How to limit fuel pressure when electric fuel pump is on?

I’m trying to limit the maximum fuel pressure value to 4 PSI when the electric fuel pump switch is on but even if I set the flight_model.cfg parameter max_pressure_auto_pump=4 when the switch is on the fuel pressure always goes to the maximum value set using fuel_press_max=1044 psf (7.25 psi)

I’m using the old FUEL system as defined in the flight_model.cfg file

It seems the value entered in max_pressure_auto_pump is not considered by the sim