In addition to the good advice you have recieved-
Remove the fuel return line from back of fuel regulator. Install a piece of hose about 6' long onto the regulator and drape this hose over fender and into a container setting on floor. Jump fuse 4 to 6 and activate fuel pumps. Wait for flow to go into container. Should be a full hose of fuel not a trickle. If a trickle it is either the fuel filter or regulator. Moving this same test farther back on the fuel rail (where it connects to hose) would tell if it was the filter or regulator.
Randy- you've been help to me many times on this board. Now maybe I can repay the favor. I made a cheap fuel pressure set-up by going to junk yard and cutting the metal tubing loop at the back of the fuel rail and a short piece of the hose that was connected to it along with the banjo fitting. Remove the banjo fitting and piece of hose (more on this later). Get a nice square cut on metal tubing. I did not try to straighten loop but just let it remain looped. This part is the key- take the metal loop to the hardware store and go to the plumbing dept. and get a 5/16" ferrel type of brass connector. Idealy this would be 5/16" tubing (ferrel) x 1/4" male pipe thread. Get a 1/4" brass or galvanized tee (pipe thread) and a 1/4" barbed connector. You can pick up your gage there also, I used a gage that is used on water systems and sometimes on air compressors, but you can get as exotic on gages as you want as long as it has a 1/4" pipe thread connection. Take the banjo fitting and slit the piece of hose and remove. Get a new piece of fuel hose about 6"-8" long and install it on the banjo fitting and the new barbed connector that you bought. Secure with small hose clamps.
To summarize- Metal loop connected to ferrell type adapter, tee screwed onto ferrell adapter, new pipe thread x barbed adapter into other end of tee, piece of hose, old banjo adapter connected to hose. Gage goes in the other opening on tee.
When you install on car to be tested. You break loose hose connetion at fuel rail, connect end of metal loop on test gage to hose in car, and connect hose from test gage back to fuel rail.
This set-up needs to be able to withstand pressures of 75+ PSI, so be sure hose can handle this pressure. Also be sure and use hose clamps.
A picture would be worth a thousand words but so far have not got to that point.
Total cost- about $12.