My Mustang won't start
Preventative Maintenance
Getting a Mustang that won't start to start is a process of elimination. The good thing is these old cars are pretty simple compared to the newer ones. Pretty basic machines to deal with.
Before I get into why it won't start, let me recommend you keep your Mustang in top shape to prevent such problems. And if you do have a starting problem, at least you'll have a good idea of what it not causing the problem. Keep a good set of wires, plugs, fresh gasoline, points and condenser in it. I also recommend a hotter than stock coil. Let's talk about a couple of issues here.
1) The ignition system - Keep your ignition system in top shape all the time. Replace your condenser periodically just because. They do go bad and that is a tough problem to diagnose. Also replace your distributor cap regularly. The carbon points wear away resulting in bad spark. I actually had the center point break off once. The car would turn over, but it would not start. Try to figure that one out. And it was a Saturday night and I was in a strange town. I started carrying a spare cap. Plug wires wear out, too. I replace mine every couple of years. Cheap insurance. Same thing goes for the points. Points were, dwell changes. I finally replaced my points with a Petronix electronic ignition and eliminated the problem totally. I recommend electronic ignition. And change your plugs periodically. When I drove my 66 Mustang Coupe daily, I changed the plugs at least once a year. My Shelby gets new plugs every couple of years.
2) Gasoline - Gasoline starts breaking down after 30 days. I recommend adding a gasoline stabilizer if the car is going to set for more than 30 days. The worse case scenario is the gas in your carb turns from a liquid to a solid. I hate to admit that I allowed that to happen one time. My car set for almost two years due to where I was and what I was doing. When I finally got back to the car it wouldn't start. It would turn over but not fire. On inspection in the carb jets I could see it wasn't feeding gasoline. I took the Holley to a recommended specialist. He called me back and wanted to know where this carb had be setting and what all the gunk in it was. I was embarrassed to tell him it was gasoline that got real old. He had to soak the carb pieces to clean it out. The moral is use a fuel stabilizer if the car is going to set and start it periodically.
3) Change the oil in your car each spring. Again cheap insurance. Oil can collect moisture from setting all winter. If you were driving it, allowing it to heat up daily the moisture will go away. This won't keep it from starting but it can make your engine last longer.