Here is the auxiliary gas tank installed where the spare tire would normally be. The tank was alot easier to install on the Superduty because there is so much more room. My truck didn't come with a spare tire so I don't have anything to remove. The tank was very noticeable on the GMC, but is almost hidden on the Superduty. Below is a picture of the tank fill in the wheelwell.
This is another place where the tank fit better in the Superduty than the GMC. The filler pipe rests nicely on the overload spring snubber bracket.
The normal way to plumb an auxiliary tank is to have a fuel pump in the tank. When the main tank is empty you throw a switch and the gas is pumped from the auxiliary tank, through a switching valve, and to the motor. I had it this way on the GMC, but it ate two $90 fuel pumps and one $65 switch valve. I called Aero Tanks after the first pump died. They said to change the fuel filter every 5000 miles to insure there would be no blockage for the pump. I did this, and a year later another fuel pump quit. I was tired of replacing fuel pumps, so I changed to a simpler way of plumbing the tank. I used a Holley electric fuel pump to pump the fuel from the auxiliary tank to the main tank. The tank fill hose for the main tank has a 3/4" vent hose. I 'T'd' the supply line from the auxiliary tank into this vent hose. When the main tank is empty I turn on the Holley pump and the auxiliary tank fills the main tank. Simple, and works like a charm. When I put the auxiliary tank on the Superduty I used the same plumbing method.
The only problem I have is filling the auxiliary tank. There is a 90 degree bend in the fill pipe before it goes into the tank. I think this causes a restriction. You have to fill the tank on the slowest setting and have the nozzle positioned 'just right', otherwise it will kick off. I'm going to see if I can find a better solution for the fill hose so it fills faster. It takes a long time to fill 30 gallons on the slow setting!
Update Summer 2002: - I refurbed the tank and solved several problems.
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