Whats is the ideal fuel pressure for an LT1 while ON, running, and should there be an increase while revving, or high idle?

 

Normal range is 41-47 psi with the vacuum hose off of the regulator. Same for WOT (with hose on). Idle pressure (with vacuum hose to regulator on) will be lower, maybe as much as 6-8 psi.

Pressure is controlled by the regulator. Low vacuum=higher fuel pressure. High vacuum=lower fuel pressure. When you rev from idle, vacuum goes lower, pressure should go up.

 

I tested my fuel pressure tonight and while in the ON position, I read a 40 and while running, a 39. While revving the motor, i ranged from 38 to 41. Bad? Im not too sure what you were talking about as far as vaccume lines. Which lines are these? Am I supposed to disconnect any while testing fuel pressure? Also, if my readings are bad, could they be causing this problem?
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Shoebox, thanks for repling, you give great feedback!

 

Shoebox gave you the exact answer. Engine idling - Remove the vacuum compensation line from the fuel pressure regulator (plug the line). Fuel pressure should be in the rang. of 41-47psi (the injectors are flow rated at 43.5psi). Reconnect the vacuum line to the fuel pressure regulator. Pressure should drop in proportion to intake manifold vacuum. With a stock cam, thats about 6-8psi below what you measured without the vacuum line.

Then drive the car to max rpm/load and the fuel pressure should hold withing 1 or 2psi of the value you measured at idle, without the vacuum line.

Every time you move the throttle blades, intake manifold vacuum changes, so the fuel pressure is going to change. Open the blades, intake manifold vacuum drops, fuel pressure rises. The purpose of the vacuum compensation line is to keep the difference between the fuel rail pressure and the intake manifold at exactly 43.5psi.

 

Regulator and vacuum hose. Nothing sounds bad to me in the way you have tested, so far.