Terrible fuel mileage

[litletex]

05 F250 6.0 FX4 superduty with 80,000 miles on 37" pro comp tires and 6" lift is only getting 9 miles to the gallon city and on freeway I get 11. I have talked to other diesel owners and they all say they get anywhere from 14-18....any advice would be helpful

[DoubleDpsd]

what's the status with your fuel filters?

[R.KV*22*]

Your fuel filters seem like they're clogging the flow.

[litletex]

Thanx for the info....will check it out and replace the filters. First time diesel owner so little hesitant to do anything on my own but what the hek.

should such a simple thing really get me in the double digits in fuel or is there anything else I should possibly consider in addition to this?

[Evil Eye]

to the org, Litletex. Fuel filters certainly could cause this problem. These trucks live and die (quite literally) based on the maintenance or lack thereof. A good rule of thumb is to have your fuel filters replaced every third oil change (~15,000 miles) if your running dino oil and every oil change if your running synthetic.

Oh, and I've gotten better than 20 mpg highway with my SCT tuner. You might consider that, but it will also require several other mods to ensure you don't blow your engine.

[Dave]

I see you are running 37 inch tires and a lift also. what gearing do you have in your rear end?

[Clay Henry]

Filters clogged won't effect fuel milage, they effect fuel pressure and low fuel pressure - below 40 psi is a bad thing...that will knock out injectors which is by far worse that bad milage.
I would suspect your milage issues are from the huge tires/lift and possibly to high gear ration on the rear end.
If you just got this truck used its a good idea to change the filters, all the fluids, etc just so you know they are good and stick to a maintenance program thereafter.