Need Help setting Fuel Pressure on EFI

[91StangLX]

OK which is the correct way to set Fuel Pressure on an EFI engine. I was always told to disconnect the Vacuum line and set the regulator to 40 PSI then put the vacuum line back on and it should drop to about 32 PSI.

I have also been told to set the fuel pressure with the key on engine off and set the pressure to 35psi-45psi.

Which is the correct way and what should the pressure be running at idle.

 

[ss93cobra]

I've done it both methods and either way has worked for me. Disconnect vac. line and set it to 38-40lbs and then it should register around 32-35 with vac. line installed.