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7.3 poor fuel economy

17K views 7 replies 6 participants last post by  Zaairman 
#1 ·
so i bought a 99 f250 7.3 recently, and i noticed that i have been only getting 11 or 12 mpg on the highway... the truck is bone stock. so im wondering what could it be? I know that i should change the fuel filter but ive been at school and ive been busy. im off tomorrow and ill probably get one then.. i have those bfg all terrain tires that are pretty far worn and i figured that could also be the problem since they are wide and create alot of rolling resistance. what about an intake or exhaust? :wtf
 
#2 ·
Your tires could cause issues, but a new fuel filter probably won't hurt.

Neither will an intake or exhaust system.

Or an economy tune.

And a light foot.

I get 20.9 mpg avg with mine all-told (calendar year 2009 and holding steady for 2010) with those simple changes + a bed cover and biodiesel (no more than B20 - mostly B5 these days).

Is yours a 4wd? If so, check the hubs to make certain they aren't locked and check your brakes to make certain they aren't dragging.


prt
 
#3 ·
Something isn't right... or you're doing 90 MPH on the highway and driving like a banshee. How are you calculating the mileage?
 
#4 ·
make sure your tire pressure is right also. I had some pretty low milage a few tanks ago couldnt figure out why then I decided to check my hubs and I had them Locked from one of the few times I used my 4x4 lol.
 
#5 ·
im usually cruising at around 65 mph and im pretty easy on the throttle
 
#8 ·
How are you calculating fuel mileage? Do you fill the truck up ALL the way til you can see standing fuel in your filler neck?

You don't have one of those Gray CMP/CPS Units do you?
I do in mine. Last tank was just shy of 17 MPG. Lots of back road driving here in the Ozarks...which means lots of big hills.
 
#6 ·
yep, that's low

My truck has never, never got above 18.5 mpg. In defense, I do live at 6,500 feet and there is a 1,000 ft. drop in altitude between me and work.
Winter diesel blends usually drop my mileage about 2 mpg.
That said, I have been religious about tracking my fuel for the past 2 years and currently see 15.2 mpg average for that time. This includes winter, summer towing of my 7.5 k lb tt and 80 to 90 mph trips to Ill.

Yeah, I'd love to see 20 +. Realistically, 16 summer, 14 winter, 13.5 towing. Don't think my #s are too far from the norm.

jer :cool:
 
#7 ·
You don't have one of those Gray CMP/CPS Units do you?
 
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