Home » Public Forums » GMCnet » [GMCnet] Sputter n choke
| [GMCnet] Sputter n choke [message #251973] |
Wed, 11 June 2014 14:25  |
Tom Whitton
Messages: 235
Registered: February 2004
Location: Paducah, KY
Karma: 0
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Senior Member |
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Johnny,
I had similar problems when I first bought my GMC 13-years ago. Finding the problem was exasperating. I won't go into that. The trouble turned out to be a clogged Liquid Fuel Separator, located in the left rear wheel well. The little plastic ball inside the thing was stuck closed. I took it off, cleaned and put it back on. At the same time, I replaced the Vapor Canister, located on the frame in front of the right front wheel. My fuel sputtering/quitting problem went away and has not come back. Worth a try.
Tom Whitton
26 foot updated GMC
Paducah, KY
Message: 3
Date: Wed, 11 Jun 2014 10:28:17 -0600
From: Johnny Bridges
Subject: [GMCnet] Sputter n choke
To: gmclist@temp.gmcnet.org
Message-ID:
Content-Type: text/plain; charset="utf-8"
Well, it isn't a sputter, it's a quit. When it's hot, my coach quits - or tries to - when shifting. I found out yesterday, I can >usually< nurse it
back to life with the accelerator pump but not always. This is the syndrome which put me beside the road on the way to Louisville. I redid the fuel
feed, but going over the mountains, it quit on the way to Bean Station. Once cooled off, it took it on in. Now, it just doesn't want to run when it's
warm and shifting. The temp gauge runs square on the quarter mark in the summer, this is up a bit. Last year, it hit nearly half going over
Monteagle but gave no problems and went down on the downhill side. Also went down going to BS coming down the backside of the hill, which makes me
think the cooling system is working. Both times it's quit, I pull the fuel line to the pump input, nothing there. Interestingly, the output line
pulses when the engine's running. Going to Louisville, I pulled the air cleaner and pumped, no gas in the carb, but clear filter.
My thoughts are, it's vapor locking back down the line someplace, or the carb is getting so hot the pressure sends fuel back towards the tank. Or the
pump is dying, or the ignition module gets too hot. I am however open to other ideas.
This weekend is committed to getting my 'travel truck' engine installed and it running. The toad isn't really a good commuter, it's missing many of
the amenities like A/C, an automatic, etc. Once it's going, the GMC will get the tanks pulled out and checked, a new fuel pump, and a new ignition
module. I'll keep the current module as a spare. Hopefully, all of this will highlight whatever's making the thing quit running.
--johnny
'76 23' transmode norris
Braselton ga
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| Re: [GMCnet] Sputter n choke [message #251975 is a reply to message #251973] |
Wed, 11 June 2014 14:43  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Johnny, what you describe sounds like an ignition related problem. The
ignition coil in particular. They display some unusual characteristics that
resemble vapor lock problems. Turns out that when cold, they exhibit normal
behaviors, and as they warm up, they go open circuit or to a high
resistance mode. Open circuit just stops running, and high resistance
mimics vapor lock. Ken Henderson had a problem and ran a series of tests
with a suspect coil where he measured continuity and resistance at various
temperatures. His coil proved to be bad when at certain temperatures. Might
be worth a try to check your spark when this happens again. JWIWD.
Jim Hupy
Salem, Or.
78 GMC ROYALE 403 in Pontiac, Illinois on the route 66 rolling rally.
On Jun 11, 2014 2:25 PM, "Tom Whitton" wrote:
> Johnny,
>
> I had similar problems when I first bought my GMC 13-years ago. Finding
> the problem was exasperating. I won't go into that. The trouble turned
> out to be a clogged Liquid Fuel Separator, located in the left rear wheel
> well. The little plastic ball inside the thing was stuck closed. I took
> it off, cleaned and put it back on. At the same time, I replaced the Vapor
> Canister, located on the frame in front of the right front wheel. My fuel
> sputtering/quitting problem went away and has not come back. Worth a try.
>
> Tom Whitton
> 26 foot updated GMC
> Paducah, KY
>
>
> Message: 3
> Date: Wed, 11 Jun 2014 10:28:17 -0600
> From: Johnny Bridges
> Subject: [GMCnet] Sputter n choke
> To: gmclist@temp.gmcnet.org
> Message-ID:
> Content-Type: text/plain; charset="utf-8"
>
> Well, it isn't a sputter, it's a quit. When it's hot, my coach quits - or
> tries to - when shifting. I found out yesterday, I can >usually< nurse it
> back to life with the accelerator pump but not always. This is the
> syndrome which put me beside the road on the way to Louisville. I redid the
> fuel
> feed, but going over the mountains, it quit on the way to Bean Station.
> Once cooled off, it took it on in. Now, it just doesn't want to run when
> it's
> warm and shifting. The temp gauge runs square on the quarter mark in the
> summer, this is up a bit. Last year, it hit nearly half going over
> Monteagle but gave no problems and went down on the downhill side. Also
> went down going to BS coming down the backside of the hill, which makes me
> think the cooling system is working. Both times it's quit, I pull the fuel
> line to the pump input, nothing there. Interestingly, the output line
> pulses when the engine's running. Going to Louisville, I pulled the air
> cleaner and pumped, no gas in the carb, but clear filter.
> My thoughts are, it's vapor locking back down the line someplace, or the
> carb is getting so hot the pressure sends fuel back towards the tank. Or the
> pump is dying, or the ignition module gets too hot. I am however open to
> other ideas.
> This weekend is committed to getting my 'travel truck' engine installed
> and it running. The toad isn't really a good commuter, it's missing many of
> the amenities like A/C, an automatic, etc. Once it's going, the GMC will
> get the tanks pulled out and checked, a new fuel pump, and a new ignition
> module. I'll keep the current module as a spare. Hopefully, all of this
> will highlight whatever's making the thing quit running.
>
> --johnny
> '76 23' transmode norris
> Braselton ga
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Sputter n choke [message #252006 is a reply to message #251973] |
Thu, 12 June 2014 06:06 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Both suggestions are now on the list. I'll bag the vapor separator this evening, it's easy to get at. My experience with dying cols is/has been slightly different that this presents, but it's still worth a look. The 455 may behave differently with lousy spark than the other stuff I've messed with. Thanks guys!
--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
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