186,000 miles on my 4.2 F150 2wd shortbox with auto trans.

I recently started keeping the truckʻs gas tank full instead of running down to E. I use about a half tank a week, today I filled up

with 12.167 gallons (to first pump click) in fact I did the same last week. My trip odometer was 184.7 miles.

Does 15.18 mpg seem correct?

Let me know what you guys get MPG wise.

 

Yes that's correct.

Best I got with mine was 19.2mpg. But now with a ton of in city driving (put on roughly 250 miles per week) I get about 9.8-12mpg with a mis-fire in number 5. But this is with a 5.4L not a 4.2. One thing I have learned was never run the tank down to E...it burns out the fuel pump much faster especially Walker brand. Best keep it at 1/4 tank or a bit more to keep the fuel pump at least covered in fuel so it won't burn out.

 

mine is 02 with 174k miles.. 4 x 4. short box.. 4.6L.. i get 12/13 mpg. crappy.

yours sounds correct for what you have.

 

I just rebuilt my motor and a test on the interstate reveals
65mph level road with cruise control = 20 mpg, but, that's with a newly rebuilt motor.

 

I'd run a can of SeaFoam in the tank after a fill up then check the next tank numbers. The SeaFoam will break down a bit of carbon build up in the engine which may help combustion a bit.