I next go over
there what am I looking for to remove and clean up? Maybe it will make sense when I look at it again but I thought I would ask for a little more
detail so I know what I'm aiming for before heading back out.
--
-James Palmer, Traverse City, MI
1976 Eleganza

 

[a.]

> I wish I had the machine in front of me when I read and write these replies but in Northern Michigan you need to take the storage you can come by
> or you're working in a snow drift! Applied doesn't have any electric chokes and they look like they're quite pricey anyways... So when I next go
> over there what am I looking for to remove and clean up? Maybe it will make sense when I look at it again but I thought I would ask for a little
> more detail so I know what I'm aiming for before heading back out.
You might unbolt the choke from the exhaust manifold and clean up the connection area between the choke and the manifold. You will want to soak the
bolts with several applications of penetrating oil over several days before you try that.

Or you could drill a small hole in the skirt of the choke and use a self-tapping sheet metal screw with a star washer to connect a wire from that
skirt to someplace else on the Onan.

All of that is assuming that the choke is not working because the ground connection is corroded. If that's not what's wrong, and you need a new choke,
you are going to have a hard time finding one, or cobbling up something that will work.
--
73 23' Sequoia 4 Sale
73 23' CanyonLands Parts Unit 4 Sale
Upper Alabama
"When I grow up I am going to be a curmudgeon."

 

[jim miller]

> But one issue still seems to be lingering which I have now gotten around to exploring that involves the choke. It keeps wanting to close prematurely and choke out the engine.

The choke actuator’s job is to close the choke in one and only one circumstance: when the starter is ENERGIZED on a COLD engine. The actuator is de-energized at all other times (Onan 6kW service manual, pp27, top right).

If the starter is not energized OR the engine is warm then a properly installed and adjusted actuator will not try to close the choke; it will try to OPEN it - and in fact there is a coil spring in the choke actuator which tries to hold the choke open at all times.

Electrical problems such as a rusty exhaust manifold or a wiring problem to the choke actuator solenoid as others have described can only result in hard starts - which is the opposite of the problem that you have described.

Is there any chance that you installed the choke linkage in a reversed sense when you installed your newly rebuilt carb? There are other choke actuator failures that can account for what you are describing but they are unlikely compared to an error in the linkage orientation.

—Jim

Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH

 

[Ken B]

>
> > But one issue still seems to be lingering which I have now gotten around to exploring that involves the choke. It keeps wanting to close
> > prematurely and choke out the engine.
>
> The choke actuator's job is to close the choke in one and only one circumstance: when the starter is ENERGIZED on a COLD engine. The actuator is
> de-energized at all other times (Onan 6kW service manual, pp27, top right).
>
> If the starter is not energized OR the engine is warm then a properly installed and adjusted actuator will not try to close the choke; it will try
> to OPEN it - and in fact there is a coil spring in the choke actuator which tries to hold the choke open at all times.
>
> Electrical problems such as a rusty exhaust manifold or a wiring problem to the choke actuator solenoid as others have described can only result
> in hard starts - which is the opposite of the problem that you have described.
>
> Is there any chance that you installed the choke linkage in a reversed sense when you installed your newly rebuilt carb? There are other choke
> actuator failures that can account for what you are describing but they are unlikely compared to an error in the linkage orientation.
>
> --Jim
>
> Jim Miller
> 1977 Eleganza
> 1977 Royale
> Hamilton, OH
>
>
>
>
> _______________________________________________

That is a good thought Jim. I never would have come up with that one.

Jim is also correct on the electric. Applying electric to the choke closes it. Since you have the board jumpered, I'm wondering if you are also
jumpering +12 to the choke ot have some kind of board failure.

After you have tried Jim's suggestion, if it still fails, try unplugging the choke from the board and see if it still does the same thing.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[jim miller]

> Jim is also correct on the electric. Applying electric to the choke closes it. Since you have the board jumpered, I'm wondering if you are also jumpering +12 to the choke ot have some kind of board failure.

Hi Ken,

The choke solenoid is wired to the switched side of the starter pilot solenoid that is located directly below the control board; therefore if the choke is staying energized then the starter would be running too.

