2hrs of perfection then dies :'(
 

1979 f150 460 auto 4x4

So I bought a truck today :thumbup:
Drove it from Alabama all the way to Nashville no problems. Was on the main rode maybe 5 minutes from my house and suddenly dies at 55mph. Toss in neutral and start cranking, slow crank eventually starts by the time I slow to around 15mph. Runs for a little longer I slowly start to give it more and more gas get to about 60mph and dies again. Turnsover faster this time. Make it back no issues after that.

About 30 minutes after I get back I start the engine again to drive it around the block make it maybe 200ft and dies, starts back up again but only after I turn off all lights. (coincidence?) Then no problems.

PO told me (and from cleanness I believe him) that he replaced the whole ignition system other than the wires. Coil, plugs, and distributor. Truck runs when battery is disconnected so alternator charges battery and runs other components well.

Just looking for any insight into my issue, I've never had a vehicle that Could drive for 2hrs+ then suddenly have issues. :wallbash:



also
https://cimg1.ibsrv.net/gimg/www.f15...879ae36d83.jpg

tiny cylinder on ignition coil has a random unplugged plug on it. Any ideas?

Test battery. If low, do full electrical check. Sounds like alternator failed, battery died during ride as it discharged. Happened to me once.

That's a resistor. Is the coil hot when the truck dies? I would suspect voltage to the coil could be an issue. I hate diagnosing electronics, especially when someone just fixed it.

Ricktwuhk - Battery tested out well, and I checked again this morning but with truck sitting at idle I can disconnect the battery and it still runs.

Two Dogs - Any idea where the other connections runs from so I can try and track it down? I'll check the coil temp next time it happens.

I drove it today to get emissions tested for plates and title swap (with no problems) and it came back with a 46HC rating out of an allowed 600HC. Not sure if that matters just thought I'd throw it in since that has to do with the air/fuel mixture just in case.

Do you know if the ignition module was replaced ?

https://cimg9.ibsrv.net/gimg/www.f15...aeb9e0bbd4.jpg
Ignition Coil Condenser. The other end went to the coil for filtering ignition whine/noise in the radio.
If you're not getting any RPM-dependent noise on your radio, then don't worry about it. Modern radios usually have enough bypass capacitance to reject ignition interference; factory radios are hit or miss.
Make sure that the wire that went to the condenser isn't hanging loose; this circuit is not fused.

I was told that it was replaced. I asked about it specifically after reading that old ones could malfunction after heating up.
Thank you for the idea.

I would take into consideration what brand the Ignition Module was replaced with. If not Motorcraft, I personally would go back to a Motorcraft.
Before switching over to an HEI distributor, there were a few times when I grabbed one or two from a JY and they were better than a new off-brand from the AP store.
I kept a couple of spares...one in the truck and one in the garage.

Tape and tie down that plug it's always hot while the key is on and can cause crazy grounding issues and blow fuses. From the sound of it you don't need to chase down any more gremlins

Thank you much everyone. I'm sure I'll have more questions later. It seems my AC lines were cut at the fire wall :sweatdrop: