Guess might have been overly simplified answer for the OPs purpose then?

As shown in the diagrams provided (nice diagrams by the way frederic) key "on" closes the EEC relay then that in turn powers the fuel pump relay closing it via the red wire, same wire also supplies power to the injectors along with whole host of other devices on that circuit, as well as the EEC/PCM whichever the case may be.

 

alright i guess i can tap into it there then.

the truck pinout only shows one 02 sensor for both speed density and maf is that correct? i know the mustang has 2.

 

i was just looking at the diagram and you are correct. lots of info and i really appreciate the help with that. the harness ive made mirrors the fuelinjection.com one almost exactly except the maf i made into a seperate harness with pins.

 

Nothing wrong with saying a switched source. I was just trying to make it less of a hunt for a good switched source under hood. It has been a while since I got into the engine wiring so it was almost as much of a reminder to me as it was to help DT 466Man.

 

Got everything put on thos evening. Finished up my wiring harness this afternoon. Turned the key on and everything lit up like it should. Fuel pump ran and cut off like normal. Check engine light came on amd went off. Got a couple connections to finish up and ill find out tmrw morning how its gonna work out.

 

And its running. My observations... Way better off the line and better throttle response. Revs quicker starts faster.

Now on to the cam/ heads swap