I've got 1998 Explorer; 4.0 EFI V6...
It just started doing this again - had a bout of it a year and a half ago. The starter cranks the engine over just fine - it simply will not run - no lights dimming, so battery is fine. I can hear the fuel pump running before cranking and there is fuel pressure at the Schrader valve on the fuel rail. There is voltage to the coil, and the primary and secondary resistance in the coil is within spec. The engine doesn't sputter or try to run at all. The first time we had this problem, it was towed twice to the repair place (about 25 miles away and not cheap - we live in the country), and of course when it was unloaded from the truck, the stupid thing started right up, so they couldn't track the problem. Since we got it home after the second tow, it's run alright until today. One of the techs suggested it might be the electronic thing that keeps the engine from starting if you use a key without the right "chip" in it. Does this work by preventing spark? If so, is there a way to bypass this to see if it will then start? I thought of something like an ignition control module, but my shop manual for this truck said there isn't one in Explorers after 1995...must be integrated into something else. So why would it act like this a year ago, but then be fine until today? It is giving no codes to help with diagnostics.
I read in one article online that it's possible the ECM Relay is bad...where is that? There is no relay labeled as such in the owner's manual or the shop manual.
Thanks for any advice on this. It's basically a 4000lb paperweight at this point.

 

If the fuel pump comes on then the ECM relay is fine. Would suspect the crank sensor is bad if I had to guess.

 

I had your exact same problem on my 94 Ranger 4.0 back when it was less than a year old. Towed to dealer and it started just fine. It was the EEC relay. 155,000 miles later and it's never done it again. The relay is located in the power distribution box under the hood and on top of the left wheelwell in the Ranger; I'd expect a similar configuration in the Explorer.

Some people have reported that if they snap the relay with their middle finger (lock your middle finger under your thumb, release and snap) the relay will work properly.........for awhile.

 

I think i agree with opera house.....sounds like your crank shaft sensor to me also....thats the only thing ive ever had go bad where everything shows to be fine but it just wont start...sounds silly but i replaced $150 worth of electronics over a $9 sensor...i would check into it

 

Thanks a lot guys. I have some free time tomorrow, and I'll get in there and see what I can get done.
Thanks again for some directions to try!
Mike