So I got my car running and I hooked up my fuel pressure gauge and noticed that the pressure drops to about 30psi under WOT, BUT at idle and part throttle it holds 40-41 psi AND if I disconnect the vacuum line it shouts up to 45 at idle and will hold it at WOT all day long. SO my question is can I get away with just plugging the vacuum line or will it eventually destroy the FPR or should I just suck it up and get a after market adj.FPR or is the pump just not pushing enough volume? I wouldnt think the pump was the problem simply because it holds 40+ at WOT when the vacuum line is disconnected, I also have no idea whats in there for a pump (never had it out).

Mods are Ported lt4 heads and intake with 42lb injectors (yeah I know there a little big) cc306 and 58mm TB, LT headers, BLAH BLAH BLAH.

 

Something wrong. Its intake vacuum that pulls down the fuel pressure, and at WOT, there should be little vacuum in the intake manifold. There is no way you are pulling a full vacuum (45 - ~30 = 14.7psi) at WOT.

Removing the vacuum line defeats the purpose of the vacuum compensated fuel pressure regulator, which is to maintain a constant DIFFERENTIAL pressure between the fuel rail (positive pressure), and the intake manifold (negative pressure, referenced to atmosphere). Its not there to maintain a constant pressure on the rail. Fuel flow through the injector is driven by the DIFFERENCE in pressure between the rail and the manifold, and is proportional to the square root of the DIFFERENCE.

 

I would suspect either a vacuum leak somewhere or a bad injector.