You need to get the fuel pump to run. The FASS pumps are usually wired with an external relay. Need to see how its wired. If nothing else run power and ground direct to the pump and see what it does. Its possible the driver in the ECM has failed. I would find a better mechanic.
Agreed , I have a 2000 that I relocated the lift pump rearward and just extended the wires to new location, eventually the lift pump stopped working so I just wired a relay to a key on source and added my own relay. I put tens of thousands of miles on it like that , never touched the ECM .
Find a new mechanic ...
