The fuel pump is making noise and I figured one (very good?) way to investigate would be fuel pressure measurement. I can find 2 places on the car where there is a small bike-like valve (presumably for this very purpose):
a) underneath the fuel rail at the front (it's hidden and you have to crane around to notice it)
b) close to the main fuel pump underneath the car

According to the FAQs and other posts here, I'm expecting to see a steady 44psi at a) (right?) However -- what should I see at b) if the system is working correctly? I think b) is placed between the pre-pump and the main pump so I am presuming that Volvo put this here to enable a convenient way to check the pre-pump.

Can anyone comment on how I can use these valves to check the system?

Thanks,


Rob