I need some suggestions since I am away from most of my tools, although I do have my DMM

 

Some of those earlier models had a starter solenoid with 2 small terminals one should say I ignition and the other be stamped with an S, that way the coil will get power while cranking and power will stay when the key is released. Use your DVOM and check for power to the coil with just the key on. they used resistors of some sort to cut the voltage down at the coil after cranking, and during cranking you should get a full 12.6 or somewhere about. Once the engine starts the resistor cuts down the voltage to 10-12 so you dont burn out the coil. you need to trace the wire that powers up the coil with the key on.

 

With the key "on" check for voltage at the coil + terminal. If you show voltage, next, disconnect the battery cable that goes from the solenoid to the starter. This is just so the starter doesn't turn over. Now, turn the ignition to the "start" position and check for voltage at the + coil terminal. If you show voltage there, I would suspect four possibilities. First, the solenoid, which you've already replaced. Second, a wiring problem. Like David7.3 said, Ford uses a resistor wire and these do sometimes go bad. It's rare but it does happen. These can be "wired around" by using a regular ceramic resistor wired parallel to the original circuit. Next, a bad ignition switch and last a bad ignition module.
The thing about intermittent problems is, unless it's acting up at the moment, they're difficult to troubleshoot and once you fix it, you're not really sure it's fixed.

 

with battery at 12.3v, coil at "run" has 6.47v, at "start" has 11.9v

next step, please?

 

If you have a test light, touch it to the negative terminal of the coil and crank the engine. It should blink as the engine turns over.
While you're there, check the resistance between the - and + coil terminals, it should be less than 1 ohm.

 

The fact that the coil voltage drops in RUN means that both the coil and module are getting powered properly - the drop in RUN tells you that the module is grounding the coil at a stand-still, as it should.

In addition to what Mike has described (which will help isolate the problem to either the primary or secondary sides), check the resistance between the ORANGE and PURPLE wires coming from the distributor. It should be between 400 and 700 ohms. Neither wire should have continuity against the BLACK wire (total of three measurements). Often times, if the pickup fails (which is what you're checking), it will not switch the module while the engine is cranking, but letting off the key collapses the coil, which gives that final spark.

If the BLINK test BLINKs, then my test is a moot point. I'm just listing it out now in case I'm away when you report in.

 

Thank you both for your patience, I am living in a motel and, working 2nd shift, I dont necessarily want to hang out there at night in the parking lot.

The results of the testing

1. Light BLINKED as starter turned engine over

2. 1.5ohm across coil terminals

3. 647ohm across ORANGE and PURPLE wires from dist

4. DMM read "OPEN" ORANGE to BLACK and PURPLE to BLACK


On #2, at first I could not get a reading that was stable for 10 or 15 seconds until it finally settled to 2.8ohm. I cleaned the terminals with scotchbride and that dropped the time to immediate and measurement to the reported number. Dist was replaced 2 yrs ago because vac adv mech was corroded and locked up, along with plugs and wires, when I got the truck running. Coil and ign module remain as purchased from PO

 

So, is #2 too high? What do I check next?

 

All of your observations (1 through 4) are perfect. They tell you that the entire primary side of the ignition system is in perfect working order. If there is no spark in the presence of these conditions, then the problem is isolated to the secondary side - distributor cap, rotor, wires, or plugs. Note, however, that these items have no "sense" of the position of the key, so a problem there would not correlate to your original observations (only get spark when you let off the key). In other words, your two sets of observations can't co-exist, so something changed, or is missing from the story.

 

Ok, so... Monday rolls around and I head out of the room to head to work and the truck absolutely refuses to start. After 45 minutes of trying, I call in and announce I will be late, put my charger on the battery, and jumped onto the forum to see who was on. I left a couple of PMs for Mikeo0o0o0, including a note that I had redid the testlight test again and that the results were different this time, i.e., no light until a faint flash as the key went from START to RUN. Eventually I got it started and made it to work only 2 1/2 hours late. Got home from work and put the charger back on while blocking part of the parking lot since everybody chooses to park in front of my door and I only have a 25ft extension cord. I checked the forum and got Mike's message and was standing in my doorway watching. One of my neighbors, a few rooms down and working in the next hanger, has a black 79 SWB 4x4 that is not currently drivable. He walks down and we start checking things out and comparing thoughts and showing him all of my test results and Mike's message. He volunteers to let me try his ign module in the morning, we try it and it works! Now, my big issue is that the problem is intermittent, so I suggest we put my mod in his truck to see what happens, just like swapping black boxes on an airplane, and see if the problem follows the module. SUCCESS! the @#$% gremlin snuck off to his truck and all he can say is

"Hey, my trucks never done that before!?!"

 

Also, is there a way to test out a module with a DMM?

 

Sounds like you may have finally got the problem tracked down .
As far as testing the module with a DMM. I know there are some tests that can be done to the module while it's on the truck. This is along the line of troubleshooting, but as far as testing a module to see if it's good or bad while it's on the bench, I don't know.

 

I recently had a similar problem with both 6 cylinder and 460 engines in 1977 F150. Both engines had same issues and the only things in common were the coil, ignition module, voltage regulator and alternator. The engine would start and then would go up and down and stall. I could turn around and restart it quickly with no issues. It would still run rough and stall again. Sometimes it would run several minutes and sometimes it would stall within a few seconds. Since I had taken out the 6 cylinder the year before and finally got to the 460 that I had never started before I naturally thought something was wrong with the used 460 or maybe a vacuum leak since I put on another intake manifold. Thought about it for a day and remembered the 6 cylinder would do the same thing. Called my trusty O'Reilly's just a few blocks away and asked if they could test it. They were able to test it and it showed low rpm bad and high rpm good. So the long and short of it was it can be benched tested. I wrote all this info just so people could understand the issues I had and how easy and FREE it was to check it out. Took me five minutes to get it off if that and 2 minutes to get to O'Reilly's. Good luck guys!

 

I took my module to two different O'Reillys and they did not have the adapters to test mine, but then, they did not have the adapters to test the ign module in my wife's 90 Ranger either

 

I'm glad I don't have your O'reilly's. Been pretty lucky with mine so far.