I'm considering adding a 75-100 gallon tank in the bed of my truck. The more I think about it, the more I think that setting it up as two separate tanks with a selector valve is the way I should go. I also don't want the tank in the bed to gravity feed. I would like to size a lift pump and selector valve so I can switch between tanks. I also plan on putting a filter with water separator in line from the larger tank.

Will a standard 3/8 fuel tank selector valve be large enough for the fuel flow? Keep in mind the stock tank will also be going through this line.

How large of a lift pump should I get? The highest my obdII gauge has gotten for my fuel consumption that I have seen is around 13GPH. Will a 35 GPH lift pump be enough? The last thing I want to do is starve this thing of fuel!

 

best way to go about thisis to plump the aux tank in the the filler neck of the stock tank.
theres lots of dot laws to follow on this but the basic version is simple. you can not supply an injector or carbuator directly from a aux tank.
IMO the bigist reason is by doing that you by pass the fuel cut of swich.

 

Granted I don't know how "legal" this would be...but the guys running WVO use a separate fuel supply system that by-passes pretty much everything but the injectors.

http://www.biofuelstechnologies.com/...mart&Itemid=54

Vegiestroke is a forum sponsor in the Alt. Fuel sub-category. I know he used to offer a kit for the 6.0L; but I've yet to talk to anyone that's running the system. I agree with cheezit; by-passing the fuel cut-off circuit is a bad idea.