why isn't the fuel pump going in?!? HELP

so I have to replace my fuel pump because its only puttin out 15 psi when it should be 30 psi and I got my old one out fine with no problems. I got a rebuilt one from a yard out of a 90 cherokee (same year as mine) but the stupid thing wont fit!!! I spent 3 hours yesterday under my Jeep trying to get that stupid lock ring on and it still won't work. It seems like something is hitting inside the tank because it's not even lining up properly. I can't get the 2 tabs to go in there place because somethings hitting in the tank. I can't figure out what to do so thats where you guys come in hand.

any thoughts or special tricks im missing??

Blkxjkrawler said:

There is a little black rubber piece that fits on the end of the sender, and then sits in a cup in the bottom of the tank, The rubber piece likes to stick in the tank sometimes, make sure that you have that on the sender and that it is lining up in the cup. I fought this same way the first time I put a pump in a cherokee.

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ok that makes a lot of sense now because when I took my old pump out it didnt have that rubber piece on the sender and when I compared it to the new one I got I was wondering why it wasnt there? so should I just reach in the tank and see if I can pull the old rubber piece out?

yeah, it should pull right out, then you just have to make sure that you get it back into the cup with the sender, you'll know becuse the sender will kind of stop moving around and feel more solid becuase that piece is anchoring it, and the tabs on the outer part should line right up.