Can you repair a 1998 f150 fuel module - 1998 Ford F150 Truck Fuel Pump & Sending Unit Module for V8 5.4L 2W

You may be able to repair it depending on what the issue is but considering the level of difficulty associated with removing the fuel line fittings and gas tank I would suggest replacing the unit. It would be very unfortunate to make a tinker type repair only to have to pull the whole mess out again a short time later.
When you decide to remove the tank go under the vehicle (all safety considerations apply. Disconnect the negative battery cable, apply the parking brake, block the wheels...) with a wire brush and some penetrating type fluid. Brush off any dirt / debris you can see on the fasteners / tank straps / etc. and spray the fasteners with the penetrating fluid....this will save you untold amounts of grief. Do this the day before you decide to pull the tank in order for the fluid to work into the threads, spray them down two or three times leaving it set a couple hours between spray downs.
Remember to wear safety goggles and some type of disposable gloves when you're under there.
Keep a fire extinguisher close to hand...gasoline is very unforgiving.