So after fighting a upper end tick/knock I figure it's time to start a build. Still unsure on the direction of the motor. Start with a short block or bite the bullet and get a crate long block? Anyways... I plan on ditching the SD efi and go with Fitech for a stand alone. Here's where it get complicated I plan on reusing the factory fuel system. I know I'll have to upgrade the high side pump to a 90psi 255gph but the main thing is wiring. From the diagrams I'm not sure if the EEC controls the pump or does the relay fire the pump by ignition on?

 

Pretty sure the PCM sends a signal to the relay which closes and sends power to the pump.

 

Info on the truck? I'm not exactly sure, but seeing as the pump goes through the priming stage before startup, the EEC would need to play some part. Once started, the pump stays on full and is regulated through the... well, regulator.

 

Yeah I think what happens is the PCM sends a 2 second signal to the relay for prime and then if and when the engine is running (or maybe just turning, not sure which) it sends a constant signal to the relay for running.
That's my best understanding of it - it's pretty close to what happens, I think.

 

THanks guys. I should of thought about that it primes so I'm fairly sure then that the ecu runs the pump. So with that being said does anyone think running the signal from the ecu to a switched ignition be a issue? I'm fairly good with electrical but always good to have other opinions

 

Not sure what you're planning; but the PCM runs at about 5 volts. Be careful about throwing 12 volts at it.

 

I'm removing the factory injection and replacing it with Fitech

 

Hey guys, can I jump in and ask a question here without being rude?