Fuel pressure inquiry

[Maj]

I would check the voltage at the pump,i think you may be loosing current at a bad connection like at the fuse or multi connectors or a relay
With the turbo i use an aftermarket pump , and the original fuel pump wire to trigger a new relay that has fused heavy wiring straight from the battery
and heavier fuel pump earth too direct to motor at the battery earth point, your fuel pump probably runs on 3 or so amps, mine uses 9