no vacuum at throttle body to control pressure regulator

At the port on the throttle body that leads to the pressure regulator,
there is no vacuum at idle, as indicated on my pressure guage (I think it
should be about 18in.). When the butterfly valve is opened, the vacuum
acts accordingly. Any ideas?

 

When I've put my finger over the hose leading to the pressure regulator at
idle, I've noticed VERY little vacuum. Since it is this way on both of my
Saturns, I've assumed it was the way it normally operates. When the
throttle is opened, vacuum increases substantially and causes the regulator
to 'obstruct' the fuel return path (in a return system) to increase the fuel
pressure in the rail.

Lane [ lane (at) evilplastic.com ]