Gas bubbling out of fuel tank. Why 2 vents? Can I cap one?

Thanks Trace! Oh well, I have an idea but I'm too embarrassed to tell. I'll post it if it works. It doesn't involve any cutting or plugging up vent lines. Easy on, easy off. I think the vent line piping inside the tank must be rotted or somehow got a hole near the exit allowing it to puke. Can't fix that. I really don't want to spend hundreds of dollars for a new tank, so now I have to mickey mouse the vent and hope it works.

I just remembered the trunk vent line was rotted and fuel was puking into the trunk, so 10 years ago, I used that line and installed a return line to a fuel vapor filter (see pic). Sorry, I forgot all about it. It cured my vapor lock, plus car runs overall better. However, tank was puking from both vent lines before I made this change. Sorry for the confusion.
Last edited:
Without that vent(s) being capped or connected to anything, it's going to boil out, especially above half a tank, because that's when the fuel hits the vent.

If you're not going to connect them to the venting canister, you can cap them off with rubber nipples, and use a vented cap. Been running my California 4-vent tank this way now for over 10 years. On a really hot day, it is necessary to open the cap and let it vent after a drive.
Thanks Snotty! I bought a vented cap (delivery Friday) and will try it out. I installed my fix a couple days ago. Its been around 90F in Cleveland and so far its working great, but will it last? The filter stops the spitting of fuel while air has plenty of room to escape. (I drilled a couple small holes thru center top of filter inside the housing just in case filter clogs up). So far I noticed it fills up only 1/6 then drains back into tank within a few minutes. Its secured by a couple of clamps so it won't move around.

I know it looks cartoonish, but hey, it works. Anyone see any dangers or problems doing this? I'm not an auto engineer so thanks for all the help guys!
I like your cartoonish fix, and can't think of any reason for problems, infernos, immolation, etc. But what are we looking at? Is it just a fuel filter, or is it a filter/separator that you've installed "backwards" such that the two vents are up top like this?

Oddly, my issue is more about the "long" line up into the trunk and back out to the frame rail, although both lines will puke in hot weather while idling and pump exhaust heat to the tank. Anyway, congrats on your fix!!
Its just a fuel filter I had laying around. I'm hoping it'll work forever since I'll probably forget I even did this.
Its just a fuel filter I had laying around. I'm hoping it'll work forever since I'll probably forget I even did this.

I'm going to think about your fix. I might do BOTH vents, with the two filters side-by-side, up high at the crossmember and see if that works as a fuel-vapor separator. :thumbsup:
Hey Snotty, Where did you get your vented gas cap? The one (in middle of pic) I ordered doesn't fit and can't find one. The non-vented cap (on right) is deeper and fits. Can you post a pic of the inside of your cap?

I found out these vented caps are one way valves. They only let air into the tank and don't let gas or air out. So I'm thinking of making hold down tabs and drilling a couple holes in non vented cap and install the rubber seal and yellow valve over the holes (see pic 2).....But I'd rather just buy a vented gas cap that fits. Thanks.

Last edited:
Mine looks like the bottom one.

You can drill a 1/16 hole into the cap at the top. It will work as a vent.
Thanks Snotty. Do you remember where you bought it?

The one vent I already have is working good, so the vent cap is just a backup precaution. I'm going to run the one I made in pic below and see if it works. It only lets air in just like OEM. I'm guessing (hoping) the engineers at Chrysler designed the one way valve to blow out and let air out before the gas tank explodes.
Been so long ago, no. But it may have been through Atlas Obsolete, but I don't even know if he still exists or not.