This is gonna sound stupid, but i cant get the fuel pump lock ring screwed back on my gas tank. I played w it for over a hour n it just wont go on. Has anyone ever experienced this? I got a 98 cherokee sport.

 

Not stupid at all. I think anyone who's done a fuel pump has this issue unless they re-use their old o-ring.

If you replaced the o-ring with a new one, it's most likely a lot thicker and that's making it tougher to get the lock ring on. I "sharpened" the tab edges of my lock ring so it would get underneath the tabs on the tank better. Before I did that, I couldn't get it on in more than 2 places.

 

here's a tip when using a new o-ring: Before installation sandwich it between two smooth surfaces (I use two sheets of clean stainless) and stack some weight on it (I use 50#) for a few hours (I use a min of 12, 24 is better) to compress the ring. Incline the lock surfaces (see 67 GMC post) so you get a 'lead' on the edge. Use a brass or aluminum drift when driving the lock ring (no sparks that way), and lots of o-ring lube (white lithium works fine). Patience & a steady hand are your friends.

 

X2. Good advice. I wish they just made a flat o-ring instead!

 

For specialty o rings such as flat, square, x profile and others, McMaster Carr is a great resource:
https://www.mcmaster.com/#o-rings/=16r0159