gas tank question

64slick · Post by **64slick** » April 10, 2007, 6:47 pm

On my 64 slick my tank pressurizes, does anybody know if they are suppose to, it really uses the gas up, and gas caps are designed to release the vacuum cause by the pump but my tank keeps building pressure

ethan_lanning · Post by **ethan_lanning** » April 10, 2007, 7:14 pm

I have the same problem and when it gets hot outside sometimes it will spray gas out.

DocDave · Post by **DocDave** » April 10, 2007, 8:00 pm

I have in the past drilled a 1/16 inch hole in the cap, but not all the way through the outer part of the cap to prevent this from happening.
Not a perfect way to deal with the problem, but workable
The caps where as far as I know breathable (not one way). Is it a reproduction cap? maybe it's blocked or not designed to release pressure
Someone else may be able give a better method of repair than this.
Hope this problem gets fixed, not a good idea to have a pressurized tank inside the cab. A small leak in the top could pass a lot of fumes into the cab in a hurry.
Dave

winr · Post by **winr** » April 10, 2007, 8:02 pm

When I stop for gas and twist the cap I get a big "whoosh" of air also.

Richard.

MattsIASlickShop · Post by **MattsIASlickShop** » April 10, 2007, 10:32 pm

Just go to your local parts store and tell them you want a vented gas cap. they are cheap and will do the job. mmmm....new chrome.....

cdherman · Post by **cdherman** » April 10, 2007, 10:36 pm

AFAIK, the slicks tanks had the pressure build up from the beginning. I would NOT drill holes in the cap, as the gas sloshes around in there like crazy and you'll get gas running down the outside of the cab.

The pressure buildup is part of the reason that even a tiny leak in the cab makes for a smelly ride. (Ask me how I know...)

The later trucks had a vent that put the gas vapors into a charcoal bed that was somewhere (where??) and helped some, so far as I know. It was not a great system, and was aimed more at making the feds happy, then making the truck better.....

j-mac · Post by **j-mac** » April 11, 2007, 1:21 am

Thanks guys, I was wondering about this too. My truck has always reeked o gas and suspect it always will, but a few days ago gas started running down the cab and I noticed that a little piece of the gasket in the cap had broken off. I have to replace the rubber but I was wondering if it was the right kind of cap to begin with.

64slick · Post by **64slick** » April 11, 2007, 3:10 am

MattsIASlickShop wrote:Just go to your local parts store and tell them you want a vented gas cap. they are cheap and will do the job. mmmm....new chrome.....

the caps I've have found are vented but only to release the vacuum, not pressure, they only vent one way.