Thanks for the lesson. I'm still learning this stuff, and there's maybe no better car to learn on than one that's always broken!
SO I can tell you that I dead-headed the line and the pressure continued to decrease until it stalled. Opening the throttle brought it up a bit, but it never reached 36psi even under WOT. However, the fuel pressure being reported is generally so low that I don't have much opportunity to do any extended tests. I'll go through this battery of tests again later this evening though, just to confirm.
I should mention the problem has been getting worse. A few weeks ago the car would run reliably for a while, with intermittent hard starts or stalls at idle. Lately I can barely keep it running for more than a few seconds.
As for the electrical test, I was really just ensuring there was power making it to the pump. I've read MANY instances of a bad ground or power connection being the culprit.
And at least I know my injectors aren't leaking - it's held 20psi for 2 days now, according to the gauge.
Haha, thank goodness for small victories---at least the system holds residual fuel pressure!
OK, so you are sure that the fuel pump is getting full battery voltage, even as the engine is stumbling and ready to stall? That will be a key factor in determining whether the issue is with the pump itself or it is an electrical issue. This could be tricky to determine just as the engine is dying, because the airflow meter flap will be moving back and forth as the engine stumbles, possibly to the point where the airflow contact switch within the AFM will open momentarily. If this occurs and the engine stalls and won't restart, simply open the airflow meter flap manually with the ignition switched on and check if the fuel pump is getting full voltage.
I assume that you have checked the inertia switch in the engine compartment? This is extremely easy to check, as you can bypass it by simply shorting the two wires together.
If the electrical supply is OK, try to perform the fuel pressure tests previously outlined, and hopefully you will find the culprit! This must be very frustrating----I do this for a living (on Porsches and BMWs, not Alfas) and I know what it is like to stare into a black hole and be out of ideas. Keep at it and hopefully you will be able to track down the issue and then drive and enjoy your GTV6!