Fuel pressure bleeding off??

[squarebush]

I recently been having issues with the pressure bleeding off the fuel system after it sits for a minute. I have to turn the key on/off 3x to re-prime or it wont start. I put a fuel gauge on the injector rail and confirmed after 5 seconds it goes to zero.

Any way of checking if its the check valve in the fuel pump vs. the fuel regulator/spider etc.???