So, I've picked up a marine tank for the truck. It fits fine in the front of the bed with only two issues. The fuel inlet and outlet.

The inlet I can handle and the outlet I think will work, just need a second opinion or two. The outlet has a fuel pickup tube mounted on top of the tank extending to within about a 1/4" of the bottom.

If I tie the aux tank into the filler neck and block the factory tank vent, venting both tanks throught the aux tank will it siphon down into the factory tank as long as the oem fuel cap is tight?

I don't have the ability to weld aluminum or I'd put the outlet along the bottom of the tank and just gravtiy feed and forget the siphoning bit.

Thanks

RJR

 

I dont know if gravity feed is legal.. If it were me, Id install a fuel switch like a pollak (I have two 6-port ones for sale new in box =p) or hydraforce 3-port valves. Then you could switch from one to the other. Two 3-port switches would allow you to use the fuel return and feed to move fuel from one to the other also. This is how Ive got mine set up. I have two aux tanks under the bed so I use a pump to level them.
maybe you could just stick a holley blue under the bed somewhere and use that with a toggle switch or float switch to move fuel to the main tank?