[Bulldawg44]

Hi All, I am looking for details, knowledge or basic been-there…done-that on adding an auxiliary fuel tank to my EB. I recently picked up a 75 Bronco with an EFI 351. It has a 23-gallon main tank with an electric fuel pump. The previous owner removed the auxiliary fuel tank, and I have been contemplating adding it back as a reserve tank.

My main questions are how best to set up the auxiliary tank.

Do I need to put an electric pump in it, and if so…how do I connect it to the fuel lines for the motor?

Do I put in a replacement stock sending unit, and send it over to the main tank?

Does anyone have schematics or drawings of how the stock systems were setup by Ford?

My EB has the toggle switch below the steering column that switches the meter reading. However, I cannot find a manual switching valve to change fuel flow. Where should I look for it, and do I need to install one if it has truly been removed?

Any advice / help would much appreciated.

[S_bolt19]

The manual tank selector valve is under the driver seat on the face of the riser. If there was originally an aux. tank in there, then you should either see a plate covering up where it used to be or the valve. It would be right between your legs if you are sitting in the pilots seat.

For EFI, you have to run both a supply & return line, and if you are going to incorporate the aux. tank into the system, you have to get an electronic tank selector valve. Any auto parts store should have those, they are anywhere from $25-100. They will have 4 ports on one side & 2 on the other, often you can call them a 6-port gas valve & the parts guy should be able to help you. The next thing you will have to have is an electric pump close to the tank. Elec. pumps (and EFI in particular) were designed for pushing fuel, not pulling it, so the closer to the tank, the better. You will have to run the supply lines from both tanks to the new selector valve & then a single line to the engine supply line. Same with the return lines. You want to make sure that the return line & supply line from the same tank are correctly hooked up or you will have some serious overflow/leaking problems when you run the larger tank.

You would use the same sending unit & you could use a vent line port on the aux tank for a return line. Look at the way that the EFI tank is run right now & just mimic it to the 6-port valve.

Here is a rough sketch of what your EFI should look something like & what original fuel lines look like. You are going to have to look close because the color didn't come through on my scanner, but the EFI drawing has both return lines & supply lines. The return lines don't go through the fuel pumps

Attached thumbnail(s)

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[Bulldawg44]

Thanks a bunch S bolt19, great information, and I sure appreciate the drawing as well. I am going to give it a try, thanks again

[Bully Bob]

And..,
Check with wildhorses.com (left coast)
They have the aux. tank all set-up for EFI., Incl. sender & mount. hardware.
(Most EB supply houses will have them)
Right coast would be Jeffs Br. Graveyard.