| [GMCnet] Was this Vapor Lock or ? [message #243247] |
Wed, 12 March 2014 21:46  |
John Olson
Messages: 96
Registered: August 2013
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Does this sound like Vapor Lock or maybe dirty fuel filter or dirty carb
filter (didn't know I had one of those until yesterdays reading)?
I'll do my newbie best to give relevant criteria for diagnosis.
Had two short bits of engine loss of power...
Short sputtering like engine had no fuel (probably didn't for a tic) and
was going to quit. Started to pull over while I could, pushed the gas pedal
one last time and normal operation seemed to resume.
Both sputterings were within 30 mins of each other.
Both sputterings lasted about 5 seconds or so before normal power resumed.
Both sputterings occurred directly after complete stop, then right turn
slightly up hill. This may be a total coincidence.
Outside ambient temps were up to 80 deg high during 500 miles of rolling
hill driving. Eng and Trans temp stayed normal the entire trip, hard roller
hills and all. So there's that.
Had 1/2 full tank at time of sputterings. Did NOT switch senders at any
time that day.
Had just driven 300 miles from Ft Stockton TX to Canyon Lake TX, including
the last 30 or so miles on a VERY SPORTY road named Farm-to-Market 473 in
TX hill country. GMC performed like a champ, even though its driver's hair
turned white on that 60 mph road (how it was posted 60 is beyond me...I did
40mph at best unless free falling down a blind-winding grade. Sporty
indeed. My brakes are super mad at me still.
Previous days driving was 700 miles from Phoenix to Ft Stockton TX. If that
matters somehow.
Any help is appreciated!
John Olson
76 Edgemont
Chicago, IL (soon to be TX domicile resident, though the GMC seems upset
about that)
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John Olson
76 Edgemonte
Fulltime traveler
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| Re: [GMCnet] Was this Vapor Lock or ? [message #243285 is a reply to message #243247] |
Thu, 13 March 2014 08:01  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| John Olson wrote on Wed, 12 March 2014 22:46 |
Does this sound like Vapor Lock or maybe dirty fuel filter or dirty carb filter (didn't know I had one of those until yesterdays reading)?
I'll do my newbie best to give relevant criteria for diagnosis.
Had two short bits of engine loss of power...
Short sputtering like engine had no fuel (probably didn't for a tic) and was going to quit. Started to pull over while I could, pushed the gas pedal one last time and normal operation seemed to resume.
Both sputterings were within 30 mins of each other.
Both sputterings lasted about 5 seconds or so before normal power resumed.
Both sputterings occurred directly after complete stop, then right turn slightly up hill. This may be a total coincidence.
Outside ambient temps were up to 80 deg high during 500 miles of rolling hill driving. Eng and Trans temp stayed normal the entire trip, hard roller hills and all. So there's that.
Had 1/2 full tank at time of sputterings. Did NOT switch senders at any time that day.
Had just driven 300 miles from Ft Stockton TX to Canyon Lake TX, including the last 30 or so miles on a VERY SPORTY road named Farm-to-Market 473 in TX hill country. GMC performed like a champ, even though its driver's hair turned white on that 60 mph road (how it was posted 60 is beyond me...I did 40mph at best unless free falling down a blind-winding grade. Sporty indeed. My brakes are super mad at me still.
Previous days driving was 700 miles from Phoenix to Ft Stockton TX. If that matters somehow.
Any help is appreciated!
John Olson
76 Edgemont
Chicago, IL (soon to be TX domicile resident, though the GMC seems upset about that)
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John,
From you very complete description, I don't think you had a vapor lock issue. I believe that the fuel ran away from the pickup both times and so the pump got a mouthful of air. When the air reaches the carburetor, it blows on through and can actually make the mixture over-rich for a few moments, opening the throttle will let that clear.
The fuel tanks have internal baffles, but enough winding an off-camber can still get the fuel away from the pickups for long enough to cause this. We managed to do this on the Blue Ridge and it was about 40° at the time.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Was this Vapor Lock or ? [message #243296 is a reply to message #243286] |
Thu, 13 March 2014 08:46 |
corleyw
Messages: 130
Registered: June 2007
Location: Battle Ground, WA
Karma: 0
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Senior Member |
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I feel it is likely hot soak vapor lock, if he was stopped long enough. It uses up what fuel is left in the carb, but doesn't get any new fuel for a few seconds, then surges on... He did say it was 80 degrees out. I had that exact same experience a couple times on my Cal trip (no turns involved).
Corley
'76 Glenbrook
29 other vehicles
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| Re: [GMCnet] Was this Vapor Lock or ? [message #243377 is a reply to message #243296] |
Thu, 13 March 2014 17:54 |
John Olson
Messages: 96
Registered: August 2013
Karma: 0
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Member |
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Many thanks guys for the helpful responses and making it through my
nerves-induced novella.
I now feel a little more comfortable about what to look at in case it
happens again.
- Mouthful of air in the pickup sounds logical given the stop/start motion
of each incident. Plus it happening on only two identical starts.
- Will check / replace both fuel filters. Probably a good idea to know how
to do that on our GMC ;).
- Will look at the very real possibility of a pinched line. We had just
completed a winding roller coaster 30 miles so a few body pads shifted or
even missing would not surprise me.
John Olson
76 Edgemonte
Chicago, IL (In Canyon Lake, TX now, then making our way toward Montgomery).
On Thu, Mar 13, 2014 at 8:46 AM, Corley Wooldridge <corley@corleyw.com>wrote:
>
>
> I feel it is likely hot soak vapor lock, if he was stopped long enough.
> It uses up what fuel is left in the carb, but doesn't get any new fuel for
> a few seconds, then surges on... He did say it was 80 degrees out. I had
> that exact same experience a couple times on my Cal trip (no turns
> involved).
> --
> Corley
> '76 Glenbrook
> 29 other vehicles
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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John Olson
76 Edgemonte
Fulltime traveler
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