My first thought is the coil is breaking down, try a new one, they’re reasonably cheap and if it’s not the problem a spare coil in the trunk is always a good thing.

When the key is turned to start the car,  sometimes NOTHING  happens. Turn the key back and try again, sometimes a slight hesitation then it starts, sometimes immediate start like it should normally. I checked all connections to starter, Solenoid etc. Cleaned and reconnected. Taking a trip to Connecticut  to Mustang Unlimited and exhaust place,  Don't want to get stuck!

Having somebody hit the key while you listen under the hood for the starter solenoid to kick in when it’s acting this way might be a decent troubleshooting technique, if you have the help.

Ive had the car since 1974, never a problem, its a four speed car, and it happens when the car is stone cold but eventually It will start. Will try key tap method.

Last edited by rtmjr13@optonline.net (1/25/2020 12:29 PM)

Ground-ground-ground!
6sally6

Never tried it with lights on, will try. What would that tell me?

I meant charge and oil light.

Check to make sure the tabs on start solenoid are well grounded.

Try connecting meter or test light to “s” terminal and verify voltage.  Should get full  battery voltage each time key turned to start position and solenoid energizes.

Might have to cleanup firewall connector and look closely at terminals at wire ends.  Terminals might have a non visible mechanical connection problem to wire.

Might have to clean up connectors at solenoid as well.
Start😂 with simple things first.

To save on battery draining.  You could disconnect cable to starter and perform all of these checks.  Once confident, solenoid picks up consistently...reattach starter cable.

Bolted suggestion about larger wire helps too.
I have also used a short length of heater hose to insulate from headers.
Now there are other forms of reflective heat barriers that work well.

Hope this helps.

Last edited by Nos681 (1/27/2020 1:24 PM)

I once had an intermitant run issue that escaped me for months. The engine would just quit under many different situations , once in the passing lane at 70mph. Big time  scary! The car would start right up after at times, other times would not.
 I was so pissed that at one time when it restarted and was running I got out and slammed the door as hard as I could out of frustration. Bingo the engine quit.
 I started to jiggle some wires under the hood and when I got to  the ignition feed to the spark control box. it quit.
 The culprit , a bad bullet connector.

This past summer our daily driver suddenly developed a connection break between the battery cells. You bang on the battery and the lights would flicker on and back off.
Bad things will happen if it arcs above the battery acid level inside.