Well, after thinking I had addressed the electrical gremlins on my 1973 SB, new problems pop up to keep me from driving the car.
The latest problem: I get in the car the other day, and it won't start. It cranks just fine, battery is fine, but no start (after being very reliable before). After some trial-and-error, this is what I have figured out so far:

1. With the four-way flasher installed in the fuse block, the car won't start, and the hazard lights are always on and cannot be shut off with the steering column switch.
2. With the four-way flasher pulled out of the fuse block, the car starts fine. But pulling out the flasher also kills the turn signals, so that is not a long-term solution. Also, the arrows on the dash that indicate the turn signals light up while the brake is applied.

I am guessing I have frayed/crossed wires or something behind the fuse block. It seems like something is robbing power from the coil if the flasher is installed.
Not sure how much this might play a role, but I have a PerTronix electronic ignition system with a wire running from the center of the fuse block to the coil. But that looks fine. And the car does start without the flasher installed.
I gather that pulling the fuse block to inspect the back is a real PITA, so I'm hoping someone has had this problem and there's a simple fix!

 

What circuit is your Pertronix plugged into? Can you post a clear picture of the fuse box?
Cheers, Greg

 

That sounds like electrical gremlins.

But first, I gotta ask, do you have any LED bulbs in your car?

 

First point to make is the PerTronix electronic ignition system does not require a separate wire to be run for a power source.

https://images.carid.com/pertronix/p...structions.pdf

B. Alternative Installation: The Ignitor II can also be installed in applications retaining
the ballast resistor or resistance wire.

What happens when you disconnect the positive (+) lead from the coil and install the 4-way flasher, are your lights still screwed up?

 

Do you have a alarm system on the car ,sounds like you have a bad ground or you crossed over to a kill for the alarm system
make sure the petronix is plugged into a constant 12 v source if its plugged into the flasher you robbing the system of 12 v and it will never run right

 

Thanks for the suggestions!
There is no alarm on the car.
I don't have any LED bulbs.
The wire for the PerTronix Ignitor III is plugged into the lower central "IGN" terminal in the fuse block. (I will try to get a picture).
The setup worked fine for months, then all of a sudden... which sounds like a short or crossed wire to me. Something is providing the flasher with constant power.
I will investigate this weekend and if I discover anything, I'll pass it on.
Cheers!
PS I just looked at the fuse block quickly... and I noticed that the IGN terminal is next to the fuse for the hazards. I wonder if this is really simple and something has come loose and is making contact with another circuit. A simple fix would be great!

 

This is from a Late 1977 so your layout is different but you should get a idea how your fuse panel is laid out inside.
There are actually 2 sides to the fuse panel
A HOT always side (Buss Bar #12)
And a Switched side (Buss Bars #13 #14 & #15)
Looking at a 73 fuse panel the IGN cavity is most likely powered by the DIR. SIG. BACK UP fuse.
Check power to the IGN cavity with Ignition Switch in ON and Start Positions.
I don't think your Hazard Flasher has any relationship with your IGN cavity as the Hazard Flasher is HOT always, as long as the Stop/Hazard fuse is good.
If your DIR. SIG. BACK UP fuse is indeed the power source for the IGN cavity, carefully clean the fuse socket(s) and might as well put a new correct fuse in.

 

I'm wondering if there is a short from In turn signal /4 way flasher switch or somewhere in the colomn down to the harness. I've seen similar symptoms and that was the problem.