????
I suspect regulator leaks inside tank.

 

It should hold for a while but will eventually relieve some of the pressure into the tank. you can use a gauge to verify, google your problem will help also. If you are having slow starts because of this issue you think you may have, try priming the pump (turn 2 clicks for about 5 secs) or twice then start it.

 

More than a day...at least.

 

IMO, I think a day would be streaching it. I did a check of my system not too long ago and I found the fuel pressur stayed above 30psi for about hour, but continued to drop as time went on.

How quickly is yours dropping? Does the fuel pressure come back up to 45+psi when you turn the key on (before start)? Does it maintain 45-50 while running?

 

Thanks. I need to check some more.
Symptoms are like on previous Cherokee, starts after about 5 sec turning.
It also has loss of power while driving, but I have bad cat converter and dent in exhaust pipe, I am dealing with exhaust first.