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Discussion Starter · #1 ·
Hi. I have owned my 1968 el camino for over 14 years. Through all the 14 years I have owned it, I've had some kinda pressure building up in the gas tank. I want to get this problem fixed but just don't know what to do. I bought a new gas cap a few weeks back and that didn't do a thing. Even sometimes when I'm driving, I can smell a very strong feums and then when I stop my el camino turn off the engine and go and open the gas cap, a LOT of air releases. But shortly the pressure will just builds up again. Anyone know a solution to fixing this problem? I would appreciate any suggestions that I could do to resolve this. Thanks!
Michael

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Michael Minery
Orange, California
1968 Malibu El Camino
<A HREF="http://www.angelfire.com/ca/mineryhomepage/1968elcamino.html" TARGET=_blank>My 1968 El
Camino page</A>
 

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Someone on there can give you a technical explanation for this, but some pressure buildup is normal. Sometime in the 66-68 time frame, with the start of the pollution control stuff, manufacturers began using non-vented gas caps to ensure that fumes would be forced back through the vapor canister. If you are experiencing excessive pressure buildup, you may have a problem with the canister.
 

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Discussion Starter · #3 ·
Well, there is no canister on my 68 el camino. Is there supposed to be?

<BLOCKQUOTE>quote:</font><HR>Originally posted by vettefella:
Someone on there can give you a technical explanation for this, but some pressure buildup is normal. Sometime in the 66-68 time frame, with the start of the pollution control stuff, manufacturers began using non-vented gas caps to ensure that fumes would be forced back through the vapor canister. If you are experiencing excessive pressure buildup, you may have a problem with the canister.<HR></BLOCKQUOTE>
 

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My '65 EC has a vented gas cap stock. No pressure build-up. $20 for a reprint of the chassis service manual for your year would be money well spent. You can find accurate information/answers for lots of questions like yours.

My $0.02
 

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The gas caps for the 66 Chevelle was non vented. The tank had a vent on the passenger side front at the top. I assume the EC's would have a vented tank as well?

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Tom Wood
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Is it possible to put a vented cap on a tank without a stock vented cap, and then block off the external vents?

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Craig Crisafulli
383 Powered 69 Malibu
Track times coming spring 2002!!
 

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<BLOCKQUOTE>quote:</font><HR>Originally posted by michaelem:
I would appreciate any suggestions that I could do to resolve this. Thanks!
Michael
<HR></BLOCKQUOTE>

Since it's an El Camino, if it were me, I would take the new cap back and exchange it for a vented cap

cars are a different story because the filler neck is in back, a vented cap will let gas dump on the ground on quick start ups




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Dean Call
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Discussion Starter · #8 ·
Ok got underneith my el camino today and look at the gas tank on the passenger side of my el camino and no vent or anything was found on either side. The new gas cap I bought recently is vented but doesn't release the pressure. Any ideas anyone?

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Michael Minery
Orange, California
1968 Malibu El Camino
<A HREF="http://www.angelfire.com/ca/mineryhomepage/1968elcamino.html" TARGET=_blank>My 1968 El
Camino page</A>
 

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I may be wrong here but the tank is vented or has a vented cap to allow gas to flow into the carb. As fuel is used the vent, which is like a check valve, allows intake of air to eliminate creating a vacumn and hindering flow. The pressure builds from temp change or evaporation because the vent only operates in the other direction.

I believe the pressure buildup is common and not detrimental unless you have an open flame around when opening the gas cap.

Someone correct me if I'm wrong.



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Elcaminos are special!
I'd rather walk around with a Chevrolet hubcap in my hand than drive a Ford


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I agree with BigJames here. My Chevelle came with a vented cap when I bought it new in 1970. During the gas crisis of 1973/74 I purchased a locking cap from a Gulf Gasoline dealer which turned out to be non-vented. The seal was so tight that after awhile, the bottom of the fuel tank got sucked in! Everytime I took that cap off, a rush of air could be heard. The air was rushing INTO the neck. This happened on both mine AND my wife's '70 Chevelle. The cap should be vented, unless the car came equipped with a cannister.

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MalibuJerry350
TC Member #1279
Original owner '70 Chevelle.
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after 3 new vented gas caps for my chevelle wouldn't VENT, a LONG tome owner of a 70 SS told me to find the smallest drill bit i could find and drill a hole all the way through. i did and evrything has been fine since...and no gas dribble out of the cap either.

car thoughts, wally

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Astro Blue '70 SS Christmas Chevelle
Build/Born on Date (12D)
4th Week of December,1969

Wally Sowles TC#1448

Smokin' TIRES won't give you cancer.....
 

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The 69 has a non vented cap. I believe the 68 does also. There should be a check valve type vent on the top of the tank. It's job is to let air into the tank, but not let fumes out.
Yours could be plugged or broken. I have gone through everything described in this thread, including drilling a hole in the cap. I have a replacement gas tank from Auto-Zone for a 69, and it has several extra vent lines. I used one of these an put a hose with a fuel filter attached and screwed it high up in the tunnel for the rear end. I believe this is where the original hose and check valve was clamped. Oh yeah, I sucked in my gas tank too and bent the brand new sending unit, so now my gas gage is off by 1/4 of a tank.
 

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Had a similiar problem with a 67 Cutlass. Previous owner had blocked two outlets that appeared to be vent tubes. Even with a chassis manual I couldn't figure out how the vents were supposed to be hooked up. I blocked them a little better than he had and drilled the smallest hole I could in the top of the non vented cap. Has worked OK for the last year and a half, only problem is if that if I run it up on ramps with anything over 3/4 of a tank gas leaks out. Don't know the safety ramifications of this if I ever get ass ended by a SUV!
 

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michaelem;
The early Elkys and wagons used a vented cap. There are no other hoses to vent this tank but the short 18" rubber line from the top of the filler neck back to the tank. My guess is your gas cap is not venting. Drill the hole before your tank collapse. Replace the short rubber line or at least clear it out with a air line. Seadans use a no vented cap.

Roy Seattle
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Discussion Starter · #16 ·
Well, thanks to all that replied to my gas pressure problem. I guess for now I'll do the (drill a small hole in the gas cap). A question though? What about the rubber o-ring inside the gas cap? Do you drill through that also?

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Michael Minery
Orange, California
1968 Malibu El Camino
<A HREF="http://www.angelfire.com/ca/mineryhomepage/1968elcamino.html" TARGET=_blank>My 1968 El
Camino page</A>
 
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