So, I decided to swap out the old tank with a semi new one from the JY. Did some rustproofing and cleaning today and when I gave it good shake a smallish rubber thing shook loose and fell out. It is cone shaped and about an inch tall. Tried looking for a pic (didn't have a camera) but couldn't google one.
Does anyone know where this thing goes? I'm guessing it is a valve seal of some sorts?

 

Pictures are good. But you didn't even tell us anything about your jeep. My guess is its the float off the sending unit if you have an early to mid 90's but that is just a guess.

 

Sorry about that, it's a 94 XJ 4.0. Will take a pic today when i'm at the work shop.

 

Its the rubber isolator for the metal return tube on the fuel pump. The "cone" rests in the bracket in the tank on the bottom. If you look thru the pump-hole, you will see a smallish metal bracket on the bottom of the tank.

This makes installing the pump a bear sometimes. You need to hit the hole in the bracket with the rubber cone on the pump assy to get the pump to line up right.

I just replaced my tank and the junkyard one had the rubber cone rolling around in it too. I noticed my pump had one on the return tube and figured it out.


Found some Pics of it.. Hope this helps..

First one..




Second one..

 

Wow, great post! Thank you! I'm glad I don't have to put it on again somewhere in the tank.

 

!! My bad I had the wrong piece in mind.