Ford Repair: 2000 Expedition Cranks But Wont Start, crank sensor, chevy dealer

Question
Hi, I'm a GM dealer tech with 20 years under my belt. I had to take an early retirement from a Chevy Dealer at 43 due to a back injury. I specialized in drivability, electrical, and fuel injection. I actually used to be a part of this web site answering Chevy technical questions a couple years ago.

Ok, My Son's 2000 Expedition with a 5.4 has an extremely intermittent "cranks but won't start" condition. Last winter it acted up a few times. All Summer it never happened. Last night it got down in the 50's and it just cranked away the next morning. Opening the throttle plate slightly and fully makes no difference, just cranks. So there may be an outside ambient temperature affecting the condition. When my son got home from school the Expedition fired right up without an extended cranking. It was 70 degrees then.

Every time I look at it, I can never get the cranks but won't start condition to act up. There are no DTC's (codes). All data looks within normal parameters. Has good fuel pressure. Has good fuel prime and pressure holds after pump stops. I kept my fuel gauge on there for a weekend and never seen a problem after checking it several times. My Son states theft light is not flashing. I'm leaning towards a no spark or no injector pulse guess. It's so intermittent, I think I'm just going to have to do some parts swapping, crank sensor, cam sensor, etc.

Any suggestions? Are there and parts that usually fail more than others?

Thanks,
Bob

Answer
Hello Bob, check to see if there is any possible water intrusion into the power dist. box and check the GEM module. The windshileds can leak and they will leak into the power dist box and GEM. That is a place to start and go from there. The evidence will be on the back side of the box. Hope this helps Thanks Tony