I have a 1997 f150 with the 4,6... auto tranny and 4x4 ... go it used and shortly
I had to put a new engine it it, got a refurbished, remanufactured engine...

my MPG is about 10 - (it has been YEARs since I owned a gas engine and 1/2 ton truck) is the about right?
we did not replace the injectors - just an FYI

on edit:
tire size is 285/75/16
rear end is 3.55
speedometer is off about 10-12%.

thanks
Al

 

Are tire sizes stock?
Confirmed accurate speedometer/odometer?
What gear ratio?
10mph is considered low. I would expect a 4.6 on a stock truck to perform better. I've never owned a 4.9, however it's hard to know why your MPG readings are lower than average without knowing the vehicle specifics I asked for.

 

Bull dawg, according to Natural Resources Canada, your vehicle is rated at 13 mpg (U.S. gallons) in the city and 17 mpg on the highway. So if you're only getting 10 mpg, I think that something ain't right. While I always take the stated ratings with a grain of salt, my '99 4.2l rwd mileage is actually very close to the NRC rating (14 city and 18 highway). Of course, there are many factors at play, such as summer vs winter and individual driving habits, but if you're only getting 10 mpg I would look into it further. Best of luck.

 

With my blue 98 with 4.6 and 355's I can get up to 18 on the highway, but overall it's more like 14-15. My oem tire shows 255/70r16 but I run 265/70r17s most of the time. I reset my speedo to correct %ages and it is about spot on.

If you have a 4.6 and only getting 10 mpg, then something is off. Running 285's is much more than the door tag shows for correct tire size. The bigger the tire, the mpg goes to hell quickly.

 

Either regear to compensate or step down to 255/70/16 or whatever the upsize was for 4x4s for ‘97.

Sure, the speedometer is only off 10% or thereabouts, but that’s fewer RPMs the engine is spinning and that much farther out of its powerband plus the gas pedal gets massaged harder to shift down a couple gears to pass anyone. 210 horsepower 4.6s need all the help they can get.

Or live as is.

 

Thanks Gentlemen
it mostly a hunting truck so the MPG isn't a big issue, I reckon its the tires mostly, the price we pay to look cool!

Al

 

I'm getting 7 mpg on a rolling average of the last 10 fillups - close to 12 mpg overall since i've owned the truck 15+ yrs.

Factors affecting my low mileage:

• it's winter
• my commute to work is 1.8 miles one way
• i like to warm up my vehicle in the morning
• i plow with it
• i live in Maine, cold winters, lots of plowing