2002 mustang gt no fuel pressure after new pump and filter

Make sure your didnt install your filter backwards. They are directional.

Turn the key on but do NOT crank. Does the fuel pump "prime" for a few seconds at each key on?

Did you replace the entire fuel pump basket or just the fuel pump? If you replaced just the fuel pump did you inspect the flexible line between the pump and tank hat for leaks?

A bad fuel rail pressure sensor (FRPS) is a "no start" sensor for the 1999-2004 model years. Inspect the FRPS connector for bent or pushed pins. Look for any evidence of corrosion. Double check that the intake vacuum reference line is connected and leak free. Inspect the vacuum line for evidence of raw gas.

Use a mechanic's stethoscope to listen to a fuel injector during cranking. Can you hear the "click" during motor cranking? I also recommend using a "noid" style test light to confirm power and PCM signal pulse at the injector.

Test for key on VREF 5 volt power at the FRPS between the BN/WH and GY/RD wires.

Beyond a doubt the easiest way to test for a possible bad FRPS is to use an ODB2 scanner to ask the PCM what it thinks the fuel pressure is. This also makes trouble shooting a bad sensor or wiring problem much easier.

Here's some more information that may be of help.

1996+ Crank with no start check list
https://www.allfordmustangs.com/forums/4-6l-tech/336452-1997-mustang-wont-ignite.html

ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/