Strange bubbling sound from Gas Tank - 1970 B-Body

Hi All,
I was wondering if anyone might know what this might be...

I had my '70 Super Bee out on a fairly warm day last week. I added a few gallons of 91 premium to it (bringing to about 1/2 full) and drove around a bit. When I pulled back into my garage and shut off the motor, I could hear a very noticeable "gurgling" or maybe bubbling sound coming from the gas tank area. It was a sound similar to what you hear when your radiator is about to boil over.

Anyhow, after maybe a minute or less, I hear liquid running out on to the garage floor and sure enough there is a small puddle of fuel.

I crawled under the tank (by now it had stopped running out) and the only place I could tell where it MAY be coming from what this small outlet line (in the photo). Anyone know why this line is there? I suspect it's a vent line of some type, but should gas come out of it?

At this point, I could still hear the bubbling sound in the tank. I removed the gas cap and the sound went away completely. Put the cap back on and the sound came back.

This has never happened before in the years I've owned the car.... Any ideas? I'm especically curious if it's normal that gas can "boil over" and come out the vent tube like that??

Thanks a lot !

That vent line sould not be open like that. I would get a service manuel for your year model and put the vent system back stock.

Gas should never drip on the floor for sure.

Ok, thanks for the info on that.

Does anyone with a 1970 B-Body have a picture or know where this vent line should go to? I checked my factory service manual, but don't see a photo which matches mine. I imagine it's a rubber hose that connects here.. but to where?

Thanks a lot guys!!

My 68 road runner has a vent that's open just like that. It also has one that goes up into the trunk and comes across to the passenger side frame rail. Don't know what your gurgling sound could be. I could understand it stopping when you remove the gas cap but starting back when you put it back on?

I experienced the exact same thing just two weeks ago,except for the gas spilling onto the floor.
I crawled under the car and could hear it coming from the gas tank,and when I removed the gas cap it was quieted instantly.
I don't know why it did this????

Quote:

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I experienced the exact same thing just two weeks ago,except for the gas spilling onto the floor.
I crawled under the car and could hear it coming from the gas tank,and when I removed the gas cap it was quieted instantly.
I don't know why it did this????

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I think it is the fact that the gas is coming out of the ground cool at about 60 degrees and putting it in your 90 degree gas tanks and is expanding. That's why vent/vapor lines are important not to do away with. Plus the heat radiating off the hot asphalt heats up the gas in your tank.