There should normally be a strong flow on the return side when the injectors
are connected because the regulator is a shunt regulator; it dumps the
excess fuel from the pump back into the tank to control the pressure. I
don't know why you have no output on the rail side, though. If you are
saying that with both open there is no rail output it sounds like a bad
regulator... but in truth I've never tried that test. It just isn't the
usual regulator failure mode. At least you know the fuel pump is working :-)

Also... have you ruled out the ignition system as the culprit? The easiest
way is to fire a burst of starting fluid into the air cleaner box, closing
it up and trying to start the engine. If it goes "vroom" and dies then you
have confirmed it will run if the fuel is fixed.

Mike