hello, i'm trying to figure out why i have a hesitation problem from 1200-2000 RPM's(just installed a gm847cam)...i did a fuel pressure test and it read 45 psi KOEO...but when i had it KOER it would stay at 43psi but as i accelerate it would go to 38 psi...but with the vacuum line disconnected it would not drop in pressure as i accelerate....is this normal or if it's not what could cause this???...The car is also staying in closed loop(not sure why)...
Thank you

 

anyone?!?!?!?!

 

Your pressure should raise with the vacuum line off.
Have you replaced the fuel filter before? That's the most common issue. It also could be leaking injectors, bad regulator, leaking fuel supply line, weak fuel pump, or check valve.

As for the closed loop issue. You sure you don't mean it's staying in open loop?

 

the car starts up in open loop for a minimum of 30 seconds... it will turn to closed loop when the car gets to operating temperature. Ralls hit it on the money.