So in going from TBI to carb, how would the electric in tank pump work? I understand that a regulator is needed to drop the fuel psi, but how would the pump still work properly? I heard it doesnt require the ecm, but what runs it? What causes it to prime? Rather lost on this matter, help!

 

12 volt switched and the fuel pump oil pressure safety switch on engine.

I'll try to word this simple so it's easy to understand.

You turn ign. on and for X seconds the pump will run with 0 oil pressure, with in X seconds if there is no oil pressure the pump stops receiving voltage and turns off.

You turn on ign. then start engine, the pressure switch sees you have oil pressure saying engine is running and everything is ok, so pump keeps getting voltage and keeps running.

The pump and the oil pressure switch is wired through a relay

 

So does the fuel pump work regardless of the ecm? Sounds like its an independant system working off of the ignition only. Is that accurate?

 

Yes correct, the fuel pump works regardless of the ECM.