Ok I am a little lost here. My 2001 5.4L is just cranking and cranking. If I spray starter fluid into the throttlebody the truck will start and runs fine without any codes. Originally I thinking fuel pump but the fast that is started with fluid makes me thing the pump is fine since it continues to run. I was wondering if it could be a fuel pressure regulator issue. I'm lost at this point, can someone please point me in the right direction.

 

How many miles on the plugs?

 

What is the fuel pressure at the rail after the pump primes?