fuel milage

[99 heavypuller]

i have a 99 F350 psd with a 6 speed. i have had it a very short time it has a 100 horse hyperchip. The previous owner said it got 15-18 miles per gallon, and it seems as if we are only getting 10-13 mpg. I was wondering if anyone had any ideas, this is my first powerstroke.

[MartyB]

Depending on your truck gearing, driving habits, and payload, from my experience you should expect fuel mileage anywhere from 9 to 17 mpg. My truck has 3.73 gearing, and is a fully loaded crew cab 4X4 DRW Auto. I have gotten 14-17 mpg running empty for the life of the truck. Summer fuel mileage is better by 1-2 mpg than winter. When towing, mileage varies considerably, but 10-12 mpg is typical for me.

The guy who sold you the truck may have been using the overhead display mileage, which does not work properly with a chip. Hope this helps.

[Marty]

His driving habits were different then yours... that is a likely cause for different numbers. Or like said above the guy was using the overhead display which is known to be off. OR He was inflating the #'s to make it more appealing at the time of sale!

Try driving more conservatively, don't lug the engine but keep her under 2000rpm's and the less you use the brakes the less fuel you'll use.
Hope this helps!