Are you actually getting 19 with hand calculation? Or is that what it says on the display? I can get mine to show 18ish, but the math when I fill up shows 16 at most. The dash computer rarely gets the calculation 100‰ right.

 

What the display says. I'm about to take a drive to Salt Lake City, will top off before leaving and then top off again and find out for sure. Probably need to use GPS too, since the speedo reads 2mph fast at 60.

 

lol... now we understand.

 

Wait, this Gen of F150 has a MPG display?

 

Higher trims like lariat, King ranch and probably fx4 do.

Xlt and lower trims I don't think they do or I don't recall that they do.

It's next to the odo on my 04 lariat.

 

There are a lot of problems that could cause this. Start by scanning for codes (auto parts stores will do this for free), cleaning the MAF, cleaning the throttle body, checking tires inflation and alignment (unusual tire wear) and checking the brakes for dragging. These help to fix many cases cheaply. If no improvement, either visit a mechanic for fuel pressure, vacuum, and exhaust tests or invest in an OBD-II scanner and plan to troubleshoot/fix it yourself.

 

My 05 XLT does not have a mpg display.

 

Good point on tire inflation/wheel alignment. When I first got mine I noticed the front tires wearing really fast on the inside of the tread, indicating serious toe-out/negative camber. Was showing 14mpg on the display at the time. I adjusted the toe-out back in a lot on the driver side, and the tire wear evened out and gas mileage went up. Worth a check at least.

 

I reset the display at topoff in Jackson, and it showed 16.9 mpg at topoff in Salt Lake. Just did the math - 326 miles from Jackson WY to the gas station in Salt Lake, took 19.535 gallons to top it off. Comes to 16.7 mpg, so mine's dead-on.

And yes, I know 16.7 mpg is not 19 mpg. Interstate speed limit the whole way was 80, with a short stretch at 75 - and I drove at an undisclosed speed the whole way. In my usual AO, I do 60 to town & back, around 70 in places on the way to Idaho Falls or Rexburg - and I get around 19mpg doing it.

Currently sitting at 15.8 after that very undisclosed-speed drive back home. 😁

 

Is there any chance you got a fill up with higher ethanol content in the fuel?
That would certainly lower mpg?