Fuel pump and refrigerator

[Kaz-7]

I want to know the mechanism of Caterham fuel pump.
My car is 2012 R300.
I put pressure sensor on the fuel rail and checked pressure.
It was about 4bar.
I think it is normally around 3bar.
Is it too high or this is normal on Caterham?

And how to control the pressure?
I want to know the mechanism of it.

Thank you.