I am so confused. I was checking fuel pressure on my '91 NA. Pressures at idle seem normal per the fsm, but the pressure steps up when RPM is increased. This happens even with the vacuum hose to the fuel pressure regulator disconnected. I read that the ECU steps up voltage to the fuel pump (Ash's 6 P's describe this.), apparently as a function of engine RPM. But how does the pressure increase (regardless of pump flow) if there is a regulator that only knows about 1) supply pressure and 2) vacuum and should always maintain a constant delta-pressure between these? I would have to think that in this situation, the regulator is not doing what's it's supposed to do. Any explanations?
