73 f250. Fresh 390. Everything is new. Seriously.
I had been having issues with the Mallory e something another solid state ignition I installed, so I took that out and reinstalled the points and condenser. Also have a known good mad blaster 2 epoxy coil, and a known good new oil filled coil. Truck was running fine, pulled hard, ran good, no issues.
Today tho...it wouldn't start. Seemed like same symptoms as with the Mallory. New points and condenser, because I have a hoard or them. No dice. Changed out the mad to the new oil filled. No dice. Check for voltage at the coil with key on. None found. Checked voltage while cranking engine. None found.
Hot wire from battery to + post on coil. Nothing. No spark at the points while bumping the can around by hand, or while cranking the engine.
Another set of points, and condenser, again...hoard. Same.
It did start, once, but ran really rough and pooped out. I
I have visually confirmed the lack of apart at points. Confirmed no voltage when key is on or while cranking. Also have a full tank of 93oct and visually verified fuel being shot in to carb. I have 3 ground straps on the engine. A fresh battery. All wiring is intact and clean and has not been tampered with. Resistor wire is in place and being used.
What has me confused is even with 12 volts from the battery on the + of the coil, I still have no start.
My last resort is a new switch. But shouldn't the truck still start when the coil is hot wired, or am I missing something. Please tell me I'm missing something and the switch is killed. It is the original switch, I've had it out before, last year.
Hopefully someone can guide me in the right direction. Problems like this are frustrating when it's getting cold and dark. Thanks in advance

 

It should start with battery voltage to the coil, maybe something in the wiring from the coil to the distributor is bad like a wire?

 

I checked and checked wires. The ground inside the distributor is good. The wire going from the coil to the points is new, I actually just made it. Nothing is grounding on anything. And like I said I did get an intermittent spark, enough to start the truck for a moment.

 

As far as I can see it should run, did you check the back of the switch for voltage to the coil ? Maybe the resistor wire burned out, some coils will burn out with full battery voltage

 

I haven't taken the switch out yet. It got dark, hands were getting numb. Nerves were shot.
I'll check the resistor wire out. From the coil back to the grommet everything is intact. When I did get it to start, I measured 3 volts at the coil as it was cranking over. But that's all I saw. Last week before I took the Mallory conversion out I measured voltage, and had 12 volts with switch on and while cranking. I didn't check it running at the time. I dunno.

 

It should have 12V when it's cranking but it drops (to 6-7?) after its running to keep from damaging the coil. I understand wanting to get in out of the cold!

 

Right. 12v while cranking the then resistor wire drops running voltage down to keep from killing the coil and points.
But today all I saw was 3v while cranking. I can't find a reason why I would have such low voltage or no voltage at the coil. I replaced the voltage regulator not long ago due to the old one being...old...but it did work. I even swapped it out today but to no avail.

 

The voltage regulator is only for the charging system, maybe the low and no voltage is in your switch (bad contacts) though that still wouldn't explain why it didn't start with battery voltage

 

After looking at some pics online I've noticed I have my ground wire going from the condenser screw, not going from the points screw. I wonder if that is having an effect on it. I would think it could. Out to the cold!

Eh. Disregard. I have it in there correctly already.
I didn't try starting it directly wired to the battery after I put in another near condenser tho. Maybe that will do something. Maybe the switch does have something to do with it.

 

That could be it, maybe that's shorting out the coil and points so it won't fire

 

Got it running. Looks like the switch was dead, according to some trouble shooting. So I got voltage to the points but none out of the points. The little ground wire must not have been grounded like it wanted to be. Took it out. Gently talked to it. Reinstalled. Lit right off.

 

Glad to hear it!

 

Glad you got your truck running.


As you are probably aware, the power to the coil while cranking does not go through the ignition switch. It's source is the "I" terminal on the starter solenoid. This is why you will see cranking battery voltage, and not resistor voltage, at the coil (+) while cranking.
An internal short in the ignition switch could "bleed" this power away from the coil, causing the low voltage you encountered.

You may want to double check the cranking voltage at the coil (+) and make sure you don't have another potential problem.

Hope this helps.