73, Jim N8ECI

Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH

 

[Ken B]

>
> > Jim is also correct on the electric. Applying electric to the choke closes it. Since you have the board jumpered, I'm wondering if you are
> > also jumpering +12 to the choke ot have some kind of board failure.
>
> Hi Ken,
>
> The choke solenoid is wired to the switched side of the starter pilot solenoid that is located directly below the control board; therefore if the
> choke is staying energized then the starter would be running too.
>
> 73, Jim N8ECI
>
> Jim Miller
> 1977 Eleganza
> 1977 Royale
> Hamilton, OH


I realize that Jim,

IF... it is plugged on the correct pin of the board. I did not state that so as not to confuse the OP. I just wanted him to unplug it and see if it
makes any difference. If it did then, I was going to tell him to check where it was wired on the board.

I could have told him to check it for +12 v with a meter, but I felt this way was simpler.

I expect that he will unplug it and it will nto make any difference.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[Palmerdad]

Thanks for these suggestions. I will give them a shot when I head over there next.
--
-James Palmer, Traverse City, MI
1976 Eleganza

 

[emerystora]

James -
The reason that I soldered the wire to the choke housing instead of using a sheet metal screw as someone suggested is because of the possibility of the screwed connection also getting rusted and corroded. The Onan will pull in lots of air to that area and also rain, fumes from the motorhome running next to it, etc.

Emery Stora

>
> Thanks for these suggestions. I will give them a shot when I head over there next.
> --
> -James Palmer, Traverse City, MI
> 1976 Eleganza
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[a.]

> James -
> The reason that I soldered the wire to the choke housing instead of using a sheet metal screw as someone suggested is because of the possibility
> of the screwed connection also getting rusted and corroded. The Onan will pull in lots of air to that area and also rain, fumes from the motorhome
> running next to it, etc.
>
> Emery Stora
True. At least the sheet metal screw connection is easy to service.
--
73 23' Sequoia 4 Sale
73 23' CanyonLands Parts Unit 4 Sale
Upper Alabama
"When I grow up I am going to be a curmudgeon."

 

[john r. lebetski]

Jim Miller is correct here (no surprise). Follow what he said but meter choke + while this problem is happening in case some PO has sourced choke
power from the wrong place. It should be zero when not cranking. So I don't cringe-- if you are inclined to drill the cover be sure to firmly wrap the
bit with tape or put a collet on the small bit with only 1/8" available. Otherwise you have a very good chance of drilling into the magnet coil when
you punch through -- says Murphy.
--
John Lebetski
Woodstock, IL
77 Eleganza II
Source America First

 

[Palmerdad]

So I took a look at it today and the area where the wire comes into the choke assembly doesn't look bad, still has it's paint. None-the-less I
sprayed the nuts holding the choke on (they are quite rusty) and will let it sit for a day before trying to remove the choke to clean it up. I did
fire it up without #12 attached on the board and it made no difference. However, I am interested in Jim Miller's comment about re-installing it
wrong. I don't see a way it could be attached differently but the default position for the choke plate is closed. (Limiting the supply of air
getting in from the filter.) Is the default supposed to be open 90 degrees only closing once running???
--
-James Palmer, Traverse City, MI
1976 Eleganza

 

[Palmerdad]

One more thought, the carb was very clean when we got the machine. I only sent it away to Walbro as I didn't want to mess with tiny springs, and
gaskets and such and something obviously wasn't right with it. I wonder if it was so clean because a PO cleaned it and then put it back on wrong. I
am wondering if I were to adjust the screw on the wire holding it to the choke if I could make the choke wire stretch far enough to connect the carb
arm and hold it in the open position as the default??? Is this what has happened to this at some point? I guess the answer will depend on whether
it's default is supposed to be open (and closing when starting in the cold) or closed (opening once it gets running.
--
-James Palmer, Traverse City, MI
1976 Eleganza

 

[christopher brewer]

Per Jim Millers response
"The choke actuator's job is to close the choke in one and only one circumstance: when the starter is ENERGIZED on a COLD engine. The actuator is
de-energized at all other times (Onan 6kW service manual, pp27, top right)."
--
Christopher Brewer
Chattanooga Tn
1975 Palm Beach
Still mostly original
EV-6010 Norcold 962 Sully's Wireless Air Mach 15k
Gettin better, $1 at a time...

