If the new seal won't accept the original filler neck, then that's at fault. I would try the heat gun and some grease and leave the neck installed to allow the seal to take a set, then reinstall it in the car. If it still won't work, re-use the original seal if you still gave it....

FWIW, I have a repop Taiwanese tank, original seal and filler. Took me about ten minutes to install...

 

I did mine a couple weeks ago.
Install the tank first then the neck with some grease to help it slide in.
Test fit outside the car to make sure they mate up first. It is a tight fit.

 

did the same thing last night,, put a little grease in the inside of the seal and a little on the filler neck,, it slid right in,, I did have to bend the pipe that is inside the tank a little,, mine was in the middle instead of near the top to go in the vent groove,,

 

I did mine a couple of weeks ago without a problem.

Polish the filler neck with emery cloth to remove any rust or rough places and grease the neck. If it still won't go in, then I think your new rubber filler neck seal is the wrong size / defective.

 

Yes it takes a bit of "coaxing" the neck goes in from the outside of the vehicle through the tail panel I recommend some, for lack of a better term, "sexual lubricant" on the filler neck, as well as a good application of same around seal. Seal must be installed and seated properly in tank first. With a little jiggling and thrusting it should all come together. This is obviously the most sexually oriented post on VMF to date. But results are results. Good Luck!!!

 

well i think i got it in, wasn't easy at all for me.

i couldn't find my old tank seal, which i think was bad anyway. the entire thing was coated in sealant.

I tried lubricating it, didn't help at all. the neck is pretty clean, as far as rust.

i tried the heat gun, i got that seal to the point of rubber smoking, and tried to jam the neck in, again it refused to go in no matter how much i tried.

then i ended up shaving the seal first with my dremel drum sander, then with a x-acto blade.

again the freaking thing just wouldn't go in.

i heated the seal up again with the heat gun, and used all my strength, and finally the thing slowly worked its way into the tank, back and forth, heating it over and over and eventually i was able to get the neck seated on the body and bolt it in.

urg.... i'm really not sure why i had this much trouble. i put a mark on the pipe and watched it seat deeper into the seal, I really hope the neck is in and i don't have a gas leak from the neck.

i must of worked for 4 hours on this stupid thing.
Its obvious the person that worked on the car before me had a similar problem since the neck was covered in sealant. the trunk floor in my car was replaced so maybe the alignment is messed up somehow. anyway got the new cork seal and the trunk floor seal in also. and put my mat back in.

 

Good morning
I have been trying unsucessfully too find one (new) but looks like all Mustang providers have the Gall Filler Tube or Neck till 1970, none of them for 1971 thru 1973. I have a 1973 Mach I and I need one urgently: Any suggestion?
Pedro Ruiz A.
phone: 6613314384Mail pruiz@prou.com