You probably need the help of someone that has their 5.0L efi in a Stang.
I can tell you what happens in my Volvo install if you like. When I turn the key from off to the 'ignition on' position, my ecu provides ground to the fuel pump circuit for about 2-3 seconds, then, if it doesn't sense the car turning over, it shuts the fuel pump off. I believe it looks for output at the alternator to determine if the engine is turning over.
Yes, that will turn the pump on. When u do that its turning the metal pickup in the ignition pickup sensor, and turning on the pump, i figured this out when i was putting in my distributor with my key on and i was hearning like a "beep" noise(i dont think thats normal lol) and when i turned it the other way the pump went on for a second or two. So I made a thread about it and Jrichker or Hissin50 told me about it. Im sure if u do a search on it u would find it.
What ^^^^ he said, two conditions to activate the fuel pump...Ign. On (initial VPWR) for priming shot and PIP signal from ignition to ECM...if you check, you'll also hear the corresponding injector/spark plug firing also...do you have a problem with the pump at startup?...
No , no probem with pump a startup. It ust seems like it desnt want to start. I went through the fuel injeted checklist and found a few things. Moisture in the cap for one. I also pulled the plugs and manually cranked the engine, I had a **** load of fuel dump out of the plug hole. So, I blew out everything with the air gun and let the car sit with no plugs overnight. I also noticed that the battery didnt have full cranking power.
Im going to put a new set of plugs in it and make sure the timings on point. Also, Im going to put a jumper pack on it and try again....wish me luck!!!
Absent other info, and if you know your battery is up to par (even put a charger on it while cranking, etc), I would mark the dizzy position right now. Then loosen the hold down and turn the dizzy a little each direction while someone cranks the car (be aware you can get an ignition shock if you touch a spark plug wire or the coil wire). Slow cranking on non-EFI stuff used to suggest retarded timing, but I really dont know that this is an issue for EFI.
Sounds like what mine did when the TFI module took a crap, only I didn't pull plugs or anything, just had a "gut feeling" along with some great troubleshooting advice from other members here.
Mine didn't run the fuel pump when I turned the dizzy with the ignition on, it fired one of the injectors.