My son dropped the fuel tank out of a 2000 grand Marquis and pulled the wires for the fuel pump and gage from the factory plug. I can cut and splice wires but I’m not sure what wire is what. Any suggestions?

If the new pump doesn't have a matching connector, it's the wrong pump. Return it and get the right one. You don't want to splice wires to the fuel pump because of voltage drop and corrosion.

I do not think this is a safe idea, the tank is plastic and if you drive through it you may cause a fire.

on top of the gas tank,once dropped everything will be in view,drop slowly support under tank as you are lowering it

All Fuel Pumps are inside the fuel tank

Have to drop the tank down & remove pump
from the top

Been that way for 25 years

First you have to diagnose the real problem
Can't assume the pump is bad

Voltage drop test the electrical circuit , do know how to do automotive electrical testing . Lose connection , resistance in the circuit , lose ground Mastering Voltage Drop Testing with Pete Meier and Jerry Truglia Testing Electric Fuel Pump Problems with Voltage Drop Test

The most common cause of this problem is that the gas gage sending unit that senses the fuel level is defective, it is an open circuit. The sending unit is part of the fuel pump module and all comes as one part. To replace the fuel pump module you must drop the fuel tank out of the truck.

yes

Some things to check:
Does it have fuel getting to the engine ? (fuel pump is located in gas tank: check fuses)
Does it start if you spray some starting fluid into the air intake? Is there any spark when it is cranking over ?
A 2000 model? Might be old enough for a corroded power wire splice point. Might just be a bad computer.
Start by checking the fuses.

2003 Grand Am GT,You have to drop the fuel tank,remove heat shield,remove all lines,electrical plug ins,then you are ready to do straps,be sure to go get extra nut and bolts for straps (2) of them had to cut off old ones,once straps are off depending on how much gas is in the tank used jack to lower tank,fuel pump was a twist off with locking mechanisms on top of tank,used a rubber malet and screw driver to loosen,pull out after diconnecting plug ins etc,replace blue plug in for harness to fit new pump,was recommended since it could corrode,lifted tank back up connected wires,lines etc,put key in on position 3-4 times for pump to pump,car started 1st time,my first fuel pump took my son and I 2 1/2 hours,new pump $250.00 wire harness $15.00 and two new nuts and bolts $3.25

you can try just resetting the fuel pump switch located in the car

the switch is originally in the car for in case of an accident, however, if changed, chances are you also have to reset it

in my 98 grand marquis, the switch is on the left side of the trunk