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I have an 03 Z71 Tahoe and I found this electrical device next to the fuel filter. The fuel line from the filter goes directly to this device and then a second line comes out of this device and goes to the fuel rail. Does anyone have any idea what this device is or does?

Looks like a fuel composition sensor, it tells PCM the ethanol content of fuel. Your truck is e85 compatible.

Quote:

Originally Posted by 4x4toy (Post 6360683)

Looks like a fuel composition sensor, it tells PCM the ethanol content of fuel. Your truck is e85 compatible.

Ok thanks. Wasnt sure what that thing was, had never seen one before and I have been under many of these trucks. Was curious because I am trying to figure out why my mpg's have been slowly dropping for over a year now. I went from 17-18 down to 12.8-13.2. Wanted to know incase it could have any effect on mileage.
I know its E85 compatiable and tried that crap for two tanks back in 2007 and will never do it again. At that time the E85 was $1.99/gal and unleaded was $3.09/gal and while the engine ran smoother and seemed to have a bit more power below 3000rpm the trade off in mpg was not worth the price savings at all. I went from 17-18mpg down to 8-9mpg and used two tanks in one week effectively negating any cost savings.