Bypassing Fuel Pressure Control Module For Return Fuel System
 

So I invested in a MSD fuel pump booster that I am ready to install but before I get to that I would like to clean up some shady wiring that a shop in Houston did while bypassing my fuel pressure control module. Would anyone happen to have a good wiring diagram and pinout for the FPCM? There is a bunch of loose wiring and crappy connections that I would like to redo. From the looks of it, it seems they just tapped into the positive wire going to the FPCM, ran that to a relay and then ran the positive from the relay to the pump and then grounded the pump to the chassis. Its dark but I'll try and get some pictures up tonight of what I am working with. This is a nnbs truck btw.

Ended up finding a FPCM pinout in my file of paperwork from the shop who did it. They used the Red/White positive battery voltage wire and the black ground wire going to the FPCM connector, cut them from the connector and ran them to a frame grounded relay. They cut the Grey fuel pump supply voltage wire running from the FPCM connector to the pump and connected it to the positive coming out of the relay. They cut the pink ignition source wire going to the FPCM connector and used that as the trigger for the fuel pump relay. Last but not least, there are two high speed GMLAN serial data bus wires (two positives and two negative) going to the FPCM that were removed, twisted and soldered together. One of the positives goes to one connector on the fuel pump hat and the other positive goes to the other connector on the sending unit hat. What those wires do, I have no clue. Anyone have any idea?

Did you ever figure this out?
I know its an old thread

I used the Fuel pump relay trigger (Green) from the ECM to a new relay for the fuel pump and just set HP tuners as FPCM not fitted. I also pulled the FPCM fuse and deleted the commination loss code.