So,
I filled the truck up yesterday (Both Tanks = $100 ) and took the truck on it's first real hauling mission. I had some scrap metal, A/c Condensor from a house, another coil, some gutters, and some other stuff....about 250-300 lbs plus me and my wife heading to the metal recycling joint. So by the time we got there, dropped, made 3 other stops in town, and came home, we had used about 1/3 tank on one of the 13.5 gal tanks. The way there and back was 46 miles of interstate (60-65 mph), and all the stop and go in town was about 20 miles. We got an avg. mpg of 14.8 by my calculations. Is this any good? it is a 1980 F-150 V8 302 w/ edelbrock performance 4bl, and edelbrock intake manifold. 87 octane gas, new 14" round air filter, new plugs/wires/dist. cap 300 miles ago. Tough to find factory #'s on this truck. OOOHHHH and I think it was bored +.030 back in 1994 according to some random paper work that came with the truck.

 

15 MPG in mixed driving is not too bad. Even new trucks tend to be right around that same figure.
Did you write down the mileage when you filled up? Only way to get accurate figures, is keep track of exact miles driven, and number of gallons needed to refill, over 4-6 tanks of fuel.
As for the "13.5 gal" tanks, I've never seen a tank that small in these trucks. Front is either 16 (SB) or 19 (LB) and rear is 19, factory.
You cannot judge the actual fuel used just by relying on the gauge. They tend to be a bit vague. Usually, they're pretty accurate at each end, and vary wildly in between.

 

I get right at 15 mpg in my '80 F-150 with the 300-6 engine, so 14.8 sure sounds about right for you. But I'll second that you can't count on the gas gauge on these things, you have to get your fuel measurement from the pump.

 

I use the log i got from another site to keep track of my mileage, and I'm only getting about 10.5 MPG with a 300.
Then again its also a 4X4 with 10.5 inches of rubber touching the road.

 

The 300-6 can get better than 15, IF it has economy gears in the rear end, and the right transmission combos. 15 is about right for the 4x4.

The 302 is right on the money at 15 MPG.

If you actually used 1/3 of a tank, and your truck is the one in your avatar, you actually got 10.47 miles to the gallon if you have the stock 19 gallon tanks.

But as the people above said, you can't rely on the gas gauge for proper measurment. Use the pump and top off method.

You can't rely on the odometer either. The odometer can be up to 1/10th of a mile off for every mile, from the factory. That's only about a 1 mile an hour error, but that also means it can be off 10 miles in every 100. Then couple the fact with different size tires than what was on it from the factory and it can be way off.

 

14.78260869565217391304347826087 MPG so far (204 miles 13.8 gallons of fuel)

4.9 <500 miles on it, and a 1 bbl.
f150 with ~ 400 pounds of toolbox and crap in it at the moment. a fair %50 mix of highway / in town.

 

14.8 MPG is pretty good for mixed city/highway. Best I've seen in mine is almost 17 MPG with 351w in a Supercab F-250 4x4 with C6 and 3.55:1. That was 90% highway at 75 MPH. I'd say your MPG is fine. Might be able to make some improvements if you want to be on a mission, but really you're not doing bad.

Also, what Rogue said about the tanks You got either a 16 or 19 gallon front tank depending if short bed or long bed,and rear in either is 19 gallons. Wouldn't affect your figures though.

 

14.78 is good for an engine not even broke in yet.

 

But what. Mine is 4x4 5.0 1980 and I struggle to get 5 mpg with driving careful something must be seriously wrong with mine 😂

 

What motor, gears, tires and are you sure the speedo is on the money?
If it is not clocking miles right then everything will be off.
Also over how many tanks is that 5 mpg?

I just got my 81 F100 flare side 300 six / T18 / 2.75 rear, stock size tires on the road and the first fill up after 125 miles came up with 12.49 mpg that I think is kind of crappy when my 02 Durango w/5.9 v8 gets about 14 mpg with AC on.
Half that 125 is high way at 65 - 75 mph (going to work) and city roads w/stop lights at 45 mph (home from work).
Again first fill up so cant say that is on the money but I know the speedo is as I used my truckers GPS that also has MPH and they matched when I tested when I first got truck on the road.
Dave ----