Aux fuel tank on F-250 6.2

As I remember, gravity flow between the tank and engine for gas is illegal and that the outlet port for any tank must be higher than the inlet, therefore a pump becomes mandatory. But wasn't sure about gravity flow between tanks. So here is something from the TransferFlow web site.

1) The 1990 Clean Air Act states that an individual owner of a vehicle may modify his fuel system only if it complies with all federal regulations. If he does not, he will risk state and federal penalties.
2) When an auxiliary system is added to a gasoline powered vehicle, the fuel must be drawn through a pipe at the top of the tank. Balance lines or tanks in series so that one tank supplies another is not permitted. Gravity feeding from one tank to another using a balance line is illegal for all systems except ICC diesel systems.
3) Replacement systems are acceptable as long as they meet the previously discussed regulations.
4) Should non compliance with FMVSS or the 1990 Clean Air Act be discovered, the owner would be liable for civil penalties up to $2,500 for each violation. Also, the Federal Clean Air Act requires manufacturers to exercise more care in their product applications to avoid violations of the law. Violations can carry penalties up to $200,000. For example, adding a fuel system that does not meet provisions for proper emissions control could be in violation of the Federal Clean Air Act.
5) Fuel line routing should allow for a minimum of 3 inches of clearance from the exhaust system or else a metal heat shield must be provided.
6) Fuel lines should never be routed on the outside of the vehicle body.

A larger replacement tank or a "refueling" tank are your best options. Advantage of a refueling tank is that other than having a secure mounting system, it only needs 12V connection for the built-in pump, so removing the tank would be a very simple and safe task with little risk of a fuel spill.

My thinking is/was:

Using something like a 5th wheel track system where I could install the tank on a as needed basis,and then when I need the full length of the bed, just remove the aux fuel tank when were not traveling.

I think I could find a good used reefer tank from a salvage site, then have it professionally cleaned on the inside for way less than the cost of a new one. I was just using this specific picture for illustration purposes.

By looking at the site by the time you buy the tank, 2 cradles and the straps you could by a nice tank tool box combo.

I have a aux tank combo set up with a pump that pumps into the main tank and yes it's a sealed system and you have to vent the aux tank into the trucks system. I would gravity feed any aux fuel tank gas or diesel.

Denny

chances are it would have a fit if was tied in..if you leave the fuel cap loose alot of newer trucks will throw a code..you would be better off looking for a larger aftermarket tank that meets spec so you won't have a bunch of emission codes thrown..