So I found a tank to fit. Rear tank from a F150, but not sure how to rig it.

Option 1: Set it up as a true dual tank setup, being able to choose which tank to take from.

Option 2: Set it up basically as a permanent jerry can and have a pump that feeds into the regular tank.

Option 3: Gravity feed into the regular tank, maybe put a 1-way check valve in so it doesn't backflow into the aux tank.

 

Depends on how bad you want it. If you really wanted to, you could probably rig up some sort of a marine fuel tank in the bed(if you have a pickup). I was thinking(and just thinking, don't flame me for an "oakky" idea) you could maybe get one of those plastic marine fuel tanks from Cabela's and mount it in your bed for an extra 12-28 gallons of capacity. Those tanks are strong, UV resistant, and relatively compact, so you will still have room for other gear. You could probably hook it up to your main fuel tank using gravity feed from the bottom of the aux. tank. I recommended the marine ones because they are pretty cheap($80-$200) and you could mount it so that it could be easily removable. If you have a 4Runner, you will lose the use of your spare tire storage area(if it's under the rig). I think you could get some sort of a flatter marine tank for under there, it should be easy to mount with all the frame support under there. As for the fuel delivery, you may have to get some sort of fuel pump, and rig it up to your main gas tank. I think you could also just hook up a "T" connection to your main fuel line, and split it right in, mount a toggle switch for the aux. fuel tank pump, and presto, you've got fuel from both tanks. As for protecting the tank(if you mount a plastic on under the rig) you may want to seriously consider some sort of skid plates. some steel support beams could be bolted to brackets that are welded to the frame, and then a flat piece of 1/8th inch steel(maybe not even that thick) could go over the support beams. Now you have extra fuel capacity, and protection for the aux tank. Not so simple if you have a 4Runner, but it can be done. Please don't flame me for such an "oakie" idea.

 

I would do option 2.

That way, everything stock (fuel pump, fuel gage, etc) will still work as it was designed and you have a lot more mounting options than being restricted by gravity feed.

 

I have a rear mounted spare as it is, so that's not a worry. The F150 tank fits awesome up where the spare used to fit. I think i'm going to go with option 2. I made a little skid pan for the tank as well. now I just need to find a spot to put a filler neck.

 

What year & model F-150 did your tank come out of ? Was it a US or Canadian model ? And how many gallons is it ?

Thanks

 

It was a 91 F150 that had dual tanks. Probably a canadian model as I live in Canada. Haven't checked the capacity, looks to be around 17gals or so.

 

I run gravity feed now. Worked OK until I raised the main tank 3", now the height difference is very small and it is hard to get the siphon going, but it does work to some degree. Will be adding a low pressure transfer pump with a switch on the dash. That way can run the main 17 gallon tank near empty, then transfer the whole 13-14 gals. from the aux. tank to it. Adding the pump will also help w/ smog checks as well, since the aux. tank is not directly connected to the main tank and is now just a transfer tank (like a big jerry can). I have the NWMP tank and it includes a filler neck that runs under the frame and up into the back corner of the rear wheel well.

 

What are you doing for filler neck location?