[Montana Man]

Originally Posted by bshgto

You modified the fuel system with a non factory supplied and approved product. The fuel system is regulated by the Feds ( EPA I think ) you change ANYTHING in that system you`ve changed what the EPA has approved. The dealer will walk away from your truck.
Case in point ...I had a brand new 2006 350 Ford diesel. I put an aftermarket auto start system on the truck. Soon after the truck fuel gage would not go below a 1/4 tank. Took it to the dealer for repair when they realized that I had put an aftermarket auto start on the truck that was effecting the fuel gage they came out with this official Ford document that basically stated and any electronic modification or other wise that effects the fuel system voids the trucks warranty, period no exceptions. I just let it go and put up with it till I sold the truck.
You have modified the fuel system by adding another fuel pump to the factory tank which could over pressurized the system and leak (just like mine did). Even with a gravity feed the head pressure of 45 to 80 gallons of fuel will cause you fuel cap to leak (mine did) if you forget to turn it off and over fill your main tank. It`s a safety issue for them full of liability problems. If you cut into the filler neck for your new fuel tank you have modified the FED approved fuel system. This issue came up on another forum board that the dealer voided the guys warranty for adding another tank in his bed and modifying the fuel system he had a GMC truck. I`ll see if I can find it and post it. It`s just like you can`t modify in any way the seat belt system in your car/truck. Some dealers may skip this but mine would not.
The sellers of these tanks aren`t going to tell you this. They have approved tanks for sale but also say built and used for no specific purpose. I put my new tank in my truck knowing this. I suppose you know that you have to securely bolt your new tank down and have a FED required roll over valve on the tank and no other modifications to the tank that would void the warranty or the FED/STATE approved tank. YMMV
This would be your tax money at work for you/protection....don`t get me started on that.

I can't speak to current law but it used to be a modification in one part of the truck can't void a warranty for the whole truck. Only the system affected. Nowadays, the fuel system is part of the emissions system and is warranted for 100k miles in some cases. It may be splitting hairs to tap into a filler hose but may be enough reason for a dealer to deny repairs on smog systems.