Don't know why you would need a new tank? Fuel pump, sock, and filter are usually all you need.
Replacing fuel pump guide
(Note: 99-up Fuel Systems are returnless. there is only one quick disconnect on the sending unit to remove and the fuel pressure regulator is in the sending unit):
Dropping the tank requires a long 16mm for the front two bolts on the gas tank, a short 13mm, 8mm, 7mm, assorted sizes of quick disconnect tools, long extension, wobble, jack and patience. A second pair of hands is always welcome with this job.
Remove the spare. Lift the explorer and put it on jack stands as high as it will go so the tank will slide out, (put them under the frame just before the forward leaf spring perches so the axle will drop a little bit making it easier to get to the two lines on the rear of the tank.)
Remove the two filler hoses going to the rear of the tank. Loosen the hose clamps and work them off.
Put your jack under the rear of the tank to support it. Towards the middle of the tank there will be a plastic strap. it has a long 13mm bolt that is over the top of the driveshaft bolted to the frame. Use the wobble and long extension to remove it (if you want you can unbolt the driveshaft from the rear axle to get more clearance. You will need a 12 point 12mm deep socket).
(For this next step you might want to remove the driver's side rear wheel to be able to get enough clearance to get to the connections.)
Drop the tank a little bit so as to reach the plastic evap line (
DO NOT drop all the way, the plastic EVAP hose will break if stretched too far.) Remove the green evap line connector by squeezing the two tabs and pulling it off. Disconnect the electrical connector to the pump.
If you can reach the quick disconnects for the fuel lines remove them now, if you can't you can drop the tank a little more, just don't put any tension on the fuel lines. There will be a lot of fuel coming out of the lines so keeps some rags handy.
Lift the tank back up to its original position to take the strain off the two bolts on the front of the tank and remove them. Drop the tank again as far as it will go (you may have to slide it off the jack to get enough clearance) and slide backwards. (depending on how much fuel is in the tank a second pair of hands on the front of the tank may be required.)
Slide the tank off the jack once the front of the tank is on the ground if you haven't already. Move the tank to the passenger side to get it off the strap, then lift the strap out of the T-slot in the drivers side frame rail and slide it and the tank out from under the explorer.
Remove the 6 8mm screws holding the fuel pump sending unit in. Remember the orientation of the fuel lines! Carefully work the sending unit out of the tank, the fuel level float will not come out with some careful maneuvering so DON'T FORCE IT. Once out make sure the sock is still attached to the pump. If not, it's probably floating in the tank and you will need to fish it out.
Loosen the hose clamp holding the fuel line to the pump and remove the electrical connector from the pump. Use the 7mm socket to remove the bolt holding the pump retaining strap in place. Slide the pump out of the sending unit.
Install is the reverse of removal. Orient the sending unit as you took it out. Don't forget to install the evap line before lifting the tank all the way up. And push the tank up as far as it will go once done to get the strap bolted back in.
