Well it's starting to warm up here in sunny california, and when it does the gas in my tank, vaporizes and expands so that the pressure pushes fuel out the bottom of my tank. I can relieve pressure by cracking the gas cap (mr. obvious). THe gas cap in question is this new GM (http://www.yearone.com/serverfiles/part.asp?pid=8946N&c=0&e=0&cat=0&hid=014AB48351) unit from year one. Used to be fine with a stant cap, but then i lost my keys so i got one that didnt vent at all (mistake) and then bought this one hoping to solve my problems. I installed it the waneing summer so i didnt notice the problem too much at the time, every once in a while, though more likely when that tank was full. Now i was down to a quarter tank yesterday and started smelling it whil edriving, so i stopped and sure enough...drip....drip.....drip..crack the gas cap *woosh of pressure* everything is ok after that. What can i do about this? It makes me very nervous to fill up more than half a tank.... ok i've rambled on enough.... Thanks in advance

~Dan :confused:

Sounds like your gas tank vent tube isn't working would be my first guess.

You have a vented tank (tank vents are in the front of the tank - at least on a Chevelle Coupe). You would use the non vented cap with this set-up. There are probably 2 vent hoses going to a plastic vent fitting.

Dan,

Get used to it. My '68 does the same, except it comes out the vent tubes. I've now added about 8 feet of hose for the vents and a fuel filter and it STILL does it. I've tried a brand-new, stock non-vented cap, a Stant locking, vented cap, and recently drilled a hole in a non-vented cap just for fun. Still does it. I can drip gas on a 45 degree day with only a 1/4 tank of gas.

I'm out of ideas...

when I fill up in evening mine always starts gushing fuel out the vent tube the next day around noon (vented cap only dumped fuel out when going up a steep driveway).

The last time this happened, some guy who happened to see it said he installed a "roll-over" valve in a friends tank and it solved the problem. He said it is used by vircle track guys.

I have never seen one of these. If this only shuts off the port if the valve moves out of the vertical plane (like when you roll your car), this probably would not help. If it closes when liquid goes up the tube, though, it could might work.

Anyone had any experience with these?

GRN69CHV- I'm reasonably certain that Wagons/Elcaminos required the vented cap as the tank was under the dirvers side rear QP and not under the middle like the coupes, However, I could be wrong. The problem was worse when i used a non-vented cap.

Thanks for the insights so far everyone, keep em coming! graemlins/hurray.gif

71-2 wagons and elkies do have a venting system, like the coupe, only it is flat instead of going up into a vent can behind the rear seat like on the coupe.

Originally posted by 68Nomad:
GRN69CHV- I'm reasonably certain that Wagons/Elcaminos required the vented cap as the tank was under the dirvers side rear QP and not under the middle like the coupes, However, I could be wrong. The problem was worse when i used a non-vented cap.

Thanks for the insights so far everyone, keep em coming! graemlins/hurray.gif