No power to fuel pump or injector

I'm not sure how the fuel gauge figures in with this but you will only have 12 volts to the injectors, ignition coil, and fuel pump for one second after turning on the ignition switch, then again during engine rotation, (cranking or running). You have to measure that voltage while a helper cranks the engine.

If there's no voltage for that first one second, you need to see if the automatic shutdown (ASD) relay is turning on. What I would suggest is removing the ASD relay, jump terminals 30 to 87, then take your time measuring the voltage again at the coil or any injector. You can do that without cranking the engine or even turning the ignition switch on. If there's still no voltage there, there is a blown fuse or some other wiring problem, possibly a corroded rivet between the metal strips under the fuse box.

If you DO have 12 volts now, the computer isn't turning the relay on. That would be very uncommon. Also, when checking that voltage for the first one second, you should do that with a test light, not a digital voltmeter. Most voltmeters don't respond fast enough to give an accurate reading.