Are you saying you have a stainless steel 3800 fuel rail? If so, that is a returnless fuel rail and it does not have a fuel pressure regulator in it. You will need one in the system somewhere.
Here's a picture of what I did:
Basically, I cut the fuel pressure regulator off a stock L67 (3800 Series 2 SC) fuel rail and used an AN flaring tool (37 deg flares) to flare the 3/8 line coming out of the regulator (after sliding the -6 AN tube nut and tube sleeve on) and connected that to a -6 AN steel TEE fitting. I flared the fuel supply line coming out of the stock Fiero fuel filter and put a nut and tube sleeve on it as well to connect to the bottom feed of the TEE. I then put a 45 deg -6 AN swivel hose end on the AN braided hose I was using down at the TEE. The return line coming out of the fuel pressure regulator is 5/16" and can be connected to the 5/16" return line going back to the Fiero gas tank via clamped on fuel injection spec rubber hose you can get at any auto parts store.
At the fuel rail, you'll need a -6AN male to 3/8" push-connect EFI fitting so you have something to connect the other braided -6 AN hose end to.
You can get all of these parts at Summit Racing Equipment. Below is the list and qty of each item you'll need:
2x -6 AN tube nut (steel)
2x -6 AN tube sleeve (steel)
1x -6 AN male TEE (steel)
1x -6 AN 45deg swivel hose end (aluminum)
1x -6 AN straight hose end (aluminum)
1x -6 AN male to 3/8" EFI push/quick connect (aluminum)
About 3 foot or so of -6 AN braided hose (if you mount your fuel pressure regulator near the stock Fiero V6 fuel filter location)
1x L67 (3800 Series 2 SC) fuel rail and regulator
SPECIAL TOOLS NEEDED:
37 deg AN flaring tool
Pneumatic cut-off wheel (to cut the braided AN hose to length with - apply electrical tape to braided line before cutting; then make sure you clean out the hose well after cutting to prevent debris for entering the fuel system)
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[This message has been edited by Darth Fiero (edited 03-19-2014).]