Let's see on the '98, a general overview,
You'll first want to jack the rear of the car up (chock the front wheels/observe all safety precautions!) and support it with jackstands. Assuming the fuel tank is nearly empty, or the gas has been siphoned out (run the car until the "Low Fuel" light comes on or less than 1/4 tank), relieve the fuel system from the valve on the fuel rails under the hood.
Use the jack and a block of wood (or something else that will help evenly distribute weight) to support the gas tank. Towards the front of the car there will be two bolts (I think they are ~10mm) holding the gas tank straps. Unbolt them. Unbolt the fuel filler pipe and tubes from the car, the three ~8 mm bolts inside the gas cap (one will hold the gas cap on). Unbolt the 8mm bolt that helps guide the fuel filler pipe into the gas tank.
Slowly lower the gas tank, and make sure all tubes and connections lower easily, and disconnect as needed. When the gas tank is low enough you will see a circular plate on top towards the center. Should be another eight (8) ~8mm bolts that hold the plate on, and a few open wires. I had to get a crowbar to separate the plate, gasket and gas tank from each other since they were that tight. You will also need a new gasket. The fuel tank will be inside the gas tank, disconnect, unbolt and replace. Installation is the reverse.
REMEMBER to prime the fuel system by cycling the ignition from "Off" to "On/Ignition" a few times before starting the car. Do not start the car right away, you'll hear the fuel pump prime when the car turns on (not started). All this after you install the new fuel pump.
You might want a second hand around just in case. My fuel tank also held in place after I removed the straps, so you may have to loosen it. My fuel tank and fuel cover shifted so I had to get my whole body under to help prop it up. A second person can help if this happens.
Just take precautions. Don't smoke because of open flammable vapors, and remember you may be inhaling a lot of gas fumes. Be patient too, start early and do the prep work.
Again, just an overview of what's about to happen, a Hayne's or shop manual will have a much better set of instructions on what to do.
Originally Posted by MetallicMist
OsirisGuy is correct
Originally Posted by stangaroo
OsirisGuy is right
2002 Mustang GT
BBK CAI - Flowmaster Catbacks - Pro 5.0 Shifter