I know clothespins have been used for years but what is the theory behind them? I just do not understand what they would do to cure the problem.

 

Some think of them as heat sinks but at best they're actually heat insulators (insulating the line from picking up additional heat.) Then some don't care either way, they just remember seeing/using/hearing about them. The 100% cure is a rear-mounted electric pump.

 

Theory not known, however, the empirical evidence speaks for itself. Some believe that it creates a more turbulent airflow around the line.

 

I was told a story once... the newlyweds were going to have a big supper for the two families. The wife asked the husband to cut the bone off the end of the ham, so he did. And he wondered what the purpose for doing so was. A few years later and many hams also, the two families were together again. Same scenario. So he happened to ask his MIL why. She said that was what she was taught. So he asked grandma in law. GIL says she had to cut the bone off because her pan was too short to fit the ham. And so on down the line the practice went. Maybe the clothes pins are the same way. Dunno.

 

I found this answer to the clothespin/vapor lock question on a Packard (car) site:

"I have degrees in engineering and applied sciences and got one of my few A's in thermodynamics.

I collaborated with Connecting Rod Serling. What we believe happened is someone's car would not start and it was diagnosed as "vapor lock". Thinking that vapor lock occurs in the pump to carb line the owner rounded up some clothespins and put them on the line. The car started, total time 5 minutes. Actually vapor lock is in the tank to pump line but through some dark magic the clothespins on the wrong line cured it and a new "science" was born.

Then we decided to experiment. Another car had the same problem, we rounded up some pink ribbon, cut 6" lengths, tied them to the fuel line, cured!! Took 5 minutes. Next time we tied them to the antenna, cured!

Man, Rod and I were golden, we were gong to open a repair shop. Then it occured again on a day we were dog tired from all of our experiments so we downed a few Coronas (not the Toyota type). Bam, the car started after we had relaxed for 5 minutes. Better than golden, we could fix cars, get drunk, do nothing and get paid for it."

So there you have it!

 

I've often wondered if that was the "cure". Pulling over and sitting with the hood open, trying to think of a cure, probably does as much good as anything else.

 

Make sure that your new tank has either a vent line or a vented gas cap. Most new caps are not vented. Often even replacement caps for older vehicles like our are not vented.