Home » Public Forums » GMCnet » [GMCnet] Q-Jet Idle drip - dropped tube
| [GMCnet] Q-Jet Idle drip - dropped tube [message #304612] |
Sat, 30 July 2016 22:05  |
Russell Mehlenbacher
Messages: 128
Registered: June 2010
Karma: 1
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Senior Member |
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'76 Eleganza
I've been having fun...
Some where in the last 1000 miles or so there have been a frustrating set
of symptoms. Erratic idle, erratic tachometer, erratic vacuum readings.
Alternator output goes to zero when the "set level to travel" light comes
on. Misfire-ish events under low voltage limp home.
I've found and corrected a bunch of wiring faults, including the feed to
the HEI, which had only 2 conductors left hanging out of the poorly crimped
connector. Sigh.
The important question:
After observing the imbalance of the passenger side fuel drip and reading
various opinions on Q-Jet symptoms, I decided I needed to see inside. One
of the 4 tubes had fallen out.
Obviously wrong.
I push it in, I can wiggle it out.
I don't think I want to peen it into the air horn...
Epoxy? Knurl the tube?
Opinions requested, experience shared.
Thanks,
Russ
--
Russell Mehlenbacher
Rochester Hills, MI
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Russ & Linda Mehlenbacher
Rochester Hills, Michigan
'76 Eleganza
'74 Sequoia
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| Re: [GMCnet] Q-Jet Idle drip - dropped tube [message #304613 is a reply to message #304612] |
Sat, 30 July 2016 22:11  |
Russell Mehlenbacher
Messages: 128
Registered: June 2010
Karma: 1
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The picture links might be nice:
http://www.gmcmhphotos.com/photos/q-jet/p60979-img-20160730-211800554-1.html
http://www.gmcmhphotos.com/photos/q-jet/p60978-img-20160730-211646856-1.html
On Sat, Jul 30, 2016 at 11:05 PM, Russell Mehlenbacher
wrote:
> '76 Eleganza
> I've been having fun...
> Some where in the last 1000 miles or so there have been a frustrating set
> of symptoms. Erratic idle, erratic tachometer, erratic vacuum readings.
> Alternator output goes to zero when the "set level to travel" light comes
> on. Misfire-ish events under low voltage limp home.
> I've found and corrected a bunch of wiring faults, including the feed to
> the HEI, which had only 2 conductors left hanging out of the poorly crimped
> connector. Sigh.
> The important question:
> After observing the imbalance of the passenger side fuel drip and reading
> various opinions on Q-Jet symptoms, I decided I needed to see inside. One
> of the 4 tubes had fallen out.
> Obviously wrong.
> I push it in, I can wiggle it out.
> I don't think I want to peen it into the air horn...
> Epoxy? Knurl the tube?
> Opinions requested, experience shared.
> Thanks,
> Russ
> --
> Russell Mehlenbacher
> Rochester Hills, MI
>
>
>
--
Russell Mehlenbacher
Rochester Hills, MI
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Russ & Linda Mehlenbacher
Rochester Hills, Michigan
'76 Eleganza
'74 Sequoia
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| Re: [GMCnet] Q-Jet Idle drip - dropped tube [message #304616 is a reply to message #304612] |
Sun, 31 July 2016 06:25 |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
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Just finnished reading Ruggles(can't remember the first name)excelent Quadrajet book for the third time. Don't have it in front of me,,,,,,but,,,, that looks like the tube that feeds gas just as the secondary air flap starts to open. Before the secondary mains come into play by the rising cam.Kind of like a seconday accelerator pump. If you are having problems at part throttle then thats not it. I would very carfully "oval" or squeeze it and drive it in. Wiggle test to see if it would stay. Is your Plunger free??? test with your finger. This enriches part throttle. Rods in the main jets???? How dirty is it inside??? Good luck,,,, get the book. Read it twice!!!
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| Re: [GMCnet] Q-Jet Idle drip - dropped tube [message #304617 is a reply to message #304612] |
Sun, 31 July 2016 08:39 |
Chris Tyler
Messages: 458
Registered: September 2013
Location: Odessa FL
Karma: 7
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^^^ he is right. That should have nothing to do with an idle issue. But it would cause a stumble as the secondarys open
The fact that the tube comes out tells me that carb bas been apart before. You should be able to stake it in place with a little epoxy. Take care not to block the passage or peeen the opening closed
Could you refresh us on the passenger side drip issue? I asssume you mean observing fuel flow th the ventaris while running?
