I have a 2004 F-150 with the 4.6L.  It has 232K miles and I've had it for just over a year now.  It has a 'personality' when it comes to starting and I'm afraid to drive it for fear of it not starting.

It seems to happen after it gets wet, either from a undercarriage wash or going over puddles.  When I did the undercarriage wash, the truck ran on on my way back to work.  It started when I went home from work that night, but wouldn't start the next morning.  It would crank, but it wouln't fire.  It started fine the next day.

It has also not cranked at all - turned the key, lights come on, but no starter.  I'll head out the next day and it fires right up.  The battery and alternator are new, have been checked, and are in good condition.

Any help you can give on where to look for a problem would be much appreciated.  I'd love to drive it places without the fear of not having a ride home.

My 2007 did this and it was a fuel pump driver module.

It was located on the frame by the spare tire.

It is alum. and plastic and it corrodes and water gets in.  

Maybe????

Probably.  Easy fix though.

That looks to line up with some of the symptoms and it's a common problem.  I'll check it out.

Thanks!

Check the ground connections for electric pumps.
The crappy frame connection is often barely there.

Lookie what I have in the shop today! ;)

Got mine off today.  There wasn't a big hole, but it did go through the casing.  I cracked it open and it was full of sand and dirt.  You also see a moisture signs in there.  Got a new one coming

Thanks!

Use the spacers if they come with then new one.  If it doesn't come with them, make some and use longer bolts to get it up off of the frame so it won't hold dirt/salt/crap between it and the frame crossmember.

I put the new one on and it started up faster.  I started it up this morning and backed it out to the middle of driveway to clean it out.  I went to head to the store about an hour later and it wouldn't start (but it cranked).  I tried several two more times about 10 minutes apart.  I dug out my spark tester, removed the COP, tested for spark, and it started.

It's about been 10-15 degrees out today.  It only had this behavior when it's cold out but it's very intermittent.  I'm at a loss on what could be wrong.  The only thing I can think of is a bad crank sensor or computer.

As far as the no crank, check firewall solenoid.

As to the rest of it, does the truck do anything else odd electrical wise?

Nothing 'odd' beyond cranking too long and too much.  It never shuts off while driving, just acts up during startup.

I'm starting to lean towards the anti-theft PATs system.

Your plugs aren't completely worn out are they?

Does she smell really rich when it does start after a long crank to start? If so, your fuel injectors could be bleeding off after a long sit like over night. Maybe only one is stuck open? Easy to change. Maybe two hours. I bought some rebuilt injectors for my 01 5.4 for $250 exchange. fixed a bunch of problems, one being long crank in the mornings. These years had the PCM plug sticking out over the passenger side fender well too, take a look on the firewall for corrosion or other obvious signs.

WSS

ETA: just re-read your posts, happens when cold" Our 01 had this happen. We live in so cal and the vehicle rarely see anything below 45f, well we took a trip to snow and the pcm went out. Not all at once but things like idle control, long cranks, sensor codes etc started showing up. Replaced the PCM and all is well again, just did this last week. Had to call a locksmith to reset the PATS after the PCM install.

can you verify that it's not just the fuel pump?

Possible - I got the truck with over 230K on it and I don't think it was 'well-maintained.'  It either starts or it doesn't though.  No running rough at times or 'bucking' as if it was mis-firing due to a bad plug.

I am getting long cranks, but no sensor codes.  What did the PCM and PATS costs?

I hear it hum when I turn the key to 'on.'  It's so intermittent that when I go get a loan-a-tool fuel pressure gauge from the auto store, it starts up when I get back.  It doesn't seem like it's starved for fuel when driving and under heavy load.

Could be injectors bleeding down. The PCM was $199 and pats re-do was was $180, should have been $100, the guy that did it had done "100s" of them and never saw my problem LOL. I called the place I bought PCM and they said he should have done the master reset first then it would all be done. I had to pay another "token" twhich was $80. If he had done it right the first time, it would have been one token and a $20 call out charge. It does run good though. You may be in need of lots of maintenance stuff, injectors, plugs, COPS, o2 sensors, maf clean or rebuilt, etc. You might say a "major tune-up". Have you ever cleaned behind the throttle plate? It's a common gremlin when really dirty. There is also a vacuum elbow behind the throttle body, between the intake and throttle body that rots or dries out too, you can only see it whith a mirror.

WSS

I had a very similar problem with an 02 I changed the fuel pressure regulator and have not had the problem again.