So, as I backed out of the driveway a few weeks ago, the XJ8 stalled. Thats never happened before so I knew I had a problem. My son came over and we checked for pressure on the fuel rail. Absolutely nothing!. My son figured the fuel pump died and after trying a few other things, we decided to replace it. So, the first thing we did when we got the tank out far enough was to drain all the gas out. What a shock that was. We siphoned the gas into a clear five gallon jug. More than half was water! as my son was taking the old pump out, I removed the fuel filter. We drained the line, got all the gas out of the tank, installed the new pump etc, and put it all back together. It didn't take all that much to start the engine and I was up and running. I had had a no start problem for weeks and it seemed it was all due to the water in the tank.. I've had no problems since then...
Wow..

 

Have you checked the drain line next to the filler cap? They do get plugged with debris and the filter has to be lifted out to clear.