I have a drive by cable 5.3, factory harness striped down based on info from lt1swap. Vats and emissions cleared. Here’s where I’m at, I have spark. My in tank walbro fuel pump primes for two seconds, but then I don’t hear it running. If I jump the relay it will run constant but still no fuel at rails. I cracked open the return line on my corvette regulator and fuel comes out, but not on the engine side. Could the regulator not grounding or being bad out of the box cause it not to open and allow fuel to the rails.