Just wondering because I have no idea. I just replaced my fuel pump, banjo, gaskets, fuel lines, and fuel bowl yesterday and my mileage seems amazing (fpr clogged to crap). Just want to see if I can calculate my mileage that's all.

 

Rear tank is exactly 17gal all the way to the filler neck. Front no so sure but mines a long bed and can fit exactly 19.5gal to the filler neck.

Forgot to mention that if your going to do mpg recording do yourself a favor and fill it all the way up till it doesnt fit no more that way theres no guessing if one pump filled more than another.

 

Yea I filled it up to where it almost came out. So far the average seems to be right in the 17/19 mpg. I was getting about 8 mpg with my fuel leak. I'm happy. Thanks for the info!

 

If you still have the owner's manual in the glove box, there is a section in it that gives you all the tank capacities for all the different cab and transmission configurations.

 

rear tanks is 18.2 no matter what wheel base. 19 on cab and chassis trucks
front short bed tanks are 16.5
front long bed tanks are 23, 19, 16.5(they came all 3. the 23 gallon is a plastic tank and I have ONLY seen then on 97 F350s. The 19 and 16.5 are steel and I have only seen the 16.5 on gassers)

 

Fuel tank capacity has no bearing on fuel economy calculation anyway.