I am not fully sure but I don't think there will be much pressure when engine cold. I assume when the cams spin the pressure builds up (could be wrong).
I still have in my head and I think it was here, if regulator gone it will cut out. If pump has failed it will go into limp mode.
When my EML is on the car does not like starting in cold. I got in the other day turned it on when finished work, 4 hours of being off and straight into limp mode. When I restart I get spanner come on.
When we ran the codes it was saying about oxygen sensor. It works fine but I think the misfire is affecting other things.
I have managed to drive steady and EML has now gone. It runs better with no fault showing but I can't take it over 3k.
I am borrowing money to get a pump this weekend as it's doing my nut. If cured, brill, if not I can sell the old pump after stripping it.
The only other issues for misfire are injectors which should give a code and leaks mainly around throttle body.