Hard to start. Cranks well and runs fine when it finally starts. I've replaced the fuel filter, then the pump, then the pressure sensor. When I measure the pressure at the rail it is near zero. When turning key to ON the pressure blips slightly. Sometimes it builds if I cycle the key off and on a few times. When cranking the pressure comes up slowly and finally after starting it is steady at 50psi. When turning off the key it immediately falls to near zero. This is the non return to tank system with a single pump. There's a rubber hose with a round can on it going from the rail to somewhere out of sight on the drivers side. I get the feeling that something is allowing the rail pressure to quickly bleed. No service lights or codes thrown. Can't get my head around it. Any advice?

 

check the fuel pressure regulator on the passenger side, just in front of the rail. Mine was cracked and leaking, but it is a small diaphragm inside that releases pressure on the fuel rail when needed. It has a line going to it and away from it.

 

There are some 2003 and later replacement pumps with bad check valves. See https://www.jaguarforums.com/forum/x...l-pumps-78107/