Hi, can anyone tell me what my fuel pressure should be on a 75 280z? I am reading it at the cold start injector, with the engine off and pump running(in start with starter wire pulled) also with the car running at various speeds. Thanks Zedaffair

 

Should be 36.3 psi, relative to the intake manifold vacuum, according to the FSM. So, if nothing is running it should be just that. The fuel pressure regulators are known not to be nearly as reliable as the rest of the car, but being more than a few pounds off would be a problem. Replacing with an aftermarket rising rate regulator is a popular "while-you're-at-it" upgrade, but isn't super cheap (think they're like $230 or something new from MSA, for example).
good luck,
Dave

 

Thanks for the reply Dave, I am running about 40psi with out the engine running and about 36 psi with it running at idle. Does this sound about right?

 

Sounds about right, to very slightly high. When the fuel pressure regulator goes bad, it tends to not hold pressure at all rather than "sticking", so you're in good shape. Are you just checking out the system, or is it showing symptoms of something wrong?
Dave