On the supercharged, I don't know. On the non-super it's at the other end of the fuel rail. There is a vac hose attached. Vac opens the regulator and allows fuel return to the tank. No vac = closed. Pull the hose off, if there is a strong fuel smell in the reg or hose, the reg is bad. With your fuel psi gauge attached there should be an increase in psi with hose off - from 34 to ~50 or so. 34 would be a bit low for a non-super engine. 44 would be better. You will need to look up the specs for your engine - Chiltons, etc. You could check it off the vehicle by pressuring up and seeing when it opens. I have never heard of these people before but the article is worth reading: