"This is the second time I have written to you, and I don't blame you for not answering me, because I sounded crazy, but it is a fact that we have a tradition in our family of ice cream for dessert after dinner each night. But the kind of ice cream varies, so every night, after we've eaten the whole family votes on which kind of ice cream we should have and I drive down to the store to get it."
It's also a fact that I recently purchased a new Pontiac and since then my trips to the store have created a problem. You see, every time I buy a vanilla ice cream, when I start back from the store my car won't start.
I want you to know I'm serious about this question, no matter how silly it sounds: "What is there about a Pontiac that makes it not start when I get vanilla ice cream, and easy to start whenever I get any other kind?"
The Pontiac President was understandably skeptical about the letter, but sent an engineer to check it out anyway. The latter was surprised to be greeted by a successful, obviously well educated man in a fine neighborhood. He had arranged to meet the man just after dinnertime, so the two hopped into the car and drove to the ice cream store. It was vanilla ice cream that night and, sure enough, after they came back to the car, it wouldn't start.
The engineer returned for three more nights. The first night, they got chocolate. The car started. The second night, he got strawberry. The car started. The third night he ordered vanilla. The car failed to start.
Now the engineer, being a logical man, refused to believe that this man's car was allergic to vanilla ice cream. He arranged, therefore, to continue his visits for as long as it took to solve the problem. And towards this end he began to take notes, he jotted down all sorts of data: time of day, type of gas used, time to drive back and forth etc.
In a short time, he had a clue: the man took less time to buy vanilla than any other flavor. Why? The answer was in the layout of the store. Vanilla, being the most popular flavor, was in a separate case at the front of the store for quick pickup. All the other flavors were kept in the back of the store at a different counter where it took considerably longer to check out the flavor. Now, the question for the engineer was why the car wouldn't start when it took less time. Once time became the problem and not the vanilla ice-cream, the engineer quickly came up with the answer: "Vapor lock". It was happening every night; but the extra time taken to get the other flavors allowed the engine to cool down sufficiently to start. When the man got vanilla, the engine was still too hot for the vapor lock to dissipate. And this gave rise to the study on the Flash point property of the fuel used and ways to standardize and control it.