Hold on a minute, I'd want a more definitive answer before dropping 2 grand on an ECU...
From what you said so far, it sounds to me like you have a bad connector on the wiring loom where it connects to the high pressure pump.
Disconnect the HP pump connector. With a DVM measure the voltage across the terminals in the loom connector, get someone to turn the ignition on but not try to start, during the prime sequence it should read 12V for about 2 or 3 seconds and then go to zero. Turn off the ignition. If you don't get 12V check the terminals for corrosion and check that one of them has zero ohms when measured to battery negative terminal.
Repeat this for the connector on the low pressure pump. I think this one will prove good as you achieved 9psi at the rail.
This should prove whether the HP connector is good or bad.
Both pumps have the same power source relay so if one pump gets 12v the ECU isn't at fault.
Clean the connectors with electrical contact cleaner and connect and dissconnect the connector multiple times and try the test again. If you are lucky it might just work!
