There's something seriously wrong with an I6 truck that only gets 10mpg, in general you would have to be using it for snow plowing or something like that to do that bad.
Does the truck get the same fuel milage on both tanks? It should so if you're not that would indicate a fuel transfer problem.
As indicated check codes and fix anything that comes up, and if the O2 sensor hasn't been replaced in the last 60k put one of those in it too.

 

i set the cruise right after it hits overdrive thats why i get so good of mpg but its kinda slow

 

Still not biting man..

31's would make the OD ratio even "Shallow-er"...Meaning the truck has to kick down to passing gears pretty much any time you get on an incline..Of any sort.


As I said earlier; If you've not re-calibrated your speedometer, etc for the 31" tires...Your mpg readings won't be accurate.

 

dont blame you most people dont believe me until they see me fill up and run the numbers

 

Not only this, but your truck will suffer from "poor performance" because of incorrect load calculations/values sent to and from the PCM.

My 94' 4X4 averages 15-17 MPG.
I'm a grandpa and I drive like it too.


Bob

 

If you're looking for someone to call out, try taking a look at this thread...
FORDSIX PERFORMANCE • View topic - Coast-to-Coast: Mega-MPG

And this one...
FORDSIX PERFORMANCE • View topic - Bumper mod, spare relocate, etc., = 4mpg bump

But I also don't get why people often suggest a mileage improvement by going from a 3.08 to 3.55. Clearly you're going to turn more RPM doing that. If you're in 5th and need some more gear, why not just downshift to 4th, no? Otherwise, drive it like a Peterbilt for best mileage.

 

That's true BUT if he never re-calibrated and is figuring by his odometer he would actually be getting better gas mileage than the math would show.

Maybe he re-calibrated and went too far the other way.

 

30+ mpg from a 20 year old truck? Exhaust, electric fan, tonneau cover and a wooden bumper to achieve these numbers? I guess I have been doing everything wrong.

Either he doesn't know how to calculate MPG, or he's done something MAJOR and isn't telling... Like a Cumming 4bt swap possibly...

 

right.3.08 gearing beats 3.55's all to heck for economy.
you swap to the 3.55's for increased in hauling/towing grunt power,or to compensate for larger tires.economy suffers by doing this swap.how much it suffers depends on how fast you normally drive.
some claim the lower gearing will be better for city stop and go economy,but i didn't see any increase when i did the swap.thankfully since i drive slow/no hwy,economy didn't go down either,but most people here don't drive as slow as i do im sure lol.so no doubt as general rule,3.08's can only be beat by that silly rare 2.73 option or whatever it is.-iv never seen a f150 with this gearing personally.im sure that's getting way out of hand.a slush puppy 55mph + hwy cruiser only type truck.

 

tehh he he but besides a 3g and an e fan its all stock

 

you should be getting better then 10 with your 4.6. And Correct on gearing. re-gearing will do nothing to IMPROVE your mpg efficiency. If anything it will make it worse. Anyway there is something wrong with your truck other than tires and gears...

 

And the bumper conversion was worth 4MPG all on it's own!

 

Looks like I'm going to Home Depot... lol

Honestly, how can one think a REAR bumper makes that much of a difference?

 

Maybe his previous bumper was actually a parachute?