Dual Gas tanks
 

I'm buying a 56 100 with a 72 250 frame, motor, tranny, and tank. Right now the gas tank that is hooked up is the 1972 tank and as far as I know the 56 tank is where it should be just non functional.

I mean to have them both working. How hard will it be to make dual gas tanks work and how am I going to do it? I know exactly... nothing. :-X07 so don't feel like your hurting my feelings if you explain it like you would to a 2 year old...

David, it would depend on how you wanted to use the extra tank. First of all, make sure the oem tank is clean and leak proof. Second, if you want to use gas from each tank seperately, you would have to install a tank selector valve( feed from each tank to the valve and one line out to the fuel pump). This could be a manual valve or an electric valve with a selector switch. The last decision is how do you want your guage(s) to work. If you have a guage for each tank, just match the guage with the sending unit. If you want to have a common guage, get the parts to match your donor tank along with the selector valve, and rocker switch. You may have to modify your oem tank to accept the donor sending unit. Is that clear as mud? One other option is to allow both tanks to supply fuel at the same time by just a "T" fitting to connect in the oem tank. Hope this helps.

Gil

Whatever minor benefits you may find with the stock gas tank are far outweighed by benefits of removing it...namely the risk of gasoline fumes in the cab and the added space you get behind the seat. Save yourself some time and money, dump the stocker.

Well. My thought is that I want the truck to look as Stock from the outside as possible including the position of the gas tank. having it there and not working would drive me :-X09 so I need to get it working right for the sake of the people that have to be around me.

I know that I can get more space etc. by removing it but for some reason that gas tank cap sticking out where it is is part of the reason that I love these old trucks so much. I'm going to give it a thorough once over to make sure there are no leaks etc. but I think I'm going to keep it.

I want to use only one gas gauge and stick a switch somewhere so I can choose which tank to use and have it read the one that I choose. I have a 95 150 with two tanks and I love the feature.

Your logic is just a bit flawed, removal of the tank does not necessarily mean that you must remove the filler neck/cap as well. If asthetics are that important to you then go ahead and leave the filler in place. On the other hand, if multiple gas tanks are your thing then why not add a slant cab tank as well and have the stock 56 tank feed into it? That would still leave you with the problem of switching feeds and float signals. I would find a 12 vdc electromechanical valve that switch the fuel sources, that way you could control both the fuel and the gauge sources through a relay using one electrical switch and have the flexibility of mounting that switch anywhere in the cab.

I do like multiple gas tanks. Having the filler neck/cap there feeding into nothing would drive me crazy.

Can you explain how the slant cab tank works and how it would be connected? What does it even look like? Does is go down with the frame? I don't mind dumping the tank in the cab as long as I can keep the filler and its functionality.

This isn’t going to work easy, a tee will not work, there is this little thing about fluids and gravity, they run to the lowest point. The behind the seat tank is higher then the frame tank and will try to fill the lower tank with a tee until it overflows and the seat tank is empty. Some electric tank switches are spring loaded one way only and with the power off switch themselves to the other position (usually wrong). A brass valve tee might shut off the other tank but it is hard to tell which tank is turned on, two shut offs might work, should be fun at midnight on the freeway. :-X24

I did this in a car back when. Using a T connection, I put a one way, ball check valve in the output line of the lower tank so the upper tank fed first then the lower tank. I used the sending unit only in the lower tank, so the guage read full until the lower tank started to feed the engine. In your install it would probally be easier to use the sending unit in the lower tank anyway, since it's newer and 12vdc. chuck

I had a 66 Chevy C10 back in the 70s. It had the seat/cab tank. Gasoline fumes all the time.

It also had a manual valve mounted just inside the door sill on the driver side to switch to either of the two saddle tanks (mounted outside the frame in front of the rear wheels but behind the cab) or the seat tank. I always filled all three tanks, used the left saddle first (just as a practice), then the right saddle, and finally the seat (oem) tank. The seat tank was the only one with a guage attached. The saddle tanks had no senders, just fuel pickups.

