We recently purchased a 2020 F-250 CC with 6.5' bed. It has the 34 gallon fuel tank. We have the 7.3L engine. Is it possible to install a larger fuel tank on this truck without affecting the warranty? I have been unable to find any information regarding a larger tank for the gas engine. I have found alot of information regarding the diesel engine. We were recently towing our travel trailer and got about 8.5 mpg. The truck has just over 1,500 miles so I would hope this would improve over time. Just wondering if it is even an option to get a larger fuel tank. I did see that the 8 foot bed has the option for the larger tank. Thanks.

 

The wheelbase is an important dimension to consider. Don't know if they are different or not.
I believe you might have the incorrect engine size listed and that might contribute to the difficulty.. Maybe should be 6.7 if diesel.
Regarding warranty, check with the place you purchased it.

 

The truck has the new 7.3L gas engine that Ford has as an option on the 2020 Super Duty. Just wondering if anyone has ever installed a larger fuel tank on a F-250 gas truck.

 

From a warranty point of view I could see issues if something happens with anything immediately connected to the tank, the fuel lines, the electrical connectors, the pump itself. Keep in mind that this will not void warranty on anything not related to the fuel tank, still has base warranty for engine, trans, body, suspension, ect.
Lets say that you have running issues, issue ends up being the fuel pump is bad/damaged, dealer tech notices its not a stock fuel tank, that raises the question of did the customer cause damage to the fuel pump when swapping it over to the larger fuel tank, it would depend on the dealer but they may decide to document that with ford and then ford would have reason to declined covering the fuel pump.
Also if you get a larger tank you will have to get the ford program to adjust your distance till empty.
If you do get a larger tank I would make sure that the company has a good reputation and what the warranty is including who pays for shipping the faulty tank back should it be requested.
Personally I would recommend one of those aux fuel tanks that go in the bed.