The following puzzler was posted not long ago to the email group for Austin Healeys. It elicited a lot of responses and provided great fodder for thought as well as a good list for trouble shooting your car when it mysteriously dies on the highway or byway or dirt road or parking lot or driveway or at the concours meet!
Thanks to all who contributed. There has been a little license taken to protect the innocent.
On the way home from (fill in city, anywhere, USA), cruising at about 75 in the fast lane (eight lanes, or ten or twelve, or more from the shoulder) in morning rush hour traffic, I felt my BN1,2,4,6,7 (or BJ, fill in blank) engine STOP -- no coughs, no chuffs, just STOP. Then immediately restart. It repeated this four times in a minute, which was more than enough to make me wish I was anywhere else. I moved all the way over to the lane next to the shoulder, where I stayed for the rest of the next hour. Of course, it didn't repeat the problem. It did the same thing again in rush hour afternoon traffic that day.
We thought about it, talked about it, and came up with a theory.
Answers? Well, it turns out that there are many correct answers as demonstrated by the sometimes short and sometimes long answers which follow. All are actual experiences!
1. Our diagnosis was it was electrical, and best guess was a frayed ground wire or flex wire inside the distributor. At high speed, the distributor was held at full advance, and one of the two frayed wires shorted out to the distributor case or plate, stopping the engine. Once the engine stopped, the advance plate swung back, pulling the wire back and out of harm's way, but immediately went right back to the same position when the engine restarted and shorted/stopped again. Repeat until the wire bends enough to no longer make contact.
Carefully check both of those little wires, which have been in there bending, and unbending, for forty years or so. If in doubt, replace them. Costs about $20 bucks for the two wires and two insulators needed, but ...
2. I would have bet more on an intermittent coil/ballast resistor, due to your High-Temp rush hour situations.
3. The coil wire where it goes into the distributor cap. Sometimes the screw doesn't seat well into the coil wire.
The car was going great until I hit one of the speed bumps on the pavement. The engine died flat on the bump, starts again after the bump. This happened many times. Since I could not figure out the cause I did nothing about it. One day far away from home it died again on a bump but never came to life again. I spent at least a couple of hours beside the road examining all electrical parts connected to the ignition but could not find the fault. I had to call a tow-truck which towed me the 30 miles to my garage. In the peace of my garage I finally found the problem, eventhough it took a very long time, since I concentrated on the ignition parts under the bonnet.
It turned out to be that the lead, that shorts the coil connected to the battery master switch in the trunk, was sitting loose and that it had been able to jump out on the bumps and then someway found its way back again.
5. I had a very similar problem...it was the battery cutoff switch.
6. I had this problem several times and it was always due to a faulty condenser. It was solved ultimately by an electronic ignition and the car now runs fine. I used an Ignitor and it has been terrific.
7. Funny thing, this exact thing happened me in a BN7. It turned out to be a loose barrel in the ignition switch. The fix? Jiggle the handle (the key) and replace the ignition switch.
8. I thought the cut-off switch looked a little dicey and figured that any thief could not know about the button starter and would break off the key trying to start the Healey, so I didn't connect the cut-off switch at all. I wired the positive post directly to the frame. Thus the white/black wire was left unconnected at the battery cut-off switch in the boot..
BUT when I wired up the coil I connected the white/black wire to the + pole of the coil.
I would drive for 30 minutes - the engine would quit, I couldn't restart and I would sit and swear and then miraculously the engine would then start.... and so on for about a month. Then I pulled off the white/black wire - tied a knot in it and ever since - 7 years and 18,000 miles - I have NEVER had a repeat. The white/black wire in the boot was grounding out as it flopped around.
9. I had the same symptoms and my Healey finally died for good and had to ride home on the hook (only time in 31 years of ownership). It was the carbon pin on the spring inside the distributor cap sticking up and not dropping back down to make contact with the rotor.
I once found my carbon pin inside of the distributor cap was missing. The engine had been running with the contact consisting only of the spring. Boy did it look messy in there with all the sparking going on. The carbon tip and spring is a useful part to replace once in awhile.
11. Does your gas gauge continue to register? If the gas gauge stops registering, the problem is probably in the ignition switch. If the gas gauge continues to read as normal, the problem is probably in the ignition system (coil and distributor) and not in the ignition switch.
Big Healeys are a demanding mistress. She will get you when you least expect it!
Greensboro, N.C. 27403