Aux fuel tank

That is the million dollar question and honestly why I was thinking of using the sending unit as a transfer pump initially. Too many unknowns.

Probably more like $200 question... but yea. :p Anyone know how simple it is to wire a pump to a simple switch that can be toggled in the cab?
 
I would not have the tanks linked together. If you poke a hole in a tank, then both tanks will empty out.


It is really simple, plumb the Camry fuel pump to the 4runner fuel system and wire up a switching valve to change the return to the appropriate tank.
 
I would not have the tanks linked together. If you poke a hole in a tank, then both tanks will empty out.


It is really simple, plumb the Camry fuel pump to the 4runner fuel system and wire up a switching valve to change the return to the appropriate tank.

It's the ability to fill the tank that I'm more concerned about. Oregon has more ass-backwards rules about what tanks can and cannot be filled and to what amount. We don't even get to pump our own gas - and I'd prefer not to have to fill up 4 5-gallon cans so I can fill the tank on the down-low at home. So it either needs to fill off the primary tank, or tie into the existing filler neck with a valve.

A tank selecting valve should be easy to source since most older domestic pickups had saddle tanks with selector switches. So that sounds very do-able, although I'll have to upgrade the Camry fuel pump to put up with my S/C's needs.

On a plus note the tank fits nicely between the rails.
 
We have a term for what you guys are doing with this Aux tank thing in the Navy.

It's called "nuking" it.

You're OVER THINKING the PISS out of this set up.

Here is a cruel drawing for ya.....

It's not that hard.

Run the filler to the Camry tank from the STOCK location.

Run a line from the CAMRY tank to the STOCK tank.


Wham, Bam, Thank You Ma'am.

There is no reason to think about the evap system, because you're not modifying the tank. You're ADDING another tank, thus increasing the CAPACITY of the VEHICLE. Not the TANK by itself.


The Camry tank is just a reservoir. Nothing but 5 Jerry cans strapped to the under side of the truck.


The TRICK, is to make sure you get the transfer line at a low enough point on the AUX tank where it will get ALL the gas out of the tank.

You need a 1* drop from the damn transfer tank to the Stock tank. That's enough to keep the fluid flowing south.

The gas Guage will read full, until you use the gas in the AUX tank, and then will start getting lower because you're using the fuel in the STOCK tank.


I can see how that would be a problem for some of you, but shit, you already know the damn mileage your 4Runner gets PER TANK.

Make sense now?
 

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We have a term for what you guys are doing with this Aux tank thing in the Navy.

It's called "nuking" it.

You're OVER THINKING the PISS out of this set up.

Here is a cruel drawing for ya.....

It's not that hard.

Run the filler to the Camry tank from the STOCK location.

Run a line from the CAMRY tank to the STOCK tank.


Wham, Bam, Thank You Ma'am.

There is no reason to think about the evap system, because you're not modifying the tank. You're ADDING another tank, thus increasing the CAPACITY of the VEHICLE. Not the TANK by itself.


The Camry tank is just a reservoir. Nothing but 5 Jerry cans strapped to the under side of the truck.


The TRICK, is to make sure you get the transfer line at a low enough point on the AUX tank where it will get ALL the gas out of the tank.

You need a 1* drop from the damn transfer tank to the Stock tank. That's enough to keep the fluid flowing south.

The gas Guage will read full, until you use the gas in the AUX tank, and then will start getting lower because you're using the fuel in the STOCK tank.


I can see how that would be a problem for some of you, but shit, you already know the damn mileage your 4Runner gets PER TANK.

Make sense now?

Of course I'm over-thinking it. That is the fun of a forum. I get 9 hours a day in front of a PC, whereas I'm lucky to get an hour a night under my truck. I like the simplicity of the plan, I'm just not sure how your set-up allows gas into the Camry tank without causing a standard gas pump to auto-stop. It would require the stock tank and filler neck to fill which usually stops all modern pumps. The only answer I see it to either valve it or daisy chain it.
 

