thank you. In case anyone else needs this knowledge, I've got a car that won't start due to ignition issue, not fuel. I managed to get a copy of VIDA working with some real world sleuthing I determined: the car gives a shot of gas on entering key position 2, sometimes needle would hit 10psi, sometimes 20, hitting the release on the fuel pressure gauge with key in, PSI drops to zero (no demand like you said). With key in position 3 and starter motor turning engine over, needle bounces around at 55psi.There isn't really a spec for that, since the fuel system is demand-based. With the engine running the demand is zero, therefore the pressure is only what's residual.