Fuel issues

I'm having some fuel problems on my 92. The fuel pump comes on when the key is on but it stays on and won't pressure the system. When I'm under the hood, I can hear what seems to be pressure escaping somewhere near the rear by the firewall. Suspected FPR and changed it but to no avail. Problem still there. Someone mentioned a fuel flow regulator but I can't find any info on such a thing. None the less, the fuel pump comes on and there is zero fuel pressure. Any help is appreciated. Thanks.......

Thanks, I was planning on dropping the tank next weekend. This tank does have some rust in the bottom I noticed when I put the Walbro in but I didn't have another tank and the car is my driver. I'm wondering if the FP strainer might be clogged. I have another tank to put in it now and a new strainer that I got about 2 years ago. Maybe that'll do it, I don't know.