Where is the Fuel Filter located?

There is only the filter that it part of the pump in the tank. What does the scan tool show the pressure sensor on the pump is indicating the pressure as? I suspect the issue is with the wiring or with the fuel pump control module not reading the signal correctly. What you can do is test the sensor at the pump. It has 3 terminals Pin one is a 5 volt supply from the control module. Pin 3 is a ground also through the module. Pin 2 is the signal to the module. It reads higher voltage as the pressure increases. With the key off the signal should be zero, then it is a linear increase as the pressure rises. at 8 PSI it would be .3 volts, at 87 psi it is 2.6 volts and at full pressure it will be 4.9 volts. The control module is also right there with the pump under the seat. The attached shows the connector and the powers and grounds. It is somewhat common for the connectors to corrode and cause problems. As the low-pressure pump is getting power (car wouldn't even run if it wasn't) the 12 volts and the ground are likely fine, however the pressure sensor 5 volts may be gone, or the CAN pins may be corroded. I would probably find a used module and use it to test the system using a scan tool to adjust the pressure output as you monitor the pressure.