Just finished installing my custom built auxiliary fuel tank in the bed of my truck. I didn't like the cost or the size's of most of the units I've seen. Wanted something that would fit under the rails and not take up too much bed space. A buddy of mine own a fab shop and makes some tanks for some Bio guys. What we came up with was a aluminum tank made form .100" sheet. Measures 48"W x 17"H x 12"L. capacity is a reasonable 41 gal. Got the rollover valve from Jegs, and picked up an aluminum vented filler neck and cap assembly from an aircraft supply house I found on-line. We installed two internal baffle plates to control fuel slosh. we also welded on an external tray and tabs to hold my 6 gal water / meth tank. I have a filter pump from a Cat, but haven't installed it yet. I'm currently just using a gravity feed kit from RDS. I was actually suprised on how quickly the gravity feed with a 5/16" line will fill the main tank. It filled a 1/4 tank in about 15min of driving. I'll have some pics of the build and install in a few days.

Love to see this... Sounds interesting...

:crickets:I know it's an 'old' thread, but still.. I've contemplated building a fuel cell to replace the spare tire area, being that I'm already short on cargo space with the 6.5ft bed...

Yeah he was last on back 11-21-10... I don't think you going to get a reply from the OP...

With the short bead it's tough to find a unit that isn't 18-24" deep. the unit I had built was 12" just for this reason. It's worked very well this past summer.

Spoke to soon... Hey ther Uber...

I have the opportunity to buy a Rear Fuel Tank from a '95 Ford F350. Anyone seen a good write up that details installation for use as a transfer tank into the main tank? I don't want to run the truck straight from this auxiliary tank in order to protect the VP44.

Well you could just use 2 valves one for the suction lines and the other for the return lines. Then both tanks would be usable. As for pumping from tank to another typically results in a mess. I seen so many times where a person does this and then ends up over filling the tank and pushing diesel out of the main tank all over the highway. Best to just hook up both and use the second tank first then flip back to the original tank as a second because it has a gauge. Or if you really slick change up the sender and hook both up on a toggle switch. My old 1972 Dodge had the behind the seat tank and then a aux tank under the bed. Just had a pull knob toggle switch that controlled the fuel valve and the fuel gauge. Same thing could be done on our truck just got to plumb the return line too.

Multiple tanks is common in marine applications... the problem is the valving for the return lines. Maybe someone knows of a dual valve, because 2 manual valves are not mistake proof. And no there's no guarentee that a T will split the return flow equally. In one 35' sport fishing boat, the uneven return had the boat tipped so people were in danger of falling out of their seats. As Mike stated, the risk of spilling expensive fuel & GETTING FINED FOR the spill, would certainly cool me from the project.

I am pretty sure you can buy the Trax-II fuel operating system from Transfer Flow. That is what was on my truck when I bought it and it works great. If I fill up the main tank, then the 98 Gal Aux tank it won’t start to transfer any fuel back to the main tank until I get to about 22 gal, then it will take it back to about 30 gal. It tells you how much you have in each tank. When the aux tank gets down to 35 gal it will balance the amount of fuel you have in both tanks, and tell you how much total fuel you have on board. The only thing weird about it is the stock fuel gauge now measures how much total fuel you have on board. So when I am down to 65 Gal total in both tanks it registers ½ tank.

So why not run a system similar to a semi truck?? They have a "T" return line, but they also have a small diameter hose that runs between to 2 tanks to help keep them at the same kind of level. Technically you really wouldn't even need to ever draw fuel from the other tank. Your stock gauge would still tell you your fuel level, but it would be more of an "overall" situation. Put a valve in the return and the balance line and you could effectively turn the second tank off as well.