Sniper Efi dual tank plumbing

[Grey owl]

I am interested in the correct gas line plumbing for a Sniper Efi on a Bronco with dual tanks. It certainly must be more complicated considering both tanks will need separate fuel pumps. I guess the fuel tank switch can be used to turn one pump on and the other off.
I have tried 3 different carbs and settled on the 650 DP Brawler. It works great but the trend seems to be moving towards the Sniper.
What is your opinion ??

 

[EPB72]

If undeed moving to efi 1 option run off the main tank with supply and return (would run in tank but that’s me) and use auxiliary as gas can and plumb wire in a transfer pump, if running both tanks then would need a supply and return th be switch , not sure but pollack had a 6way that preformed that on the gm square bodies,,
,,

 

[Broncobowsher]

Sooooooo many different ways of doing this. Most will work fine.

Of my dual tank EFI setups I have done, First one was a modified transfer pump design. I had an accumulator of about 1-quart (people have done this with a spin of fuel filter but often screw up the plumbing with a bad 3-port and a T layout instead of a proper 4-port. The idea is 2 seperate loops mixed at the accumulator. High pressure pump off the accumulator to the EFI and return to the accumulator. Then a low pressure pump (P4070 is my go to pump for this stuff) pulls out of the selector valve just like a carb setup, but only a return to the main tank. In this setup you run the main tank, get low and switch to the aux tank. The low pressure pump moves fuel out of the aux, through the accumulator, returns to the main tank. It is simple, built that way when I did hard off-roading and needed good fuel delivery even at bad angles. It is flawed in the driver has to pay attention to what they are doing or risk overflowing the main tank. A bit of a pump safety if you forget you are transfering fuel the pump will only run dry until the accumulator runs out,

The second time I did it I changed and went to a single high pressure at each tank. Street truck and not really worried about fuel delivery at severe angles. This ran an electric 3-port LOW PRESSURE selector valve. The simple solenoid version that was wired to the aux tank fuel pump. Doesn't make sense yet, let me keep going. The pumps were wired to a SPDT relay. Common was the pump wire off the Sniper. Normally open ran the main tank. Normally closed ran the aux tank (and selector solenoid). Since the pumps have built in check valves, either one will pressurize the fuel filter and lines to the EFI. The return goes to the selector valve and that directs which tank fuel returns to. Relay off, main tank pumps runs, aux pump check valve holds closed, EFI fed and return goes to the selector valve that directs it back to the main tank. Relay on, main pump goes off and aux pump now runs. Main pump check valve holds. Fuel through EFI and return goes to selector valve. Since the valve is wired with the pump, if the aux pump is running the return is going to the aux tank. Both tanks I put a new pickup line and filter sock on and used the factory pickup (missing the filter sock) as the return. The factory fuel system from the selector valve to the tanks was completely factory, just flowing backwards. This prevents the fuel tank transfer overflow issues built into my first design.

 

[Grey owl]

ThankThanks

Sooooooo many different ways of doing this. Most will work fine.

Of my dual tank EFI setups I have done, First one was a modified transfer pump design. I had an accumulator of about 1-quart (people have done this with a spin of fuel filter but often screw up the plumbing with a bad 3-port and a T layout instead of a proper 4-port. The idea is 2 seperate loops mixed at the accumulator. High pressure pump off the accumulator to the EFI and return to the accumulator. Then a low pressure pump (P4070 is my go to pump for this stuff) pulls out of the selector valve just like a carb setup, but only a return to the main tank. In this setup you run the main tank, get low and switch to the aux tank. The low pressure pump moves fuel out of the aux, through the accumulator, returns to the main tank. It is simple, built that way when I did hard off-roading and needed good fuel delivery even at bad angles. It is flawed in the driver has to pay attention to what they are doing or risk overflowing the main tank. A bit of a pump safety if you forget you are transfering fuel the pump will only run dry until the accumulator runs out,

