So I had some time today and decided that I was going to time the 75 F100 with a 360 and automatic 2 wd.


when I was all done I disconnected everything.

the truck ran fine for about 15 minutes just sitting in park idling and then all the sudden it sputtered and died. So I started it and it started right up and it ran for about a minute and died again it did that about three times and now it won't start at all.
I checked for spark and I don't have any.

I checked the coil wire and all the ignition wires just to make sure I didn't knock anything loose.
everything looks just like it should.

the distributor is new however the coil is not.
should I start at the coil or should I start at the ignition control module? Btw the icm has a black grommet. Truck was made 12/74. VIN plate says it's a 75.

 

Sounds like the Ignition module bit the dust.

 

F100, there are many threads discussing the ignition system for your truck. Assuming that you've verified that this isn't a fuel issue (by looking into the carb, moving the linkage and watching gas squirt from your carb to the intake), then all that's left is spark and compression. Yes, the ignition module can be getting warm and puking, but it's best to take a methodical approach in lieu of just throwing parts at the problem. You will be a better mechanic in the long run, Let us know what you find out (e.g voltages and wires at different points, etc.).

If you don't see fuel moving in the carb, then you may have a fuel delivery problem (e.g. blockage, pump issue, etc.).

...and sorry I advised you the way I did, despite reading and understanding your post the first time; I'm just retarded . Not really, I was just trying to give you a thorough approach as you didn't really articulate how you determined that you had no spark and it wouldn't be the first truck where the actual failure was not as initially reported. Since last checking in, I see you have a slew of others providing great next steps and things to cover. Peace.
Cheers,
- IH

 

Easy to check the ohms on the distributor stator and ignition coil.
Disconnect the distributor connector and put the probes on the colored wires (Orange and Purple I believe) and you should see between 400 and 700 ohms resistance. If it's outside of that range it needs to be replaced.

The stock coil has specific readings that can be taken as well, but I don't have those off the top of my head. Every service manual lists them however.

I forget how to check the modules themselves, but it's easy enough to verify power at the connectors.
Hopefully others will remember the details on checking the module and coil.

Paul

 

OP already stated he is not getting spark. Read the posts before responding....

 

Closely inspect the wiring at the Duraspark ignition box. The insulation has been known to go away. It can shrink back and out of the plastic connectors, exposing the copper conductor. I've also seen it go brittle, and flake off of the copper. Check all of those wires all the way to the distributor, all the way to the coil, and all the way back to the cab - or follow them where ever they go.

If you just now changed the distributor and still have the old one, try putting it back in.

 

X2
Besides they are not a lot of money so if it is not the ICM you now have a spare.
I have had 1 in a 76 AMC and a 83 Merc car go bad in the mid 80's.
Changed them out and never an issue of either car just stop running.
Dave ----

ps pull the dist. cap off and make sure the rotor is spinning when you crank the motor.

 

I bought the truck a couple of months ago and the distributor appears to be brand new. The cap was new the rotor is new... the metal part is real shiny and the wires are new and has brand new connectors. There's also a fairly new looking spark plugs and wires.

The part that is real weird is it supposed to be a 75 but the grommet is black which is supposed to be for a 74 so which one do I buy a 74 or 75, and where do I get one with a black grommet if that's the right part.. everything I see online is a blue grommet. The module says Motorcraft right on it and it has a significant amount of oxidation so that's definitely not a new part.

 

If you get a chance I'd personally like to see a close up shot of the module. Wire connectors and wire colors and all that. If it's original (would an original say "Motorcraft"?) that's be some good reference material for the future.

Normally you only use the same color module to replace one, but there are a few here that have listed a few compatible modules that can work when connected to the wiring of another.
The blue grommet was the last iteration I believe, and the one you find on most vehicles these days. Also the module-of-choice for retrofitting Dura Spark to an older vehicle. It's therefore usually easier to find too.

The fact that the distributor looks new, unfortunately does not necessarily bode well for your testing. These days "new" usually means "questionable quality" too and you may just have run into a coincidental failure.
Some things to verify then. You need to test the resistance of the stator (magnetic pickup coil) inside the distributor. Measure between the Orange and Purple wires and you should see between 400 and 700 ohms. If it's near the outer ends of that, or beyond, you need to replace it.
Make sure the ground wire is connected under the cap. This is the third wire in the connector, Black sometimes with a white stripe. It should be visible just inside the distributor and have a screw holding one ear of it's retainer to the body of the distributor. This wire then connects the module to the distributor for a coherent connection especially when the module is bolted to a plastic inner fender liner like on some later trucks.

If you have a radio noise suppressor capacitor on the positive side of your ignition coil, temporarily disconnect it. If it goes bad and is partially grounding out through it's case, it can stop the coil from building up enough juice to spark.

Measure the resistance of the coil based on the tests in the books. I don't remember the values, but others will. It's important to test these things.

Verify you have 12v on the module's Red wire when the key is ON.
Verify that there is still a good connection on the Green w/yellow module wire to the negative side of the coil. At the same time, make sure that the horseshoe connector on the coil is in good shape and the wires are clean, tight and not looking frayed or worn.

Got pics of your under-hood area?

Paul

 

You can always just start replacing stuff too, but that usually ends up being expensive and frustrating when you find it was a disconnected wire, or clogged fuel filter after spending a couple hundred dollars on new parts!
Just sayin...

I would not put it past a previous owner to have installed the wrong module, but I would also not put it past Ford to have made it a running change rather than an absolute year-model only change either. Being a 12/74 build, it's obviously a '75 model. But perhaps they still had some laying around and a few accidentally got in the bins. If the '74 and '75 modules were two of those that happened to share the similar connections, I can see that happening on the assembly line.
But more likely it was just a running change and some didn't quite get what was expected per the documentation.

Old coil (I just re-read your earlier post) could be at fault too of course. Maybe find out what the ohm readings are supposed to be and check it while it's hot.

Paul

 

Thanks Paul.
I'll get some pics.

 

If it has a black module you have to replace it with the same. The black module has a different wiring pattern than other modules. IGNORE the advice on testing there are easier ways to test for power. Using the blue wire at the module.check for 12V at Start and 6-8V at run. This will verify the WHOLE system for power.

The Black module is technically not a Dura Spark ignition system but is SSI (solid state ignition) No one makes a direct replacement for this module they are all modified Blue DS II modules wired to replace the 1974 SSI Black module
Fords SSI had active dwell control for the coil, and could be fitted with crank retard things DS II was not capable of. SSI was closer to GM's HEI in terms of operation they just were not high output.
The Green 1975 SSI modules are identical in operation to the Black modules but are wired differently and have a different ampacity rating.
The Black Module uses the standard points ignition coil that Ford had been using since 1950 or so. The Green module uses the standard DS II ignition coil. Yes the coils are not the same between the 2

So you need to replace the components with like with the Black module and not just throw DS II bits at it. if someone replaced the Coil with a later DS II style coil it would explain why the module cooked it's self. Is there a part number on the coil ?

 

5V at run. 8V at start. Using the blue wire.

 

Inside distributor

 

Coil numbers.
The numbers in the box to the right are 4KBA