My son has a 2005 Focus with a 2.3L engine. When he goes to start it, it will crank but not start. He cranks it for a few seconds, stops, and then cranks it a few more seconds and after a couple of cycles of doing this it will start and runs fine after this. It started out as a intermediate problem but it is doing it more and more frequently. I am thinking fuel pump or coil packs. What is the minimum fuel pump pressure it needs to start if it is the fuel pump?