Fuel spilling out the gas cap

[RustyBlueTruck]

With more than 1/2 tank of gas my truck spills fuel out of the fill neck in right hand turns. Has anyone experienced this? Is there a quick fix? Or better cap? This is a stock tank on a 1972 C10. Thanks
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[Ironangel]

Make sure the cap is vented, and the rubber seal is intact. If the cap checks good, slow down those right turns!

[Swar]

Check the passenger's side of the tank, there should be a vent line that comes from the tank and goes up inside of the corner of the cab up to the roof, and returns back down and goes through the floor.
You need that to vent the tank, then you need a non-vented cap to keep the fuel from sloshing out.
Sounds crazy but that is the only real way to stop the problem.

[cdowns]

I had no problems for the many years that I ran a vented cap with a good rubber gasket stoped the fuel spill over on turns

[mike16]

I rely on the sloshing fuel sound to guestimate how much fuel is in the tank and if I can make it to the gas stattion.

[joecaruso]

I had this problem this past summer. A new gas cap solved the problem for me.

[jabos]

Where do you find a vented gas cap, I am on my third one and they are supposed to be vented but they don't work.

[57taskforce]

As said above I'd bet the cap is bad.

[custom10nut]

I've changed out numerous different caps. If it's vented it leaks, if non-vented, it caused vacuum lock. All it takes to leak is to fill up more than 15 gallons and an easy right turn, like an on ramp to the interstate. This condition is the main reason that I want ti get my tank out of the cab. Incidentally, right now a little gas doesn't do any damage (my paint is toast), but when I finally get it painted, it'll be a real issue, as I'll want to use the whole tank and not just 3/4. I don't remember having this problem with my dad's 68 GMC when I was younger.

[57taskforce]

If it's a 1/2 ton 72 more than likely it came with eec. If that emissions equipment is still there and functional you shouldn't need a vented cap. If it's not there you then you need the vented cap.