Flash319

So I think my vac hoses are messed up. The diagram that I got from the FSM for 93 shows full vacuum (from behind he throttle plate) and the hose going to the fuel pressure regulator on one side of the VSV and the other side (single port) going to the front of the throttle plate?? This would put full vacuum on the regulator. Is that how they work? Full vac lowers pressure or increases it?

Then I saw a diagram on pirate showing one guys truck with the single port from the VSV going to the pressure regulator and the other side going to full vac? How should the regulator be hooked up?

scope103

I'm not sure I follow your description of the vacuum routing, but to answer your question: yes, when warm full vacuum is put on the fuel pressure regulator. The idea is that fuel quantity is controlled by the time the injectors are open, so that requires they have a constant pressure across them. When vacuum increases, the fuel pressure decreases to keep the pressure across the injector constant (the VSV increases the fuel pressure slightly when cold).