Fuel Pressure Testing..
 

what should the fuel pressure be at idle at schroeder valve? 93 Z28 with stock injectors.

On my 97 at idle the manual says it should be at 37-38 psi. Before starting it with the key in on position and pump on it should be between 41-47 psi. It may be different for a 93, not sure though. I would pick up a Haynes or similar manual for your car.

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93 has different injectors than 97 right? does this make a difference?

I beleive the 93's use 22lb/hr injectors, I know the 94-97 uses 24's. I would think the fuel pressure may be different while running but not sure, probably the same with just the key on. Your model year was unique for a lot of things though, best to get the manual for it, and they are only like $15-20.