Bug Fixing

A complaint received by the Pontiac Division of General Motors:
"This is the  second time I have written to you, and I don't blame you
for not answering me, because what I have to say sounds kind of crazy...
    
"But it is a fact that we have a tradition in our family of icecream
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 them my trips to the store have created a problem.  You see, every
time I buy vanilla ice cream, when I start back from the store my car won't
start. If I get any other kind of ice cream, the car starts just fine...
    
"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 dinner time,
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, the man
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
toward 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 find the flavor and get checked out.    

Now the question for the engineer was why the car wouldn't start when it
took less time.  Once time became the problem -- 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.

Often, we must look deeper than the obvious to find the real problem...