Gas cap problem!!

[volksworld]

you pump cool fuel out of an underground tank and top off your vehicle and let it sit in the sun on a 90 degree day and it expands a lot...way back when it was common to see stuff puking gas on the ground....so you quickly learned not to top off in hot weather...fortunately we were too broke to fill the tank anyway

[firstgencamaros]

Originally Posted by Mr Chevorlet

To modify the cap, the little taps that hold the check valve together, bend the tabs back and remove the plastic housing and you can cut the spring for lower pressure relief then put it back together and bend the taps over. Just a suggestion do it at your own risk.

I picked up a new cap from my local O'reilly auto parts. Masterpro part number 6023. I did the modification as described above. Cut the big spring for pressure relief almost in half. Did not mess with the spring on the vacuum relief. Out of the box it allowed the tank to build so much pressure that it would flood the carburetor when parked. After the modification the tank no longer over pressurizes. This is on a 1968 suburban. No charcoal canister on this model. I'm in AZ and it was parked outside in the sun when it was 108 the other day. When you would unscrew the cap it had so much pressure it about blew it out of my hand. This simple mod took care of the problem. As stated before. Do it at your own risk.

[hamjet]

I bought a chrome one at a local parts place,( I think Advance Auto) and I can suck air through it easily and still blow air with effort so it does vent in both directions, just not as easy outwards...

[chopnchaneled]

What hamjet said, Except don't try it after its been installed and had gas sloshing on it.
YUK!