76 Glenbrook
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| Re: [GMCnet] Q-Jet Idle drip - dropped tube [message #304619 is a reply to message #304617] |
Sun, 31 July 2016 09:07 |
Russell Mehlenbacher
Messages: 128
Registered: June 2010
Karma: 1
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1. Occasional bog at WOT
2. Poor & variable idle
a. Fast idle ok
b. Cool idle eventually stalls
c. Hot idle lumpy
d. Manifold floor has fuel puddles
Adjusting idle stop until it runs (into transition?) allows the observation
of fuel in both venturi. Passenger side is 4x or more volume.
Opened up... and surprise!
Russ
On Jul 31, 2016 9:40 AM, "Chris Tyler" wrote:
> ^^^ he is right. That should have nothing to do with an idle issue. But it
> would cause a stumble as the secondarys open
> The fact that the tube comes out tells me that carb bas been apart before.
> You should be able to stake it in place with a little epoxy. Take care not
> to block the passage or peeen the opening closed
>
> Could you refresh us on the passenger side drip issue? I asssume you mean
> observing fuel flow th the ventaris while running?
>
> --
> 76 Glenbrook
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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Russ & Linda Mehlenbacher
Rochester Hills, Michigan
'76 Eleganza
'74 Sequoia
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| Re: [GMCnet] Q-Jet Idle drip - dropped tube [message #304621 is a reply to message #304619] |
Sun, 31 July 2016 09:53 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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You might want to check your throttle vac hose and also possible intake crack
Sent from my iPhone
> On Jul 31, 2016, at 7:07 AM, Russell Mehlenbacher wrote:
>
> 1. Occasional bog at WOT
> 2. Poor & variable idle
> a. Fast idle ok
> b. Cool idle eventually stalls
> c. Hot idle lumpy
> d. Manifold floor has fuel puddles
> Adjusting idle stop until it runs (into transition?) allows the observation
> of fuel in both venturi. Passenger side is 4x or more volume.
> Opened up... and surprise!
>
> Russ
>
>> On Jul 31, 2016 9:40 AM, "Chris Tyler" wrote:
>>
>> ^^^ he is right. That should have nothing to do with an idle issue. But it
>> would cause a stumble as the secondarys open
>> The fact that the tube comes out tells me that carb bas been apart before.
>> You should be able to stake it in place with a little epoxy. Take care not
>> to block the passage or peeen the opening closed
>>
>> Could you refresh us on the passenger side drip issue? I asssume you mean
>> observing fuel flow th the ventaris while running?
>>
>> --
>> 76 Glenbrook
>>
>> _______________________________________________
>> 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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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Q-Jet Idle drip - dropped tube [message #304626 is a reply to message #304621] |
Sun, 31 July 2016 10:09 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Die cast white metal carburetor bodies have a definite life span, and then
their bores and passages start to lose their precise shapes. Not much can
be done to prevent or correct that except melting them down and recasting
them. The throttle bodies are usually cast iron, and they hold their shape
much longer. Old Marvel/Shebler up draft carbs on tractor engines made in
the early 1900's are still in use. If they were pot metal, they would be
long gone. There is still some new/old stock Quadra jet carbs out there,
but the ones specific to the motor home are scarce as hens teeth. If you
did run across one, it would more than likely cost more than fuel
injection. That is one of the challenges of running old stuff. If you have
a good carb, leave it alone and drive it, don't tamper with it. GMC got the
jetting damn close.
Jim Hupy
Salem, Oregon
78 GMC ROYALE 403
On Jul 31, 2016 7:54 AM, wrote:
> You might want to check your throttle vac hose and also possible intake
> crack
>
> Sent from my iPhone
>
>> On Jul 31, 2016, at 7:07 AM, Russell Mehlenbacher
> wrote:
>>
>> 1. Occasional bog at WOT
>> 2. Poor & variable idle
>> a. Fast idle ok
>> b. Cool idle eventually stalls
>> c. Hot idle lumpy
>> d. Manifold floor has fuel puddles
>> Adjusting idle stop until it runs (into transition?) allows the
> observation
>> of fuel in both venturi. Passenger side is 4x or more volume.
>> Opened up... and surprise!
