Bob,

Checking pressures/flow rates may be next. I think I will ask a service tech to do that; I'm not equipped!

Turns out I'm a one-pump (Regina) kinda guy. Maybe the pump is operating sub-par; not well enough to supply constant line pressure?

Where is the check valve? Can only find what appears to be a small pressure-check fitting, unless that's really the check valve I'm looking at (appears to be like a rifle casing, brass, stuck in "T" formation in the rubber fuel line. About a foot aft of the fuel filter.

Relay operates properly, but I'm not here the "bzzt" I used to hear. Fuel pressure regulator can't be too bad, the car restarts fine all day long.

I'm stumped. Maybe the in-tank connection hose from pump to fuel line is lousy, and releases line back-pressure.