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No your pumps should not run continuously. The main pump noise could just be a noisy main pump or it could be a pre-pump that is either not working or, more oftenly, cavitating and sending air bubbles through the main pump.
Your pressure reg check, albeit rudimentary, is basically right on. Without access to a set of fuel pressure guages there is not a great deal more that you can check.
"Do all 740T work like this? or does the main pump shut off once primed and up to pressure like other cars? and so no noise can be heard at all?"
Main pumps do not shut off unless they are turned off. How your system works depends upon what year model you have. The earlier models do not run the pumps unless they see a speed signal whereas the later ones will buzz the pumps once when the key is cycled and then run them when an engine speed signal is present.
That relay is a pretty involved deal. Suffice it to say that it is the relays job to hot up the fuel pumps, mass air flow , the LH ECU, IAC, and the HO2S among other things. It will power up some of this stuff by simply turning the key on and some of it is dependent upon the engine speed signal to trigger the ECU to ground the appropraite coil in the relay.
Hope it helps,
Mark
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