The second time I did it I changed and went to a single high pressure at each tank. Street truck and not really worried about fuel delivery at severe angles. This ran an electric 3-port LOW PRESSURE selector valve. The simple solenoid version that was wired to the aux tank fuel pump. Doesn't make sense yet, let me keep going. The pumps were wired to a SPDT relay. Common was the pump wire off the Sniper. Normally open ran the main tank. Normally closed ran the aux tank (and selector solenoid). Since the pumps have built in check valves, either one will pressurize the fuel filter and lines to the EFI. The return goes to the selector valve and that directs which tank fuel returns to. Relay off, main tank pumps runs, aux pump check valve holds closed, EFI fed and return goes to the selector valve that directs it back to the main tank. Relay on, main pump goes off and aux pump now runs. Main pump check valve holds. Fuel through EFI and return goes to selector valve. Since the valve is wired with the pump, if the aux pump is running the return is going to the aux tank. Both tanks I put a new pickup line and filter sock on and used the factory pickup (missing the filter sock) as the return. The factory fuel system from the selector valve to the tanks was completely factory, just flowing backwards. This prevents the fuel tank transfer overflow issues built into my first design.

Thanks fof that detailed description, the second tank adds a whole new layer of engineering, plumbing and expense. I certainly appreciate your insight to that particular modification.
Now its just a matter of deciding if the benefits of EFI are worth the cost. I guess the other option is to put in a new 23 gallon tank and eliminate the aux tank.

 

[Broncobowsher]

I guess the other option is to put in a new 23 gallon tank and eliminate the aux tank.

Yes, that is the way to do it. After going to the 23 gallon main, the aux started becoming a pain. I was stubborn and kept it because my first Bronco only had the main tank and I could never put a larger one on (welded on hitch). My shopping for the last bronco required dual tanks. Then went 23 gallon, it was plenty. Never drove it to the point I could go through that much and didn't want to stop at least once.

 

[Grey owl]

If undeed moving to efi 1 option run off the main tank with supply and return (would run in tank but that’s me) and use auxiliary as gas can and plumb wire in a transfer pump, if running both tanks then would need a supply and return th be switch , not sure but pollack had a 6way that preformed that on the gm square bodies,,
,,

 

[Grey owl]

If undeed moving to efi 1 option run off the main tank with supply and return (would rnk but that’s me) and use auxiliary as gas can and plumb wire in a transfer pump, if running both tanks then would need a supply and return th be switch , not sure but pollack had a 6way that preformed that on the gm square bodies,,
,,

Interesting idea using the auxiliary tank as storage with a pump draw it down.
Thanks

 

[AZ73]

I have a 23 gal tank with an external Carter LP pump that draws through a 20 micron filter. It runs to a GM electric tank switch. After that is a Bosch HP pump through a 10 micron filter to the Sniper. The Aux tank is gravity feed to the switch which just means it's being "pulled" with gravity assist with the "Pusher" Bosch bump. While the GM swich will also control the fuel gauge sending units, I'm running 2 fuel gauges so I bypass it. My Alt tank switch turns off the Carter when engaged. The Bosch is running main and alt. More complicated that plumbing the aux to refill the main, but my setup allows different fuel to run in each tank.

 

[ntsqd]

One way to prevent a fuel spill when only returning to one tank is to vent the aux tank into the main tank only. Over-fill either tank and the vent line allows fuel to move to the other tank.

Those 6 port Pollack valves don't have the best reputation. The 3 port valves are considered to work a lot better.
If you really want a six port valve then here you go: https://www.andair.co.uk/product/duplex-fuel-selector-fs2020-d2/ (as used by @lars )

Grandad used a 3 way valve much like the stock EB valve on his dual tanked '72 F100. He put an eccentric on the valve's stem and mounted a micro-switch such that the eccentric would move the lever and change which sender was reporting to the gauge.

 

[Broncobowsher]

Grandad used a 3 way valve much like the stock EB valve on his dual tanked '72 F100. He put an eccentric on the valve's stem and mounted a micro-switch such that the eccentric would move the lever and change which sender was reporting to the gauge.

I took the face off a spare fuel level gauge and put it on the water temp gauge. Since I was running an aftermarket temp and oil gauge, it made the unused stock temp gauge another fuel gauge. 100% factory parts, just mixed and matched. You could see what either tank was doing at any time. No switching needed.

 

[ntsqd]

MISF did that for all three of his Scout's fuel tanks. Even placed them in the dash L - Center - R. I seem to recall that he had to cut up and piece together a couple of the overlay-bezels to make it all work.