Educate me on the vacuum refrenced fuel pressure regulator used on the trucks. I'm used to dealing with F-body fuel systems with the in tank regulator. I'm interested in how the fuel rail pressure changes under high vacuum vs low vacuum and what happens when boost pressure is applied to the vacuum source on the regulator when running a blower.

 

The vacuum reference will lower FP when there is high vacuum in the manifold, this lowers the injectors fuel flow rate as there is less air in the manifold, there should also be less fuel. When the throttle is closed the vacuum is highest(lowest pressure) the FPR limits the amount of fuel pressure the injectors actually see. As the throttle opens the vacuum drops(pressure increases) the FPR allows teh rail pressure to raise up to and not over whatever the FPR is rated for. In my truck the FPR is rated for 60 spi or 4 bar of pressure, when my throttle is closed engine running, the railpressure reads 50 psi, when I crack teh throttle open, or if I have the pump running withthe engine off it reads 60 psi or 4 bar, this is because there is no vacuum being read by the vacuum referenced FPR.

To add boost you will need a rising rate vacuum referenced fuelp pressure regulator. This unit will add 1 pound of FP for every lb of manifold boost.

Aeromotive makes some awesome adjustable referenced fuel pressure regulators, some which can fuel 1600 NA hp on gasoline. Yiou can sett the base pressure then some models willl add 1 psi of FP for each psi of boost the intake is being fed by the turbo or blower.

I am pretty sure a stock FP wont register boost or over 14.7 psi 1 BAR, only vacuum or 0-14.7psi or 0-1 BAR of pressure.

peace
Hog