I'm trying to strip the back down to bare metal to get a handle on some rust issues, this is glued to the metal under the carpet. Any idea on what it is or the best way to remove it?

 

Recently had all my interior removed and didn't see any of that. Try a putty knife?

 

If you're already going to strip it down, you could try a lil' bit of acetone with a putty knife, like EZEARL mentioned.

 

Its a sound deadener. If its anything like what i found on the Mustang, its a tar like substance (it turns rock hard once it cures) that requires heat and a putty knife to remove. IF its the same stuff. A real PITA to remove, too. It was also flammable, IIRC. No clue what Jeep used.

 

Soften it with a heat gun and scrape it off with a putty knife. It's for sound deadening.

 

Set my minions to work and we got it out. Then put a wire wheel on my angle grinder and finished the job.

 

looks like it was used to stop fumes from coming in for fuel pump acess hole thats been added...

 

It's not a fume barrier. Back before my dad sold it to me, he cut that hole to make it easier to replace that fuel line when the squirrels would chew on it. I think after the sixth or seventh time, he just replaced it with a flexible steel one instead of a plastic one. It was the before the hole.

 

that stuff is a NIGHTMARE to remove when i had to replace my floor pans. Its a tar like substance and took forever to get off i never found a good way to remove it honestly.

 

Apparently dry ice is the way to go with factory sound deadener. You can chip it off in chunks once it's frozen.