XR8 Fuel pump/regulator issues

[pete r]

G’day blokes, this is a follow on from the idle hunt issue I’ve been chasing…

It’s a 98 XR8 and in the Key On Engine Off position the fuel pump isn’t switching on. Dash lights on but no fuel pressure, Forscan shows the fuel pump is off.
However crank the engine and the fuel turns on and engine starts!

Another weirdo thing, I measured the fuel pressure with engine running and vacuum line connected to the regulator, the gauge showed 32psi. I gave it a rev and the pressure didn’t increase.

So I disconnected and plugged the vacuum line, started the car and the fuel pressure came up to 42psi. “Seems about right” I say to myself.

I connected the vacuum line back up, started the car and the fuel pressure measures 32psi, but now when I give it a rev the pressure flicks up to 42psi then back down again.

There is no fuel in the vacuum line so the regulator diaphragm seems ok.

First things first, does anybody have any idea why the pump wouldn’t be running in KOEO mode?