"Koopas Ly" wrote in message
om...

The only time that fuel is set to one particular tank is on the
ground. I've never used fuel from only one tank in flight. Why would
someone do that?



Some models of 172 *require* you to select a single tank
above 5000', due (supposedly) to vapor lock problems.

Check your POH.

--
Dr. Tony Cox
Citrus Controls Inc.
e-mail:
http://CitrusControls.com/