well i just bought a 1990 cherokee yesterday, i filled the tank up to full and it was leaking gas like crazy, so I backed up my driveway wich was a bad idea cause it leaked even more then it was when it was sitting level. So i drove up the driveway normally so the front of the jeep was higher then the back and the leaking stopped. I got under and looked at where the fuel pump goes in and it looked like it was leaking from the fuel lines that go to the gas tank, but it's actually coming from between the metal inlet lines and whatever is behind it. (hard to explain) Do i need to buy a new fuel pump?

 

Probably not. You DO need to siphon the fuel out (and don't use your mouth...buy one of those $14 cheapo siphons - they work fine) at least below half. If the tank is full, get fifteen gallons out to be safe.

Then you need to:

1. Put a fan directing air under the car.
2. Clean up around the retaining ring of the pump using a brass or bristle brush. Don't make sparks, obviously. Any dirt you leave will aggravate you when you replace the ring. Wear goggles/glasses and keep your mouth closed (ask me why).
3. Remove the retaining ring that holds the fuel pump in place, pop the fuel pump assembly off the tank and make sure the tank lip is clean. Don't pull the assembly out of the tank unless you're curious. If the car runs, the pump works and the pump assembly does not come out of there easily - you have to twist and turn a bit and there is a chance of damage if you're ham-fisted about it.
4. If memory serves, there is a rubber seal. Maybe not - I can't remember - but in any case the pump assembly needs to fit neatly in the tank opening. Then the lock ring needs to be put in place - this ain't easy, no matter how you do it. And it needs to be fully clockwise - like two inches of travel on that ring - to be properly tight.
4. Snug the hose clamps up. Replace the hoses if they are cracked or brittle. Might as well put in a new fuel filter.

You're done.