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09-15-2011, 01:46 PM
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#1 |
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Senior Member
Join Date: Aug 2002
Location: Valley Center KS
Posts: 3,525
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fuel tank gas cap
In my 69 pickup, I recently got a gas cap for a 69 3/4 ton from LMC. When I take the cap off, you could hear air being sucked in or out. I figured they gave me the wrong gas cap.
So I got another one from another company while at the goodguys show. It has a blue vent thing in the middle (inside) of the cap. When I took it off, same thing. What's up with this? |
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09-15-2011, 04:39 PM
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#2 |
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Active Member
 
Join Date: Jul 2007
Location: Centrally located between Houston, Austin and Waco. BCS area.
Posts: 7,947
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Re: fuel tank gas cap
If you have the correct cap it should have a hole in the middle with that has a spring loaded plunger valve. This regulates the tank pressure which usually is around 3psi if I remember correctly.
The hole is about 3/16th (plus or minus) of an inch and if you insert a small object you can feel the spring loaded vent cap moving. |
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09-15-2011, 05:54 PM
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#3 |
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Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: fuel tank gas cap
you should b able to get the right cap at about any autoparts store
__________________
71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY |
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09-15-2011, 06:01 PM
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#4 | |
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Senior Member
Join Date: May 2002
Location: Hammond, WI
Posts: 1,797
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Re: fuel tank gas cap
that's normal. if you unscrew the cap on a new car, it does the same thing. the newer cars also have a warning stating "Caution, contents may be under pressure"
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Mike 2001 Dakota R/T - Silver CC - 1 of 1671 •360 w/46RE •392 limited slip 1972 Chevy Suburban - Turquoise/Black 1969 Chevy C/10 - Blue LWB •350 w/ 700R4 •3.73 posi •PS PB A/C - SOLD  Using your turn signal is not "giving information to the enemy" 67-72 FAQ Quote:
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09-15-2011, 11:29 PM
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#5 |
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Grandpa in the rustmobile...
Join Date: Nov 2008
Location: Spokane WA/Viola TN
Posts: 11,422
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Re: fuel tank gas cap
you sure nightmare, cause I can hear my tank contract when i take mine off too LOL
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John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4 |
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09-15-2011, 11:32 PM
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#6 |
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Registered User
Join Date: Apr 2007
Location: Mcgraw, ny
Posts: 204
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Re: fuel tank gas cap
very strange mine started doing it too! changed the cap and still does it occasionally.
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09-16-2011, 03:31 AM
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#7 | |
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Registered User
Join Date: Jan 2005
Location: Clearlake Oaks CA
Posts: 1,716
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Re: fuel tank gas cap
Quote:
Locking Gas Cap for my 72GMC. Everyone listed one for UP TO a 71 (but not 72). I bought probably 3 different types, and NONE of them fit. Either the "Tangs" would be off or the "Body" of the Cap, was too big. I finally gave up and went to Kragens and bought a Locking Gas Cap for my 72. Iwhen the gut pulled it out of the Box, it was CHROME (w/Blue Ring) as you described. I was happier than "White On Rice". Mine had the EEC too. Just thought I'd share. 
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Hello members... I'd like you to know that I sold, my 72 GMC (Ratikle), back in November of 2011. I don't visit the site much anymore, but please feel free, to drop me a private message. RIP...."RATIKLE" |
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09-16-2011, 08:04 AM
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#8 |
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Just a car guy
Join Date: Feb 2006
Location: New Washington, IN
Posts: 991
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Re: fuel tank gas cap
I have posted about this before, I bought 4 or 5 caps from various sources and never could find the right one.
http://67-72chevytrucks.com/vboard/s...d.php?t=366184 Swapped yo a vented blazer tank so it's not a concern for me now. Posted via Mobile Device
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1955 belair Blown Pro Street cruiser 1971 Camaro Pro Touring 1973 Vega Drag Car 1970 C20 tow rig Last edited by OJ1988; 09-16-2011 at 08:19 AM. |
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09-16-2011, 08:28 AM
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#9 | |
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Senior Member
Join Date: Aug 2002
Location: Valley Center KS
Posts: 3,525
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Re: fuel tank gas cap
Quote:
Oh well....maybe this is just the way they're supposed to be. And maybe we're just used to old gas caps that the seal is worn out, so it doesn't pressurized. |
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09-16-2011, 09:07 AM
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#10 |
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Just a car guy
Join Date: Feb 2006
Location: New Washington, IN
Posts: 991
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Re: fuel tank gas cap
The cap is the vent. It has to vent or these tanks will get a vacum in them.
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1955 belair Blown Pro Street cruiser 1971 Camaro Pro Touring 1973 Vega Drag Car 1970 C20 tow rig |
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