[Kevin Price]

Vacuum has nothing to do with your problem, it does have an effect under full throttle as it closes the regulator.

The computer does not know the fuel pump is on without the relay telling it it is on. Therefore, if your computer thinks your fuel pump is off it will not fire the injectors. So, your engine will crank all day, its just not going to be getting any fuel.

Your fuel pumps don't necessarily have to run through the relay, you just have to close the circuit so your computer thinks it is running through the relay. Get a relay from a mustang in salvage, trace the wiring from the computer to the relay and I bet you money she'll fire right up.