hotrodK1500

Hello fellow Chevy gear heads and thank you in advance for your help! Also, I apologize for the novel.

Here is my situation and question: I am a proud owner of a 1990 k1500 stepside. At a respectable 240k miles, it gave up on life. Lost third and fourth in my 700r4 and threw a rod in the tbi 350. Before assumptions are made, I do not beat on this truck. It is used to haul a quad every now and then, with od off, but other than that it is nothing more than my daily. Anyway, my buddy has a lift and agreed to do a motor and 5 speed swap for me for a bit of cash and a case of beer. I picked up a good used crate motor with a lunati cam and edelbrock intake, and got a good nv3500 and pedal from a donor truck. Got everything installed and everything functions as it should, mostly. The issue I'm having is that the fuel pump (stock, but recently replaced in tank pump) primes but doesn't run once engine fires. I know this because I installed a Holley pressure regulator with psi gauge. It was my initial understanding that the ecm determines if the engine is running based upon readings from the oil pressure sending unit, which I reused and is sending readings to my gauge seemingly just fine. But then I read that the motor also uses the old ecm controlled ignition to also determine if engine is running. Which was replaced by an hei. So I believe that is the cause of my problem. I figure best bet at this point is to bypass the system in some manner with a keyed source. If I understand how the fuel pump relay works correctly, it has one side that is power in power out, with a "switch" in between. On the other side is an electro magnet that when supplied with power, pushes said switch closed, completing the circuit. Now, If this is the case, there should be 2 inputs on the magnet side coming from the ecm, one to prime the pump, another to run the pump. So theoretically, I can reroute the wire that comes from the ecm to run the pump to a keyed source, completely bypassing the ecm. Which as far as I can tell, should solve my problem while also retaining the stock fuse. Correct? I've read also that it is the green/white wire. Is this correct as well?

Thanks again!