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Sorry to bust your bubble but can have the secondary tank any higher then the the stock tank. If the fuel level is above the stock tank, it will flood the Evap box killing it and drawing gasoline directly into the manifold.
 
Sorry to bust your bubble but can have the secondary tank any higher then the the stock tank. If the fuel level is above the stock tank, it will flood the Evap box killing it and drawing gasoline directly into the manifold.

sing toe is 100% correct. the camry tank is going to have to run independently along side the 4runner tank, like the early efi F-Series trucks that had dual tanks. flip a switch flip your source.
 
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Of course I'm over-thinking it. That is the fun of a forum. I get 9 hours a day in front of a PC, whereas I'm lucky to get an hour a night under my truck. I like the simplicity of the plan, I'm just not sure how your set-up allows gas into the Camry tank without causing a standard gas pump to auto-stop. It would require the stock tank and filler neck to fill which usually stops all modern pumps. The only answer I see it to either valve it or daisy chain it.

YOUR DRAWING!

You DON'T fill both tanks. You fill the CAMRY tank, thus filling the 4Runner tank.

Sorry to bust your bubble but can have the secondary tank any higher then the the stock tank. If the fuel level is above the stock tank, it will flood the Evap box killing it and drawing gasoline directly into the manifold.

I don't understand. It's just topping off the stock tank. It's not doing anything else?
 
Just looked at this thread and read the last few posts, so sorry if I'm reiterating...

Why not just have the two tanks level with a connecting hose, so they are both at equilibrium, then you just have to fill the main tank and it will fill the secondary tank. The gas gauge is still valid then since it just measures height of the tank, which will just decrease slower since gas will be getting sucked from both tanks at the same time (since they maintain equilibrium).

Obviously you can't switch between tanks, and if one gets punctured you're screwed, but as long as your skid plate is decent on both tanks you would be fine.
 
The problem I see with that is having them at the same height:

the rear axle assembly is right there. Coils, links, ect ect are in the way of getting ANY kind of decent fuel tank in there.

I could be wrong though. I've been wrong before...
 
In my test fit it was significantly higher than the stock tank. Lowest point on the Aux is about the middle of the stock.

I want to trace out my evap system to see what works.
 
Just looked at this thread and read the last few posts, so sorry if I'm reiterating...

Why not just have the two tanks level with a connecting hose, so they are both at equilibrium, then you just have to fill the main tank and it will fill the secondary tank. The gas gauge is still valid then since it just measures height of the tank, which will just decrease slower since gas will be getting sucked from both tanks at the same time (since they maintain equilibrium).

Obviously you can't switch between tanks, and if one gets punctured you're screwed, but as long as your skid plate is decent on both tanks you would be fine.

There isn't any issue if they are at the same level... the trick is we are stuck on having a high and tight Camry tank above the frame rails under the bed. If it were dropped to a lower position below that it could work, but would me you lose clearance. We're all just jaw jacking and saying what theoretically works and what doesn't and why. The fact is I don't think anyone knows exactly what will happen in each given scenario so it makes for lots of opinions. Valid or not, it's good to bring up.
 
i'm very interested in this idea :popcorn:

Geohil: any info on the camry tank? what year? is it v6 or 4 cyl? is the v6 tank larger? overall dimensions, pics of it mounted etc. thanks!
 
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i'm very interested in this idea :popcorn:

Geohil: any info on the camry tank? what year? is it v6 or 4 cyl? is the v6 tank larger? overall dimensions, pics of it mounted etc. thanks!

It is out of a 1996 4 banger. I've been crazy busy so it hasn't been mounted. I have determined I'm going to use the OEM sending unit as a transfer pump though. Gives me a little bit more flexibility mounting wise then with a gravity feed.
 
Yea i'm liking that idea more and more too. when you get a chance, can you grab the overall dimensions of the tank for me?
 

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