My 66 Mustang quits running after about 5 or 10 minutes. If I am driving down the road it restarts and works fine after that. If it happens at a stop sign, I have to restart it. It starts immediately and works fine after that. If I park it for a while and start it again the same thing happens. New wiring harness and ignition switch 4 years ago. Mallory electronic distributor and new Pertronix coil. Fuel flow and spark are good. 289 4V with C4 automatic. What should I check next? I hate intermittent problems. Have lost all faith in this car. Purchased in 1992 and has been great up to now.
Exact same thing happened on my 67 Fastback. After much consternation, it turned out to be the ignition module inside my new Mallory distributor. When I checked it in my driveway using the Mallory diagnostic check, it checked fine, when it heated up after driving, it didn't. Change the module (not cheap) and it should be fine.
I'm not familiar with that particular car so this is generic information.
If a carb engine, sounds like the choke might be sticking at one particular point in it's travel.
I'm assuming this car doesn't have an EGR valve !
But that's another typical "stall once and go" fix.
When it fails does it sputter and die, or just *turn off* like someone turned the key?
If it just turns off, I would suspect an electrical problem. Ignition switch and wiring etc.
Sputtering and dying I would suspect fuel delivery.
If EFI, the hall effect pickups/coils in the distributor are high failure rate items for most cars, but they generally fail when hot not while heating up. An intermittent one will drive you crazy.
Still, worth a check.
Will it do it only while driving, or when sitting at idle in the driveway as well?
Intermittent failures are the bane of my existence!!
I once had a car (EFI) that would intermittently lose power or turn off when making sharp right hand turns, like exiting a highway. I went crazy trying to fix it until I noticed that the coil (a cylindrical model) made sloshing noises when I picked it up and shook it. Turned out that the die-electric fluid had mostly leaked out and a sharp turn was enough for it to give the ignition system fits. Took me a couple of weeks to find it because it didn't always fail.
I would reseat all connectors, wiggle wires while car is running etc and see if you can zero in on it. Sounds like it's going to be a long haul, but you'll get it!
I had a 73 Ranchero GT that did the same thing two different times. The first time was an intermittant ignition coil failure. The second time I had some crap in my float bowls that would block the ports. Good luck! You find the problem, the older cars are so much easier to troubleshoot, that's why I went with a '72 mach 1. Dave
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