The cat is back!
 

As it turns out, my theory about the tank being empty was correct. All of the fuel must've been returning to the right side tank, and the left hand tank was empty. So there was obviously no fuel pressure. I disconnected the fuel filter without depressurizing the system (oops), but what came out was a bunch of compressed AIR! That was the first indisputable sign that the fuel had run dry.

It took me a long time, but I finally got a brass fitting from Home Depot with 3 barb adapters that hooked up to the fuel lines in the rear. FYI I think they are 5/8" I.D., not 7/16". Big difference! I ended up getting a flush style tee fitting with flush connecting barb adapters. You really have to twist those really hard before you get a watertight (or gas tight) seal, but once it's sealed that sucker ain't going to leak!

I'm so happy and it has reinvigorated my interest in doing a partial restoration of this car!

I think I got a steal at $800 + $30 fuel filter, $90 fuel pump and $25 in brass fittings.

Well anyhow, I finally got to take my highly anticipated "first drive" in the Jag. I drove it around the parking lot a few times, and then I finally worked up the courage to go on public roads!!! I see the transmission has the same "thunk" when coming to a stop as my 2006 XJ VDP had--it must be part of that Jaguar charm! The HVAC doesn't work and neither do the windows, so I had to turn back before I couldn't see anymore. The front suspension is clanking and feels pretty loose--I wonder if it's because of the upper shock bushings or if it is something more sinister.

The engine idles perfectly smoothly and now it revs freely--I think letting it run and have that Techron move through the fuel system will only make things better!

By the way I wanted to thank everyone who gave me all the good advice and things to check. I'm sure I will need some more tips in the future! Thanks all!