It worked well, but I always knew it would be curtains for me if I was ever hit on either side! I often wanted that seat tank gone! I would not go out of my way to have one in a truck. I own a 1994 F-150 with twin tanks. I'd sure look into doing something like that on your vintage pickup, and loose the seat tank.

The early broncos had dual tanks and would be a good donor vehicle for parts. A manual lever under the driver seat to switch the fuel line and a switch on the dash to switch to the different sender.

Now I know why there isn't a lot of posting on Dual Fuel Tanks. WOW!

• If you are smelling fumes inside the cab all the time its because you may be mechanically challenged how to simple replace some rubber fuel lines, Vents, and some radiator hose pieces to join the filler necks. Its not that hard! I have had many behind the seat tanks, under seat tanks, saddle tanks, etc.... And Never have had any issues!

• To dispel even more SCARWEY Myths. Saddle, Behind the seat, Under Seat Tanks are no more dangerous than any other gas tank or position PERIOD! Stop with the lies and hearsay BS you all hear from the internet! Its very tiresome. Try not to be Sheeple People! Remember the Ford Pinto? HMMM I wonder where the gas tank was in that Car???? "Could It Be Satan? The safest place for any gas tank is under the cab, or in it! As most tanks are designed with the filler necks shielded and vented to outside. Most accidents are rear enders, or front enders depending on which way you look at it or get it... The Cab is the safest place to be as its the very last to get damaged or hit to the point of tank damage. I can attest to this as I have rolled my 55 Ford Truck end over end, side to side, engine ripped off mounts and thrown across four lanes of traffic, bed ripped off, doors ripped off, cab flatten and crushed down past steering wheel, hood gone, entire front axle, glass gone.... very serious accident, The only things that were not damaged were the tanks.... The very ones I am still using today 30 years later. I would rather have saddle tanks first, behind the seat tank next, and under the seat tanks lastly.... These trucks are designed for these in this position and have way more than enough protection and safety in place originally. So Again, Please vet your info.:-X15

• If you want to do Saddle Tanks Here is what you need. An extra set of Running Board tank supports from Drivers Side, The electric fuel valve switch from a 1986 Ford Van E350, create and weld up the original fuel neck into a Y with some additional 2: exhaust Pipe, Short enough to place the gas station filler nozzle into the top and bottom of the Y filler neck, This way you can fill both tanks on the original side, (drivers) with gas. You can simple go to wrecking yard and pull the electric switch (Dash) and valve (Under Van near tanks) from an 86 E350 Ford Van, The dash switch assy includes wiring for two sending units from the tanks to the switch, then from switch to the one single gauge in the dash. When you fit the hoses, wiring, etc... its a simple as a flip of a switch to switch between the tanks and the sending units. Displaying on the gauge.

I was looking myself for some other unique ideas from others but haven't come across any yet better than this... So I will continue to search and finish with my original idea unless someone's better ideas?

Wow a lot of off track info here, the answer isn't anywhere near as complicated as people are making it. All you need is a fuel selector valve from a 80s carbureted truck or diesel up to 93 and copy the wiring. The valve is switched with a simple switch circuit and switches the sending unit internally when the tank is switched so you can use one gauge.

There is more on the valve then you'll need but you can just not use it. They have 6 ports but you only need 3(3 are for return lines) and they have an internal switch to switch between in tank electric pumps which you don't have. Your mechanical pump will draw through it.

So you end up with exactly what you said you wanted, one toggle switch, one gauge, two tanks. Only hard part is ensuring the accuracy of the sending units but they should be rather standard.

I never thought of saddle tanks and factory-style under-the-running-board (behind the large frame rail) as the same thing. Ever.
Welcome to the forum. Please be gentle on those of us who eschew the vulnerable and exposed saddle tanks for the use of highly volatile gasoline. Where's the love?