Vapor lock?

I went for about a 50 mile drive today. The ambient temperature is around 87 degrees. The car ran fine, with the water temperature hovering between approx. 180 to 195. As I got back into traffic approaching home, I noticed that the car seemed to be losing power slightly, and the engine note was "off". Then I had to stop at a traffic light for about two minutes. At this point, the temperature gauge indicated slightly higher than 195. For the next mile or so, in traffic at about 40 mph, the car steadily lost power (and sounded sick) until it died completely. I'd say that it definitely felt like a fuel delivery issue, and I did notice a somewhat strong gasoline smell. I turned on the flashers and was able to coast onto a side street and switch off the ignition. After less than a minute, I turned the key and it started right up. I drove the rest of the way home (about another mile and a half at low speed) with the car seeming normal.

My first thought was vapor lock, but I guess it could be the fuel pump also.

 

Thanks for reinforcing my suspicions, Tony.

I've experienced vapor lock in a number of older vehicles (most recently a severe case in an Alfa spyder during a Lemons race), and that's definitely what this felt like. Interesting about the fuels, though I doubt that's the culprit in this case as I live in a mild climate and had just filled up prior to the drive. I do wonder what suddenly caused it to happen, as I have driven the car in hotter weather than this without any issues, though this is probably the warmest in a while. Hmmm, would ethanol added to the gas increase its volatility?

Well, well, well... A quick Internet "study" indicates that ethanol as an additive does indeed significantly increase the volatility of gasoline. Here's one tidbit:

"Oxygenates, primarily ethanol and methanol-cosolvent mixtures, have excellent octane blending values. However, alcohols complicate volatility blending. The seriousness of the situation is verified by trends that show a steady rise in the volatility of gasoline reaching the market place. As discussed previously, EPA has focused on gasoline volatility from the standpoint of readily available hydrocarbon emissions reductions."

So, this could be the warmest day that the car has been driven with the latest, higher ethanol content gasoline.

 

Thanks. Nope, the Dinoplex was replaced by another unit roughly 20 years ago, and then an MSD unit about a year and a half ago. Anyway, it felt like fuel, not ignition. I suppose it could be ignition. That would explain the quick restart, which does not jibe with vapor lock.

 

That's interesting, Jim. It sounds almost exactly like my issue, except that my car started back up after less than a minute. Like you, I've never had the problem until now. I didn't get a chance to drive the car this past weekend as the weather was rainy.

I have done some more checking, and it's generally acknowledged that the ethanol being added to gasoline exacerbates the problem by increasing volatility.

 

This is really weird. Yesterday, I had almost exactly the same thing happen again, not quite one year later. Not only that, but the car died on the same stretch of road and I had to pull off onto the same cross street. Five minutes later, it started and drove normally.

 

Yes, my 1974 GPS which consists of a folded-up map in the door pocket!