My 1979 f150 with the 351m and c6 will be driving and suddenly shut off. Sometimes it'll just start up without me touching anything, other times I have to crank and crank then it starts. It does NOT stumble when it dies, It just stops firing, which is telling me it's electrical.

There is NO reoccurring pattern, it is random.

I have great grounds, already swapped out ignition module, brand new distributor a few months ago and all fuses good, also have a new coil and resistor as well.

I have read several forums about this but all were slightly different than my problem. Anyone have any idea before I start testing wires out in 2 degree weather?
Thanks guys

 

Maybe the ignition switch? How much crap ya got hanging off your key?

 

Try your ignition switch, mine died in the freeway and then fired and finally died .

 

I will order an ignition switch. It looks like it's the original switch. Any other suggestions?

 

On my old 78 I found 1 of the 2 wires to the coil was corroded about 1 or 2 inches back from horseshoe connector.Cut it out and soldered a new wire.On another car It would run fine and die it was the fuel pump going out.

 

Well it wasn't an ignition switch, getting a new coil tomorrow

 

Isn't the coil or resistor either. I girl I start checking wires

 

I seen that you replaced the module, ive actually bought one way back when from autozone and it was brand new and as useless as the old one,id really look into that module again

 

They don't like it here but if you are pulling hair a good HEI will get you rolling again.. (I like mine)

 

Replace the pickup coil in the distributor. Even though the distributor is "brand new" a few months ago.

 

Agree with "just 'cause it's new, it should work" but doesn't theory. Re-check the brain box - get a Motorcraft if you haven't already, recheck your pickup coil in the distributor as previously mentioned, and check the wires inside the distributor plate for connection/brittleness.

It really sounds like an intermittent ground, insulation rubbed off a hot wire and is shorting the system out, and/or a semi lose (+) connection. Solenoid ok and bolted to a good, clean ground?

Connections to the coil good and snug....not frayed or lose? Orange and purple wires resistance from distributor ohm out good? - between 400-700 ohms?

 

Found the problem!
First, thank you for all the responses and I hope this will help people in the future.

I checked my pickup and I started tracing wires, then it just came to me. My coil was leaking, thus over heating. I'm guessing that backfed power to the icm which fried it. So I got a new coil and a new icm and it's been fine.

 

Glad to hear you're up and runnin'

 

My truck is doing the exact same thing..
I will check my wires and brain box

 

When you replace the coil, make sure the semi circular looking connector that slides over the primary terminals is tight. I have seen the contacts lose their springiness and cause it to cut out like you describe or not start. That connector is a common and inexpensive repair part, so if it is loose at all, go ahead and splice in a new one. Hope this helps.