Aux Fuel Tank, Saddle Tank Hook-up

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I'm getting behind here guys, so any help will be greatly appricated. I've welded up a 15 gal. tank that goes outside the frame, in front of the passanger side duels. It's 34" long, 12" wide and 12" high. Bottom is 3/16" steel plate, everything else is 1/8 plate. Mig welded inside and out (except of course the top, not that good). It fits around the bed supports and the front spring hanger.

Plan is to transfer fuel with a 12V pump from the aux tank into the main tank by teeing into the vent line connected to the main tank filler tube. '

Now the question, why can't I install a "Y" fitting in the main filler tube connecting it to the top of the aux tank, and not vent the aux tank. My simple logic says that the main tank will fill, then as the fuel level reaches the "Y" connector, it'll flow into the new tank. Since the new tank's filler tube line will be 1 1/2"ID, I'd think there would be sufficiant internal volume to allow air to excape from the aux tank without impeding the incoming fuel flow. Also, since when transfering fuel from the aux tank the inlet hose will be empty, or quickly that way, will it act a vent for the small tank, allowing it to use the factory tanks vent, making an additional vent unnecessary in the aux tank?

Hope this makes sense, thanks.

Ronnie


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"95" 3500, 4WHD, Ext cab. SLT, 5 spd, 4. 10 LSD, Rancho 9000's PacBrake, running boards, Mopar mud flaps, Isspro EGT, 50lb. boost, TST #8, 215HP injectors,no cat, muff or turbo ring.

 

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It sounds good on paper but I'll bet you $2 it won't work. My first guess is that the foaming will screw things up, cutting off the pump every two seconds.

When I installed my aux tank, I made a double T out of brass fittings and put it into the vent line as you suggested. The lower T is connected to the fuel transfer pump. The upper T is connected to the vent of the Aux tank.

If the Aux tank overflows like it will when you park a just filled tank in the sun, the fuel flows into the main tank. Also, when your transfering fuel, the tanks will always be at the same pressure.

An additional benefit, should anyone care, is that it should meat EPAs venting rules whatever they might be.

Hope this helps, John.

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John S. '99 QC 1T 4. 11 A/T Leather Driftwood, 50 Gal aux tank/tool box, gearvendors, BD brake/autolok, BD ISB comp, guages, BD Pressure Lock and Pract. Sol. Boost Elbow.

Just a Little BOMBed and liking it a lot.

 

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Ronnie,it seems like there isn't much room for a tee between the fill neck and the tank and if there is your main tank would be close to overflowing before the aux starts filling. Even if it has to fill slow it's easier than putting in another fill neck for the aux tank though. If you were to use a bulkhead fitting installed low on your main tank connected low on the aux tank,you won't need a pump. The aux tank will need a vent,but both tanks will fill/empty at the same rate if the hose between them is large enough. Just throwing out some ideas,like to see where this goes.

 

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my aux tank has a bottom fitting and two top fittings.

I inserted a 3/8 inch brass fitting into the main fuel filler and the vent line.

I then plumbed the bottom tank fitting into a cutoff valve into a fuel pump into the main fuel filler neck.

I ran a fuel line from the aux neck up to a T, one ran to the aux tank anti siphon valve (for main tank venting) the other fitting into a straight fitting on second opening on top for the vent for the aux tank. DOT legal EPA approved very reliable and fast movement of fuel depending on GPH movement of the fuel pump. 3300 mile range. If only OJ had this setup we would still be watching the chase. #ad