My 2001 f150 xl 4.2l With 125k miles will also crank but not start. No codes but thanks to forum members advice, I hooked up a scanner and it showed no rpm while cranking. The fuel pressure is 35 psi. I pulled a plug and grounded it, but no spark. Prior to it not starting at all, it would start using starting fluid but even that took more and more fluid over time. Eventually, it started to stall at red lights, then one day it wouldnt start at all. Before it totally crapped out, i replaced the CHT but apparently that wasnt the problem.

I located the Crank Position Sensor (CPS) on the lower front right side of the engine (as viewed by driver) just above and behind the harmonic balancer, which is the heavy pulley at the lower front of the engine that drives the serpentine belt. The CPS is fully external to the engine and is held on by 2 8mm bolts. I replaced it for $20 and now it starts and runs just fine.