Fuel Pressure Drop Question

[6SENSE]

Had my engine apart for awhile, just got it back together yesterday. Noticed that unless the car is running my fuel pressure drops down to 0. If I put the key in the ON position the fuel pump primes the line and the pressure goes up like normal, but as soon as the pump stops the pressure drops.
I think I remember something like this happening in the past. Maybe years back when I put the car together for the first time, but I dont remember exactly what caused the problem then. Any ideas?

 

[Turtle TR]

LOL, I thought that was normal for pressure to drop ...so maybe it isnt?

 

[mybuick]

it would be one of three things
1 leaky injector
2 bad fuel pressure regulator
3 on the fuel sending unit there is a pressure relief valve it is made of rubber and that could be bad

 

[6SENSE]

I couldnt find any problems, but wouldnt you know it magically started holding pressure on its own today. Might have been some dirt in the lines or something that was causing the regulator or an injector to hold open . Oh well, not complaining, cars running smooth. Good to be driving it again