Can a loose alternator belt effect gas mileage?

[Spoolin4Ever]

My alt. belt would squel a little on startup, and when taking off from a start. Lately I noticed gas mileage is a little lower then normal, and idle dropped to 600 RPM.

I went and had the shop that did the alt. tighten the belt. Now the idel is about 850 or so (maybe it's just doing that to get the battery charged up?).

I am simply curious on other people's experience. Can a loose alternator belt cause poor gas mileage?

Thanks..

 

[mn95TSi]

possibly not spinning the alternator fast enough was affecting power to your ignition, resulting in poorer combusting.

-alex