My 07 5.9 is not wanting to start. I've replaced the fuel return line in case there was a hole in the line. It has EFI Live custom tuning if that makes a difference and an Air dog 150. It's not throwing a code and I've narrowed it down to fuel relief valve, rail pressure sensor, or the FCA on the CP3. I don't really want to replace all 3 things just to find out what it is or if any of them are even the problem. It does start sometimes but still cranks longer than it should. Help a lady out.