Stop killing your car at the gas pump!

I had an idea for a blog post yesterday while sitting in line at Sam's Club to gas up. The gentleman at the pump right in front of me was filling his SUV and I watched to see if he would "over-squeeze". Yep, he did; in fact, after the initial cut off, he spent another couple of minutes squeezing and hitting additional shutoffs. On the fourth squeeze (yes, four extra squeezes!), I saw fuel spill out of the filler so he had, in fact, filled it right up to the top.

So, simple question: When you fill up, do you stop on the first "click" or do you give it a couple of extra squeezes on the handle?

Yep, that's what I thought and you are killing your car. Oh, not right away, and maybe not during your ownership, but eventually it will catch up. One extra squeeze will probably not be a problem, but don't get carried away with getting 10¢ extra gas in the tank.

Modern vehicles are not made to have their fuel tanks filled up right to the brim; on the contrary, they need to have a little "breathing" room. Literally. The vapors in the tank are pulled out via the Evaporative Emission Control (EVAP) System whose primary component is a canister of activated charcoal.

When you overfill the tank, you run the risk of contaminating this canister with raw fuel instead of vapors. This will eventually lead to failure, the average cost to fix being about $500.

Here's a simple diagram: