2008 GMC Sierra Denali. returnless fuel system.

is the fuel pressure at the intake fuel rail schrader valve suppose to match the computers fuel pressure? I just hooked up my new gauge and it is reading lower than what my torque app is telling me. at idle, app says around 43psi while gauge reads around 36psi. I double-checked with a mechanical gauge and it also reads 36psi at idle while computer is telling me 43psi. is this normal?

 

The PCM reads the fuel psi at the FPR not the rail,
is seems like your app mite not be reading rite.
do you have a fuel problem ?
I use a Scan-Gauge II and it reads the same PSI
as my rail gauge does.

 

the app receives Bluetooth signal from a scanner plugged into the obd2. it reads accurate on everything else and should be accurate on fuel pressure also. I was just thinking that maybe pressure is different at the rail with a returnless system. but regardless of if they match, is 36psi while idling and cruising and 43.5psi at WOT normal intake fuel rail pressure for an nnbs?