>>
>> Russ
>>
>>> On Jul 31, 2016 9:40 AM, "Chris Tyler"
> wrote:
>>>
>>> ^^^ he is right. That should have nothing to do with an idle issue. But
> it
>>> would cause a stumble as the secondarys open
>>> The fact that the tube comes out tells me that carb bas been apart
> before.
>>> You should be able to stake it in place with a little epoxy. Take care
> not
>>> to block the passage or peeen the opening closed
>>>
>>> Could you refresh us on the passenger side drip issue? I asssume you
> mean
>>> observing fuel flow th the ventaris while running?
>>>
>>> --
>>> 76 Glenbrook
>>>
>>> _______________________________________________
>>> 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
>
> _______________________________________________
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| Re: [GMCnet] Q-Jet Idle drip - dropped tube [message #304653 is a reply to message #304612] |
Sun, 31 July 2016 18:26 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Could be a float /seat issue as well on the idle. Sounds like flooding over. You could have mutiple issues. Split 1" vac hose to pull off or failed pulloff.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Q-Jet Idle drip - dropped tube [message #304656 is a reply to message #304653] |
Sun, 31 July 2016 19:03 |
Russell Mehlenbacher
Messages: 128
Registered: June 2010
Karma: 1
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Senior Member |
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I knurled and put the tube back in. Better, but I agree I have somethings
funny going on. I examined the needle, but forgot to look down the seat
bore. the float is not saturated, (brass) and is set at 1/4".
I may just see if the carb from my 74 wants to come for a visit. Or put it
on the '74 and see if the problem moves with it.
Russ
On Sun, Jul 31, 2016 at 7:26 PM, John R. Lebetski
wrote:
> Could be a float /seat issue as well on the idle. Sounds like flooding
> over. You could have mutiple issues. Split 1" vac hose to pull off or failed
> pulloff.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
> Source America First
>
> _______________________________________________
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--
Russell Mehlenbacher
Rochester Hills, MI
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Russ & Linda Mehlenbacher
Rochester Hills, Michigan
'76 Eleganza
'74 Sequoia
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| Re: [GMCnet] Q-Jet Idle drip - dropped tube [message #305210 is a reply to message #304656] |
Tue, 09 August 2016 13:27 |
Russell Mehlenbacher
Messages: 128
Registered: June 2010
Karma: 1
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Senior Member |
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Some follow up...
Four things that proved important in this cluster. In no particular order...
1. Suspicious gasoline, got more, got better.
2. NOS fuel filter of unknown age, (came with my '74) House brand. When I
removed it, the glue holding the end caps and the media together was
gelatinous goo. It hadn't breached, but I don't have to imagine hard to
think that some of it had migrated into the carb. I pulled the caps and
unrolled the pleats to look inside (clean) and set it on the wood pile for
later. When I went to clean it up days later, no sign of goo or glue. I
think it rained in there one day... Water soluble? (See #1)
3. The carb... who knows who did what. I put the dropped tube back in,
found the needle clip lying in the bottom and put it back. Reassembled.
Backed the idle stop screw all the way off and ended up with the mixture
screws out to around 3 1/2 turns.
4. Somewhere in the middle of all that I advanced the timing a bit until it
was happier.
Hasn't ever run this nice!
Russ
On Sun, Jul 31, 2016 at 8:03 PM, Russell Mehlenbacher
wrote:
> I knurled and put the tube back in. Better, but I agree I have somethings
> funny going on. I examined the needle, but forgot to look down the seat
> bore. the float is not saturated, (brass) and is set at 1/4".
> I may just see if the carb from my 74 wants to come for a visit. Or put it
> on the '74 and see if the problem moves with it.
>
> Russ
>
> On Sun, Jul 31, 2016 at 7:26 PM, John R. Lebetski > wrote:
>
>> Could be a float /seat issue as well on the idle. Sounds like flooding
>> over. You could have mutiple issues. Split 1" vac hose to pull off or failed
>> pulloff.
>> --
>> John Lebetski
>> Woodstock, IL
>> 77 Eleganza II
>> Source America First
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
>
> --
> Russell Mehlenbacher
> Rochester Hills, MI
>
>
>
--
Russell Mehlenbacher
Rochester Hills, MI
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Russ & Linda Mehlenbacher
Rochester Hills, Michigan
'76 Eleganza
'74 Sequoia
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