Help with fuel injection issue

Hook up a fuel pressure gauge.To see if the fuel rail is holding fuel pressure for a while after you shut it off. When the engine is at operating temp. Also check the vacuum line going to the fuel pressure regulator. To see if you have fuel in the vacuum line. I used to work on jeeps at the dealer ship, but that was back in the late 1990. Lol there was a message about jeeps and hard starting. It was something to do with a check valve in the fuel pump/ sending unit. But it sounds like you allready replaced it.