fuel pressure regulator

[MrBtchy]

I've done a search on this and haven't found the answer.
I don't have any vacuum to the regulator and i know that it's not blocked. so i took my spare throttle body apart to see how it works. now as far as i can tell since the vacuum would be taken above the butterfly i wont get any vacuum till i apply throttle(just like the vacuum advance)! Problem is i still don't get any vacuum when the throttle is open....so does the regulator work on vacuum(or lack of) to work or does pressure build up do it?

[coop1er]

The regulator only needs to see positive pressure (ie. boost) to work
correctly.

[MrBtchy]

thank god for that, from all the hearsay i heard i thought i was probably leaning out under boost!

[TD05]

The regulator only needs to see positive pressure (ie. boost) to work
correctly.

that'd mean the regulator is returning fuel all the time and closes when positive pressure is sensed?? ...

[pajeroturbo]

yes my friends the regulator on the starion works only when your car goes on boost. at idle and vacum you must have a fuel pressure about 3 bar and when you go on boost it goes about 3,5 thats it.

[mrb1]

The regulator only needs to see positive pressure (ie. boost) to work
correctly.

that'd mean the regulator is returning fuel all the time and closes when positive pressure is sensed?? ...

No it just maintains the same actual fuel pressure across the injectors. It is always bypassing fuel.
no boost = 3 bar + 0 bar = 3 bar fuel pressure

1 bar boost = 3 bar + 1 bar = 4 bar fuel pressure but injector only see's 3 bar.
This is because the injector has 4 bar fuel pressure on one and and 1 bar air pressure (boost) on the other. 4bar - 1bar = still 3 bar.

This system maintains the same fuel pressure across the injector no matter what the boost is.