View Full Version : Fuel regulator functionality/theory question

10-02-2006, 10:31 PM
Ok, another of my near endless "I don't have a turbo car so have to guess how this stuff works" questions....

On the NA SFI Buick V6, my assumption is that the fuel pressure regulator, due to manifold vacuum, is nearly completely open (ie: allowing a lot of fuel to return to the tank), at idle, and other situations of high-vacuum.

When there is no vacuum (WOT, or vac hose removed from regulator), I assume the plunger closes off completely, thus maximizing fuel pressure.

Is this assumption correct?

If so, then for a boosted car, is the difference just in the regulator's design? That is, a turbo vehicle's regulator does not close off completely at zero vacuum, but only does so at a predetermined "maximum" boost?

Or is there something else at play?


10-03-2006, 09:52 AM
Actually, the fuel regulators are the same on the N/A and the turbo cars. In fact, and early modification was taking the "237" regulator off a Somerset Regal and using it on the TRs, since it provided more base fuel pressure.

They are pretty simple devices and work on pressure differential across the diaphragm. As long as you don't exceed their flow capacity, (like a full tilt dual pump system can "flood" a regulator unless you stage the second pump), they work to maintain rail pressure.