 

[Jim Hupy]

But, it has a thermostatic coil spring that assists in opening the choke
when the exhaust heats the manifold. IF THAT SPRING IS INOPERATIVE DUE TO
IMPROPER ADJUSTMENT (LIKELY), OR BROKEN (IT HAPPENS) , THEN, the choke will
not fully open and the Onan engine will run like crap. Wasn't that the
original complaint?
Jim Hupy
Salem, Or
78 GMC ROYALE 403

Per Jim Millers response
"The choke actuator's job is to close the choke in one and only one
circumstance: when the starter is ENERGIZED on a COLD engine. The actuator
is
de-energized at all other times (Onan 6kW service manual, pp27, top right)."
--
Christopher Brewer
Chattanooga Tn
1975 Palm Beach
Still mostly original
EV-6010 Norcold 962 Sully's Wireless Air Mach 15k
Gettin better, $1 at a time...

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[a.]

> One more thought, the carb was very clean when we got the machine. I only sent it away to Walbro as I didn't want to mess with tiny springs, and
> gaskets and such and something obviously wasn't right with it. I wonder if it was so clean because a PO cleaned it and then put it back on wrong.
> I am wondering if I were to adjust the screw on the wire holding it to the choke if I could make the choke wire stretch far enough to connect the
> carb arm and hold it in the open position as the default??? Is this what has happened to this at some point? I guess the answer will depend on
> whether it's default is supposed to be open (and closing when starting in the cold) or closed (opening once it gets running.
Jim Miller said it needs to be open by default and the choke closes it when the starter is engaged.

You can take that to the bank.

I wonder if the rebuild resulted in the choke shaft and butterfly getting put back in disoriented?
--
73 23' Sequoia 4 Sale
73 23' CanyonLands Parts Unit 4 Sale
Upper Alabama
"When I grow up I am going to be a curmudgeon."

 

[Ken B]

> But, it has a thermostatic coil spring that assists in opening the choke
> when the exhaust heats the manifold. IF THAT SPRING IS INOPERATIVE DUE TO
> IMPROPER ADJUSTMENT (LIKELY), OR BROKEN (IT HAPPENS) , THEN, the choke will
> not fully open and the Onan engine will run like crap. Wasn't that the
> original complaint?
> Jim Hupy

Yes.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[jim miller]

> But, it has a thermostatic coil spring that assists in opening the choke when the exhaust heats the manifold. IF THAT SPRING IS INOPERATIVE DUE TO IMPROPER ADJUSTMENT (LIKELY), OR BROKEN (IT HAPPENS) , THEN, the choke will not fully open and the Onan engine will run like crap.

Beg to differ..with all due respect.

There are two springs in the choke actuator and I have a brand new one right in front of me that I am referencing as I write this message.

1. Coiled spring on the actuator shaft; located inside the actuator body. This spring ALWAYS tries to hold the choke OPEN. Always.

2. Thermostatic leaf spring that senses the temperature of the exhaust manifold. This spring has one and only one purpose - to prevent the electric solenoid from pulling the actuator arm and closing the choke plate if the engine is hot. The thermostatic spring is designed to collapse when hot and thus disconnect the mechanical linkage between the solenoid plate and the actuator arm. This latter spring does NOT have any influence on holding the choke open OR closed - it just disconnects the solenoid linkage.

Said another way:

If the engine is HOT then the collapsed thermostatic spring inhibits the action of the solenoid and the coiled spring then holds the choke open. No choking takes place.

If the engine is COLD then the solenoid has full authority to pull the actuator arm, override the coiled spring and thus choke the engine.

The original complaint was an engine that is choked **after warmup**. The only actuator failure that can cause that symptom is a failure of the coiled spring mentioned in #1 above. I think it is more likely that the actuator is working just fine and that his linkage is reversed - but of course this is the GMCnet and as usual a simple problem to troubleshoot has devolved into dueling experts and the person that asked the question is probably totally confused.

—Jim

Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH