2000 GT not starting, just cranking

You need to check your fuel pressure!

You need to check to see how much fuel pressure you are getting at the fuel rail. Sounds like you are losing your fuel pressure very fast somewhere in the system, after you turn off your engine. May be the pressure regulator is leaking. The pressure in the line must be constant at a given psi when the ignition switch is on, propably between 36 to 40 psi. You will have to double check to make sure that is the correct pressure for your application. Put a gauge on your fuel rail and test for the required fuel pressure. There should be a schrader valve fitting on your fuel rail somewhere. Remove the schrader valve that is inside the fitting, install a fuel pressure gauge, then turn your ignition to the on position. Some fuel pressure gauges are able to screw onto the schrader valve fitting on your fuel rail. You may have to purchase after market fittings to install the pressure gauge onto your fuel rail depending on how your fuel rail was designed. The fuel pressure at the gauge should be constant, and should not drop with your ignition switch on. The fuel pressure should be at the required psi. If you don't have the required fuel pressure at that point, it's either your fuel pressure regulator or fuel pump, that is going bad. It is normal when you turn off the ignition switch, to see the pressure dropping after approximately 5 minutes. It should not drop fast. It should drop slowly at a given rate. I don't have the spec's for that rate. If the pressure drops fast after you turned off the ignition switch, say within a minute, that would indicate a leak somewhere. The valve looks just like the type that is in valve stem of your car tire. You will need the tire valve remover tool. Make sure that the portion of the tool that makes contact with the valve is long enough to reach the top of the valve, otherwise you won't be able to unscrew the valve. Some of the tools are short and won't reach the valve. Just look for the type that can go deep into the schrader valve fitting. Don't forget to re-install the valve when you are done. Hope this helps! Good luck, Tommy.