So I am brand new to this website. I just bought a 1997 f150 5.4 4x4 auto with a 6inch lift and 35s. It also has dump off exhaust. I am wonder what the size of the tank is. I have calculated 8mpg off a 22gal tank and I was also wondering how to get better mileage.

 

I think my 97 has a 25 gal. tank.

 

8 sounds extremely low, even with that lift and tires. The size of the tank is irrelevant when checking actual fuel mileage (miles driven/actual gallons used), assuming you are checking it properly. I can get 8-9mpg towing my X,000 lbs toy hauler. You've got something else going on here if your math is correct and it's really that bad.

Normally, a thread like this would warrant a smart @$$ comment like "the only way to get better mileage from this truck is to sell it and get a Civic". However, that's reserved for guys getting a normal 13-17 mpg and wanting more. You need to fix a problem first; whatever it may be. How does it run?

 

Is your odometer corrected for the oversize tires? Do you know for a fact what the (differential) gear ratio is?

The lift and big tires are both contributing to bad mileage, as is the goat **** California gas. If you are using Costco or Arco, you will never get good mileage, that stuff is terrible.

 

heck my 97 is gettin a shade over 11 on e-10. Try changing plugs, making sure gear ratio is matched to tires, and or get the odometer corrected. As Glc posted, use decent fuel...

 

should be 22g?

 

23.

 

If he has stock gears, especially 3.55's running 35's with that lift, I could see 8-10mpg in town. You need to first make sure your speedometer is corrected with the bigger tires, if that has not been done... you will be off on your calculations. You can get your mpg a few ways. Like galaxy said, the best way would be to figure how many miles driven per gallons used. Figure an average based on a full tank so just top off, drive until below a 1/4 tank then top off again, measuring how many gallons were used.

I'm sure it has a few miles on it being a 97. Like mentioned, consider your maintenance and make sure it is running good. I'll bet with just a good plug change, TB cleaning, fuel filter change, hose and vacuum system inspected, pcv valve and sensor cleaning you bump your mileage up 1-2mpg.

 

You may want to scan the OBD2 for codes. Does the CEL work? If it doesn't come on when you turn the key to ON, the previous owner may have pulled the bulb.........

 

I just bought the truck two weeks ago and had it fully checked out by ford, les schwab, and my altec mechanic, they all said everything checks out. The only thing I am not sure about is the gearing.

 

use a GPS. see how far your speedometer is off..