I have a 1990 Ford F150. Cranks but wont fire.

If everything is checking out ok the plugs must be fouled out and not firing.

I don't suspect that is the problem as it ran perfectly once second and not the next. Also there is no spark from the high voltage coil wire. I'm curious how the coil is grounded?

Instand of guessing remove one of the spark plugs out plug back in spark plug wire and hold plug close to a ground and have someone turn engine over you should get a spark if its firing. If you get a spark the plugs are not firing and if not check ground to coil.

I tested the main output coil wire and got not spark. I also did the test you are suggesting and again got no spark.

If know power going to coil check ignition fuse.

I have tried 2 new coils to no avail and I guess it is possible they were both bad. Is there any way to test a coil independent of the vehicle? IE some kind of resistance test?

Take your distributor off and have someone turn it over. While you hold the distributor out of the way. See if it's not turning big problem if it's not. Because the gear in your engine is plastic and need's replaced. Good Luck

Same here with my 90" f150 4.9litter , sum kid backed into the passenger side front, (had to replace radiator) , and it ran like a champ. On the 3rd day later, on my way home the truck sounded rough, than it caught on fire. Pulled over & put it out. Had it towed to my place and its been sitting for 2weeks now. I've changed the valve cover gasket, coolpack, spark plugs, wires, radiator, map sensor, & now just today , the "ignition control module" that goes on the side of the distributor. I turn the key, fuel pump comes on, battery is lil pass the half mark, motor is turning over "starter is great", but No Fire. I checked everything 3times personally, I've had 2 long long time professional/ licensed mechanics, and they all tell me the same thing after going over it for hours .. "Everything is intact, other than lil bit of water in the oil, everything looks good to go !! , but idk what to tell ya son" .. So hopefully you're having much better luck than I am & perhaps, could let me kno what caused your motor not to fire. Bc at this point I'm on th ed edge, spending 2k just to buy the truck & replacing $347 worth of new parts & still isn't running .. ya, I'm regretting not buying a Toyota Tacoma when I had the chance ...smh

The only suggestion I can give you is to clean the plug that attaches the coil to ICM. Clean it super well. That seemed to solve my problem.