dual fuel tanks on a super duty

[chief960]

want to put a second fuel tank on my 2000 f250 super duty i was thinking about a fuel tank in the rear between the frame rails from a cab and chasis truck was wondering if anyone has done this and if so can you plumb it like a mid 90's ford with a switch in the cab to switch tanks if so what would you need to do this and how complicated would it be

[JSchuricht]

The excursion tank is the popular one to mount in the rear. C&C have a different frame width but I have not seen any tank measurements. The most difficult part is going to be setting up the filler so it looks good. There is also a cross member in the rear that will need to be relocated along with the spare. I run two tanks with a switch. What you will need is a 6 port valve or two 3 port valves. Pollak is a low cost valve that is commonly used, Greasecar makes a much nicer one that can be taken apart if you neglect to install a screen and a piece of plastic from a fuel can finds it's way into the valve.

You will need to splice into the supply and return lines 3/8 and 5/16 IIRC and also splice into the sender wire. With the Pollak valve you will have to supply two wires that reverse polarity to flip the valve, the sender wire can be spliced into the valve and it will switch the fuel gauge source when the valve is flipped. A Greasecar valve is spring return so you only supply 12v when you switch to the aux tank and you will need to use a two pole switch so one pole switches the sender.

Some things you will notice... The fuel gauge takes about 20 minutes to move from empty to full when switching tanks. Your low fuel light will go out when you switch tanks but your miles to empty will not reset till you shut off the truck.

If you have a Air Dog, you will need one additional 3 port valve. You can also get fancy if you have separate valves and transfer fuel from one tank to another.