dual tank idea

[jreb333]

i found a nice aux tank with the filler neck cover in the bed still intact and everything.
heres my problem: the truck i have now is not equipped with dual tanks and tho the extra capactiy is nice i dont like the whole switch thing and im not going to cut a hole in the side of my bed.

would it be possiable / advisable / safe to put a 1 1/2" line going thru the rear of the cab gravity feeding into the aux underbed tank? could i just use the fuel gauge sensor and fuel line hook-ups on the lower tank and cap the ones on the behind the seat tank off?

any ideas/advice?

thanks

[heep70]

Anything can be made possible. Sounds like you have a interesting idea.

Are you going to get rid of the behind the seat tank? It might be hard to find and expensive to run the proper gas filler hose to each tank. You would also have to have a "Y" in the hose so that both tanks get fuel.

Make sure you can get the two tanks out of the other rig before taking yours apart. The bolts that run up through the tanks are know to rust up and break the tank apart when trying to take them out.

[FORDification]

...Make sure you can get the two tanks out of the other rig before taking yours apart. The bolts that run up through the tanks are know to rust up and break the tank apart when trying to take them out.

It depends on what style of tank he's found. If it's the factory add-on tank that hangs from the bottom of the bed and has a small aluminum door on the bed side for the filler tube, they bolt on with straps. Or if he's found the factory in-frame tank, it's also attached with straps. And the dealer add-on tanks that I've seen have no provision for a sending unit, so that would have to be fabricated.

OK, here's my thoughts FWIW: I just don't think this whole idea sounds very safe, to be honest with you....though I can't say why. But to make it work, both tanks would have to be removed, cleaned out and then have welding done to them to add filler necks to which the hoses would connect.

I think it would be a WHOLE lot easier and safer to just add a small hinged access door in the bed to access the auxiliary tank, if you're not set on cutting a hole on the outside of the bed.

[magnethead]

I say do it in a master/slave system. have the under-seat tank "feed" the new tank, putting the fuel feed and such on the new tank, and caping the same ones off on the old one. That way when you fill the current one, it feeds the new one via the old one, and when the new one fills up, it just starts filling the old one.



Make sense?

[FORDification]

That wouldn't work as you describe, if I'm understanding it correctly.

1) The auxiliary tank sets lower than the in-cab tank, so the fuel won't run 'up-hill'.

2) He would still have the issue of where to put the auxliary tank's filler neck.

I still think you should consider the access panel in the bed. Or you could redo the filler neck so that you'd fill the auxiliary tank through the wheelwell, like some of the dealer add-on tanks.



Of course, it would require a little fabrication on the filler neck to stretch from the wheelwell over to the tank, but at least your box will remain untouched.

[willowbilly3]

I have those dual aluminum door tanks and I know the ones on the 72 have bolts going right through them into the bed. Well anyway I think you could cut a hole inside the bed and add a hose and filler neck instead of the ugly door thing. None of those have a guage but I don't find it a problem. I just use the original tank last when on the road. The ones on the crewcab are only 9 gallons each as it is a shortbed. So I know I have about 90 miles if I am towing the trailer. (haven't done a road trip empty) My long range plans for a gas tank are the 36 gallon Suburban tank to go between the rear frame rails, as soon as I get off my duff and get a Ford sending unit in it.. I haven't decided where to fill it yet but I am considering doing the filler behind the tail light ala 57 Chevy.

[jreb333]

That wouldn't work as you describe, if I'm understanding it correctly.

1) The auxiliary tank sets lower than the in-cab tank, so the fuel won't run 'up-hill'.

2) He would still have the issue of where to put the auxliary tank's filler neck.

ok clarification on my idea:
the idea is to weld in an outlet pipe on the bottom of the in-cab tank that leads to the under-bed tank. then connect the existing fuel gauge sending unit wiring to the unit in the under-bed tank. then run the fuel lines to the carb from the under-bed tank. this would cause the in-cab tank to gravity feed into the under-bed tank (which has its fillerneck cut off and sealed) thru the stock in-cab tank fillerneck basically making it all into one big fuel tank.

[magnethead]

thats what I said (but i didnt explain it as well)

[willowbilly3]

I actually saw a picture where someone had done just that. No reason it wouldn't work if you do it right. I would have a muffler shop bend the pipe so the metal exits the cab, then put the connector hose in. Just in case you are ever in a collision and the cab shifts you don't have the seperation point inside the cab with you.

[FORDification]

OK, I've been giving this some thought, and I'm still not convinced it'll work, mainly due to the installed height of the in-cab tank.

I'm thinking that the weight of the fuel in the upper in-cab tank will cause the fuel to FORCE itself down into the lower auxiliary tank, essentially pressurizing the lower tank, where it will continue up through the pickup line to the fuel pump and rupture (or at least play havoc with) the fuel pump diaphram. The fuel isn't supposed to be under pressure until after the fuel pump.

I thinking this is why all fuel tank pickups are attached to the top of a tank instead of the bottom.

I'm not saying it WOULDN'T work....but I'd have my doubts on whether it would be worth the hassle for purely cosmetic purposes, especially when there are much easier alternatives.



You could go ahead and try it though...and let us know what you find out. You can be the guinea pig. Keep good notes....and have lots of floor-dry (and a fire extinguisher) nearby.

[willowbilly3]

Keith, I think he was talking about 86ing the in cab tank all together and just using the original filler lpcation to fill the chassis mounted tank.

[FORDification]

No, he was stating he wanted to join the two and essentially make one large tank:

ok clarification on my idea:
the idea is to weld in an outlet pipe on the bottom of the in-cab tank that leads to the under-bed tank. then connect the existing fuel gauge sending unit wiring to the unit in the under-bed tank. then run the fuel lines to the carb from the under-bed tank. this would cause the in-cab tank to gravity feed into the under-bed tank (which has its fillerneck cut off and sealed) thru the stock in-cab tank fillerneck basically making it all into one big fuel tank.

[jreb333]

yes i want to keep both tanks. the pressure idea is definately a valid one. that much volume would probably create too much pressure for the pump to handle. how about an in-line pressure regulator?

[willowbilly3]

Right you are my friend, I must have just woke up or something.

You can make anything work with enough tenacity but I think there is a better way to solve your problem, what ever it might be.

[magnethead]

i think the regulator idea would work.