Don;

28PSI is correct.

Thad;

...and at that pressure, which is held even after you shut down (if eveything is right), vapor cannot form. And that may be a good place to start checking.

VERY CAREFULLY open a clamp on the fuel rail (observe fire precautions, watch for squirting fuel, wear eye protection), and temporarilly tee in a pressure gauge which you leave secured in the engine bay (I've done this with an oil gauge). This will allow you to check pressure during running and after shutting down (pressure should be held). Pressure regulator controls this, obviously. What is not so obvious is that regulator is of the dump type...that is, even with varying demand, pressure is regulated and excess coming from pump is "dumped" back to tank...this continuous flow cools fuelpump. Dump can be checked by opening line and allowing dump into a catch bucket. Regulators often fail because this dump function jams up...pressure then does screwy things and pump can make noises (pumping into basically deadhead).

Good Hunting