Fuel pressure in caprice ls1990

I like to see 'at least' 12 psi on a TBI unit!! .. I think specs call for 9 to 13 psi,... but it aint going to run 'right' with only 9 psi...!... Check for restricted fuel filter first thing if pressure is low!... Can pinch return line for testing... Do you know what i'm refering to??

Which engine and need the 8th digit on vin number.