# stupid question about gas pumps

**URL:** <https://boards.straightdope.com/t/stupid-question-about-gas-pumps/164371>\
**Category:** Factual Questions\
**Created:** [March 26, 2003, 9:16pm UTC](https://boards.straightdope.com/t/stupid-question-about-gas-pumps/164371 "2003-03-26T21:16:11Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![horhay\_achoa](https://avatars.discourse-cdn.com/v4/letter/h/ccd318/32.png) [@horhay\_achoa](https://boards.straightdope.com/u/horhay_achoa)\
**Post date:** [March 26, 2003, 9:16pm UTC](https://boards.straightdope.com/t/stupid-question-about-gas-pumps/164371/1 "2003-03-26T21:16:11Z")

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Why is it that if you pre-pay for gas the pump goes extremely slow the last 15-25 cents of your purchase? Just for fun I have tried to time it so that I stop the pump right on a certain amount, and it isn’t that tough. Why can’t the pump stop itself right on the amount you purchased without slowing down first?

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**Author:** ![Penumbra](https://avatars.discourse-cdn.com/v4/letter/p/9f8e36/32.png) [@Penumbra](https://boards.straightdope.com/u/Penumbra)\
**Post date:** [March 26, 2003, 9:54pm UTC](https://boards.straightdope.com/t/stupid-question-about-gas-pumps/164371/2 "2003-03-26T21:54:13Z")

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I’ve often wondered this too. Here I am pumping, pumping away and all of a sudden the pump slows down to a screeching near halt for the final 15 cents. I’ve always assumed its was the manufactures way of saying, “Hey dickhead, you don’t get to leave yet… go inside and buy some crackers.”

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**Author:** ![WillGolfForFood](https://avatars.discourse-cdn.com/v4/letter/w/82dd89/32.png) [@WillGolfForFood](https://boards.straightdope.com/u/WillGolfForFood)\
**Post date:** [March 26, 2003, 10:01pm UTC](https://boards.straightdope.com/t/stupid-question-about-gas-pumps/164371/3 "2003-03-26T22:01:51Z")

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Try this: put a mark on a water glass about 75 percent of the way up. Now fill that glass to the mark using a pitcher full of water. Don’t slow down as you near the mark - just pour at a constant, high speed and stop at the 75 percent mark.

I suspect that the automated pump has a similar problem.