I finally got around to using some of the great advice supplied by "greydog" about fuel pressure dropping after the key is cut off (or after the pump is no longer running). He had to replace the check valve on his fuel pump with a new one, but I repaired mine on an '81zxt at no cost! Takes a deep well 14 mm socket to remove the outlet barb from the fuel pump. This little part contains the spring/check valve that maintains the pressure after the pump is cut off. Mine was full of a rusty colored crud which prevented the valve from working. About 10 minutes of gentle scrapping and prodding with a straightened paper clip had it working again. 30 minutes total and it was back on the car and now holds 37 psi with the key off - to early to tell about 24 hours later. Determining the problem was also easy with the fuel pressure gauge properly located after the fuel filter & before the fuel rail. Turned key on, pumped up pressure to 40 psi, and crimped the rubber fuel line before the gauge a second before the 5 second pump primer cycle ended. Pressure held at 40, so problem was, in fact, the check valve at the pump.