to replace fuel pump on 2004 crown vic do i have to drop the tank or is there ac

FIRST make sure there is battery voltage at that switch in the trunk! If it is then drop the tank and replace the pump. If no voltage there, find out why!

There are some jobs IMO that are best left to a pro and dealing with fuel pumps and tanks is one of them. Even they sometimes have accidents that can lead to serious injuries and extensive property damage. Simke things like a drop light with an incandescent bulb can be a source of ignition if liquid fuel hits that hot bulb, or if the light falls and breaks the bulb.