it's a 4.0 v6 auto tranny. has done this before a few times then would fire up but this time won't fire at all. turns over fine - but no fire, was running fine yesterday eve but no runny today
I've got the idea this is something really simple anyone have ideas of what I should check?

 

Can you hear the fuel pump running when you first turn the key on?

 

Do you have a CEL lit???? If so, scan the computer for trouble codes & post All code Numbers, as they can provide good trouble shooting clues, like for a failed Crank sensor, whos output signal the computer uses to ground switch & fire the coilpack to make a timed spark.

If no trouble codes are set, it suggests that something is wrong that the computer isn't monitoring, so since you say you have no spark, check for B+ at the coilpack electrical connector at KOEO. If no B+ at the coilpack electrical connector, check fuse, or B+ feed wiring for damage or corrosion, or for a B+ feed problem from the ignition switch. If you can hear the fuel pump run, the ignition switch is likely ok.

If you have B+ to the coilpack, check the coilpack primary & secondary windings for continuity. Primary winding isn't speced by Ford, but typically measures 1 ohm or less, like .5-.7 ohms. Secondary typ is 13K-15K ohms.

If thats ok, remove the coilpack & look for cracks underneath that could cause HV leakage to ground & a weak spark. The coilpack is known to crack underneath.
If thats ok, & you still suspect the coilpack, most autoparts stores can bench check the coilpack for output at no cost.

If the coilpack checks out ok, maybe look to problems with the coilpack ground switching wiring, from the coilpack electrical connector pins/sockets back to the computer firewall electrical connector pins/sockets. If its ok maybe suspect something with the computers ground switching drivers, so make sure the computer to body & body to battery & battery to engine ground connections are clean, bright & tight & if ok, maybe suspect something is wrong internally with the computer coilpack ground switching drivers, although its not likely that all wiring or drivers would go bad at once.

More thoughts for consideration, let us know how your trouble shoot goes.

 

Could be as simple as the EEC relay. If it is acting out you will get the same symtems at times a no start because the computer is not powering up. when you turn the key on with engine off does the check engine light light up? if not, it could be the EEC relay! If thats the case try switching it with the A/C Relay ( They are the same )

Just an easy thing to check

 

the check engine light was'nt lit, no spark and no fuel pressure at the scrader valve.
I did clean with circle wire brush on die grinder the ground leads attached to the radiator wall folowing a suggestion from one of the forums. behold it fired right up!
I'm going to perform some of the checks that were mentioned in addition.
thanks to all for replys!
I'll post any further results. since it lights off instantly when it does fire it's bound to be something very basic
sort of wish I had turned the switch on but not cranked engine and checked for fuel and CEL first before turning over.