Gas tank does not stop hissing after taking off gas cap

Just like the title says. I noticed I was smelling gas ever since I filled a few days ago. I went to see if maybe I forgot to put the gas cap on there and realized I haven’t. I decided to take the gas cap off and there was a ton of pressure buildup. I kept it off and waited for the hissing to stop…but it’s not stopping. Left it off for 5 minutes now and there’s still a hissing sound.

I’m confused and not sure what to think of it. And ideas?

Are you sure it’s hissing from the fuel door area or from your engine? Do you still smell gasoline?

Pressure release is normal, but it definitely shouldn’t last more than a couple seconds. I don’t think there’s any way that the gas tank could be building enough vacuum to continue that noise so likely what you’re hearing is something else. Without hearing it in person it’s really tough to guess at what it could be.