E  in Fuel ate glue I think . It will eat solvents too. Not sure what you could use on it that's e safe. 

My options were pour something in the tank or find a new tank.   It was much cheaper to pour in and try.   It sealed well   We made sure to coat the complete inside of tank, had some run out fuel spout hole, and out around top of filler neck.   We thought maybe it would peel but I do not remember any issues with debris or plugging of fuel line.   

That’s a great idea sealing it on the interior.  Aesthetically it would be much better provided you trust the product isn’t going to peel and plug fuel filters in the future.

I used a similar epoxy coating as below on a plastic dirtbike tank that leaked around mounting brackets.     It was in the late 80’s and it worked great.  Cleaned tank, Dumped the can in tank and swirled around and left to dry     

I’m guessing the black piece is factory glued in place.  Would be nice to pull it and re-glue, but not sure I can do so without destroying it.