Dual tanks and EFI setup

How do you guys route your return EFI lines in regards to dual tanks? Do you have a return line to each tank? Did you modify your setup to return fuel to main tank only and use the aux. tank to fill the main? What "switching" did you use between the tanks?

ELECTRIC FUEL TANK SELECTOR VALVES
B.C. BRONCOS TECH LIBRARY
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for a wiring and plumbing diagram in PDF format!

These electric fuel tank selector valves replace the old manual tank selector under your seat for easy, trouble-free operation. The 3-port valve is the solution for carburated vehicles. The 6-port valve is the answer to the dual tanks dilemna for EFI-equipped vehicles, as it switches both the supply and return lines simultaneously. Best of all, either can be easily wired to the existing fuel gauge selector switch on your dash, so you can switch switch the fuel gauge between tanks at the same time you switch tanks for fuel delivery.


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6 Port Fuel Tank Selector Valve (EFI) $79.00
Wiring kit $21.00

...what he said. I've got a NWMP 23 gallon tank in back which came with vent lines for the EVAP system. Since my truck doesn't have evaporative emissions controls, I used on as the return line port. On my aux tank I yanked the sender, drilled a hole in its cover plate, then silver soldered a piece of 5/16" stainless steel tubing into it to create the return line port. Nice to have 30+ gallons on board, especially with my gas hog.

You need some type of 6 way port. I used the BC 6 port electric switch with great results. You can see pics of it in my EFI fuel system install tech article.

I welded a 1/4 pipe fitting to the side of my stock rear tank and fed the return line to it. For the aux. tank, I used an elec. fuel pump(NAPA) to dump fuel into the main tank when it got low. You will need to weld a fitting to the main tank for this too. I run my EFI system off the main tank, so there aren't any leaky valves to mess with.

Forgot about Chuck's fuel valve

I just have to be different...

I was running an electric fuel pump with the carb set up, so I recycled it. Both tanks draw fuel up to the selector valve just like they did when new (ony new line). From there the Fuel goes to an accumulator. The accumulator overflow all runs back to the rear tank through the evap fitting on the NWMP 23 gallon tank.

The high pressure fuel pump is under the hood on the drivers inner fender. It draws fuel in from the accumulator and the injector return also goes into the accumulator.

For gauges, I replaced the face of the stock temp gauge with the face from another old fuel gauge that didn't work. The windings inside the temp gauge are the same as the fuel gauge. No more switching to see how much is in each tank. I can read both gauges at once.

Just draw down the main to under half, switch to aux. Watch one gauge go down as the other goes up. Then switch back to the main.

With my set up, I didn't have to buy any extra valves or pumps (already had the carb elecrtic pump).

[quote author=Broncobowsher link=board=5;threadid=15441;start=0#msg116927 date=1048186041]
I just have to be different...

I was running an electric fuel pump with the carb set up, so I recycled it. Both tanks draw fuel up to the selector valve just like they did when new (ony new line). From there the Fuel goes to an accumulator. The accumulator overflow all runs back to the rear tank through the evap fitting on the NWMP 23 gallon tank.

The high pressure fuel pump is under the hood on the drivers inner fender. It draws fuel in from the accumulator and the injector return also goes into the accumulator.

For gauges, I replaced the face of the stock temp gauge with the face from another old fuel gauge that didn't work. The windings inside the temp gauge are the same as the fuel gauge. No more switching to see how much is in each tank. I can read both gauges at once.

Just draw down the main to under half, switch to aux. Watch one gauge go down as the other goes up. Then switch back to the main.

With my set up, I didn't have to buy any extra valves or pumps (already had the carb elecrtic pump).
[/quote]
Good Idea! Can you send some more info or pics?

What part of the set up do you want more info on?

I forgot to mention. I am running 4 filters with the 2 pumps
1 (x2) prefilter for the feed from each tank
1 prefilter for the HP fuel pump
1 good EFI filter to keep the injectors clean

That required 23 hose clamps to install.

I would like to know more about your plumbing, what "accumulator you are using, and what EFI pump you are using

The accumulator is an old coleman propane bottle that has 3 bolt welded on top and on one the side. The bolts were drilled out and tapped for ¼” pipe thread.
The fitting on the side goes to the fuel injection pump. The top 3 connect to the feed from the tanks, return to the main tank and return from the fuel injection.

I have no idea what the pump is. It came with the Holley Projection when I got it used. It has been running for a couple years problem free. I have another pump in the back that was given to me as a spare.

In a pinch, I could alter a few connections and bypass either pump. It should run (although badly and lean) off just the carb pump. I have seen throttle body fuel injection run on as little as 3 PSI. The other pump should be able to draw from the tank. Just might have vapor lock problem trying to pull gas that far with the high pressure pump.