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I can't remember any fuel injected car that did not have different fuel pressures depending on load (manifold vacuum). Older cars (maybe still some newer ones) use a vacuum pressure regulator with a return loop for excess pump pressure.
Fords in the last few years use a sensor, without a return loop for fuel back to the tank.
The sensor sends a signal to the ECU which sends a specific amount of power to the fuel pump control module, which controls the pressure by controlling the pressure created by the fuel pump itself.
I am pretty sure my VX had the same system as Nissan from the same era. Wet pumps inside the tank itself with 65 PSI of pump developed pressure regulated to 30-40 PSI at the injectors, using engine vacuum. In turbo setups, the positive pressure would increase the fuel pressure beyond the point of atmospheric pressure.
It may be that recent developments eliminated the necessity to change fuel pressure, in much the same way some modern systems have eliminated the EGR valve.
regards
Mech
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