I'm thinking about adding an aux tank to my single cab short bed, since I don't have a spare under it. I'm just curious as to how people would solve the filling/transfer problem? It doesn't seem like it would be too complex, either add a spill over from the side tank into the rear for filling, or even add a second filler in the bed, and then just a switched electric fuel pump to transfer it up to the front tank. What would you do?

 

I'm thinking of going with a 32 gallon Bronco tank in the rear of Big Blue and not have the side tank and the switching valve. But, being a long-bed with two filler doors that's easy. Not sure what'd I'd do on a short-bed. Maybe run marine gas hose from the filler to the rear tank?

 

I thought about running another line up to the filler neck, but I'm not sure there's enough room. I like the spill over idea, I think it would be pretty simple and fail proof

 

There is an option of adding a tank in the bed of the truck too (mounts in the front of bed like a tool box).

 

You are going to put a tee in the original filler pipe and put another filler pipe to the other tank? I am thinking that is not going to work.

When you are filling the tank at the station, you are "shooting" the fuel down the pipe, so fast that they have another hose just to let the air out without mixing with the fuel and making it spit back and cut the nozzle off. To fill the other tank with a y or tee in the line would require you to put the fuel in very slowly, you would be at the station a long time.

I would try to figure how much trouble it would be to fill a bronco style tank at the back. The filler location will be a problem, and the spare tire location will be a problem. If you did that though, you could get rid of your side tank and that would free up room for exhaust pipe options.

 

The cleanest way to add a second tank is to do it like Ford did. Even with a spare under the bed there's room for a factory rear tank between the frame rails behind the rear axle. You can add an aftermarket filler in the bed side behind the rear tire, or with some bodywork (or a new bed) use real Ford parts for a factory look.

You can also go with all factory parts for the switching valve and fuel lines, but there are aftermarket available too. Or you could use a pump to move gas from the aux tank to the original. Personally I wouldn't choose to do it that way. If the aux tank were close in size to the main (or bigger) you'd have to be careful to not overfill the main tank. And electric fuel pumps don't like to be run dry, so you'd need to be careful to shut it of before (or right after) the aux tan was empty.

And yes, a lot of people do like going to the simplicity of a larger single tank. Personally I kind of like dual tanks though. With a single tank it's hard to know how much you can "push" it. With duals you can run out of gas "pushing" a tank too far once or twice and get a good idea of where that is, so you can make the most use of the gas you have with more confidence. And I haven't found a better place to carry a spare (in my opinion) and I don't like the idea of not having a spare, so the 32 gallon Bronco tank isn't an option fr me. But simplicity is good too!

 

I am doing a custom install using all Ford factory parts.

The custom part is my short bed is a flare side and they never came with duel tanks.
I will be grafting on the second filler door from my style side parts truck the duel tank parts came from.
https://www.ford-trucks.com/forums/1...ide-build.html
If I find between the stock 16 gal side tank and the 19 gal rear tank is not enough I will replace the rear tank for a larger Bronco tank but than I have to figure what to do with the spare tire. Right now it fits under the stock 19 gal rear tank.
Dave ----

 

this isn't really what I was thinking of Franklin, I was thinking more along the lines of a hose running from the top of the main tank to the top of the aux tank, so that when the main is full it spills over into the aux.

I definitely won't be grafting anything onto the bed sides of the truck, since the body work is already done. In the bed would be an option, but still not the best option for me I don't think. Regarding the spare, I've yet to really attempt it but running a 35'' I don't think theres enough room between the rails to fit that anyways.

 

If you add a rear tank and don't want to cut a new fuel door into the side of the truck, you could add a trap door in the bed of truck.
The downside is you cant open the door if the bed is carrying something big - but the upside is that you don't need a body/paint shop to blend a filler door into the side of the truck.
bed mounted fuel door - Bing images

 

Either get another bed or if yours is good rust free find a rusty bed (junkyard) and cut out the section with the rear filler. Take the metal filler pipe and rubber fill hose as well as a rollover valve and grommet from either front or rear tank of the truck you use for parts. Also get the rear fuel tank straps (top and bottom, though new bottom straps are available for about $20). When cutting out the filler panel I would cut to the bottom of bed and start of wheel arch to help you locate the filler panel properly on your bed before you cut it. You can get these parts from any truck 80-97 with a rear tank, i believe they are the same. The sender/pickup will be specific to EFI/carb/diesel and somewhere along the years the resistance range changed. You'll want the fuel tank selector valve and switch as well.

Then get either a new 19 gallon tank or a new 38 gallon tank (F26-C for small/early sending unit, F-26E for larger in-tank EFI pump and diesel sending units). Bolt the tank in and call it a day. The 38 gal requires extending the pickup tube, you can use copper pipe and a compression fitting coupler/union.

I recommend doing the external vent mod, which is eliminating the in filler vent and adding an external 5/8" vent hose (fuel rated). Get a plastic 90* fitting with a 5/8" hose barb and gut/drill the rollover valve epoxying the fitting in. I used a hot drill bit of appropriate size, working by hand. Trying to drill normally just cracked the fitting. Use a NPT fitting into the side of the filler neck near the top, and add a small line (1/8" maybe) into the rubber hose for a vent.

I think that's about the bulk of it, but bottom line is I wouldn't hack it together with anything other than perfectly fitting parts made for the application unless 38 gal+16gal is already done and is insufficient fuel capacity.

Also I suspect any sort of gravity feed or crossover for a secondary tank is not DOT legal for gasoline. More work than it's worth to do it safely when easy factory options are available.

 

Franklin's concern is still valid. Unless you run about a 2" hose from the top of the main tank to the top of the aux you will be backing fuel up the filler neck and will never fill the aux tank. Even with a 2" hose I bet the gas pump would shut off constantly once the main was full.

If you want a simple "dumb" system (not saying it's a dumb idea, I'm saying that it doesn't need any "smarts" to operate it), you could put a transfer hose between tanks at the bottoms of the tanks. That way you'd effectively have a single, larger tank. But adding a fitting at the bottom of a tank is asking for leaks. And when on steep hills you might have a transfer problem.

The tire doesn't go between the frame rails, it's below them (the tank is between the rails, which is why you can have a rear tank and an under-bed spare). I'm not 100% sure there's room for a 35" tire, but I know there's more than enough room for a 33".

Not the same over all those years. There are a few differences in the beds (if doing an entire bed swap), with I think the '80 - '86 being one style and the '87 - '96/97 being another. And even if only grafting in the fuel filler door, that's one of the differences, with the earlier trucks having a "dent" in on the bedside so you can get a finger behind the flat door to pull it open, and the newer ones having flat bedsides, but a bulge out on the door to get a finger into.