fuel system on OBS...
Line from tank to low pressure side of pump
out of lp side of pump to input of filter
out of output side of filter to high pressure side of pump
out of hp side of pump to rear of heads
through fuel galley where some fuel is used
out of fuel gally (front of heads) to fpr
out of fpr through return line and back to tank.

Question: Where exactly in this series is the fuel filter restriction (vacuum) sensor?
This sensor turns the light on when the vacuum gets too great?
If a dirty filter creates more vacuum (turning on the light), and the fuel line goes directly from tank to low side of pump, then it must be after the filter and prior to the high pressure side of the pump.

Is this all correct?