Big Fuel Tank (1 Viewer)

[Siege]

Has anyone looked into utilizing the readily available electronics from a Ford dual tank truck to handle the switching from one tank to the other?

It consists of two tanks with a sending unit/fuel pump in each tank, electrical switch to swap power/signal from one to the other and a mechanical selector valve that will block off the return line to the opposing tank when fuel is sent through it from the other.

Here's an electrical diagram the dual tank setup:


Some adaptation is required but at least all the parts can be pulled off trucks plentiful in US junkyards.

 

[greentruck]

Siege,
Interesting diagram. A couple of questions if you or anyone else knows.

I'm not quite sure where the mechanical selector valve is tied into the electrical diagram here? My guess is at the fuel tank selector switch (same part controls both electricity and fuel.) IIRC, when looking through parts, either Ford or GM had a combined valve set-up like that which seems to have come into use since fuel injection became widely used vs the old fluid only tank selector valves.

Second, I see there's fuel pumps in both tanks, plus an external fuel pump. I'm guessing low pressure out of the tank, then the primary pump boosts it to high pressure, maybe? Anyway, I presume it would also work with two in-tank pumps that deliver full fuel pressure without the need for an external pump. That could be handy if it worked, as it would hopefully allow on the fly changeover with fuel injection on the 80, which might be iffy with a fluid only tank selection valve. This presumes that the aux tank is set-up to feed the fuel line independently from the main tank like Ford does it and NOT be a subtank that pumps into the main like Toyota does.

 

[alia176]

When I did a rough paper napkin schematic, it seemed to me that feeding the engine with dual pumps is a piece of cake. At first I thought that a switching valve would be needed but in order to keep it simple, I was going to plumb the outlet from both pumps into the FPR line (engine feed) in the engine.

As far as the return, I was going to just "try and see" what would happen if I left that one alone. Another words, here's what I'd do: run the main tank dry, switch over to the aux tank. The return would simply go to the empty Main tank.

The 80 has a two speed pump and that too was going to be simple. Basically, a simple resistor is brought in for "low" speed operation. Again, my plan was to run the Aux pump from the same wire that runs the Main pump. Regardless of what kind of in tank fuel pump my donor Aux tank has, that pump will run in two speed mode as needed.

I just need to make sure that the Aux pump has similar output as the Main pump but given that most SUVs (V6 or I6) have similar displacement, I think the pumps will have similar pressure/flow numbers.

 

[86tuning]

^^ problem with that setup is that the aux tank would quickly empty into the main tank anyways thru the return line. Even at full throttle, full load, there is a lot of fuel flowing back thru the return line. So when you feel the engine hiccup or run lean due to lack of fuel, you'd switch back to the main tank pump...

Might be easier just to use an electric pump from a carbureted application to pump it into the main tank. Lower pressure, less chance of leaks, no need to run a fuel pipe all the way to the engine into the fuel filter.

Hence my comment a few pages back about a 'jet pump' which is what toyota uses in their saddle-tank vehicles to transfer gas from one side of the saddle to the other. Some RWD cars with a propshaft and exhaust running down the middle of the car require the fuel tank to be saddle shaped, with a big notch in the bottom, so that fuel cannot flow from one side to the other except under extreme cornering loads

The jet-pump is a suction pump that runs off the return line from the pressure regulator. Fuel flowing thru a jet will draw the fuel from the other side, like how a paint spray gun draws paint up using air flowing thru a nozzle.

The suction can draw the fuel from the aux tank into the main tank automatically, much like a gravity feed design, but without the gravity feed problems. Not sure what the maximum lift would be, but it doesn't have to be much to get the fuel siphon started. Leaks won't empty the tank like a gravity setup. And fuel would automatically slowly transfer from the aux tank into the main tank.

I'm guessing the overflow would have to somehow flow back to the aux tank, perhaps thru the filler neck? How does the factory aux tank deal with overflowing the main tank?

I saw a photo somewhere (probably on 'mud) of a Y shaped filler neck, where you'd just shove the nozzle to one side or the other to fill the main or aux tank. No knob to pull or valve to deal with.

 

[Siege]

Siege,
Interesting diagram. A couple of questions if you or anyone else knows.

I'm not quite sure where the mechanical selector valve is tied into the electrical diagram here? My guess is at the fuel tank selector switch (same part controls both electricity and fuel.) IIRC, when looking through parts, either Ford or GM had a combined valve set-up like that which seems to have come into use since fuel injection became widely used vs the old fluid only tank selector valves.

Second, I see there's fuel pumps in both tanks, plus an external fuel pump. I'm guessing low pressure out of the tank, then the primary pump boosts it to high pressure, maybe? Anyway, I presume it would also work with two in-tank pumps that deliver full fuel pressure without the need for an external pump. That could be handy if it worked, as it would hopefully allow on the fly changeover with fuel injection on the 80, which might be iffy with a fluid only tank selection valve. This presumes that the aux tank is set-up to feed the fuel line independently from the main tank like Ford does it and NOT be a subtank that pumps into the main like Toyota does.

The selector valve is purely mechanical and operates off the pressure being fed into it. When you toggle the switch on the dash from one tank to the other then the change in pressure going into the selector valve will close off the opposing tank feed and return.

You are correct that it uses an external high pressure pump and two low pressure pumps in tank. I'm not sure if it would affect the operation of the selector valve being fed from high pressure pumps.

 

[Siege]

Hence my comment a few pages back about a 'jet pump' which is what toyota uses in their saddle-tank vehicles to transfer gas from one side of the saddle to the other. Some RWD cars with a propshaft and exhaust running down the middle of the car require the fuel tank to be saddle shaped, with a big notch in the bottom, so that fuel cannot flow from one side to the other except under extreme cornering loads

The jet-pump is a suction pump that runs off the return line from the pressure regulator. Fuel flowing thru a jet will draw the fuel from the other side, like how a paint spray gun draws paint up using air flowing thru a nozzle.

The suction can draw the fuel from the aux tank into the main tank automatically, much like a gravity feed design, but without the gravity feed problems. Not sure what the maximum lift would be, but it doesn't have to be much to get the fuel siphon started. Leaks won't empty the tank like a gravity setup. And fuel would automatically slowly transfer from the aux tank into the main tank.

I'm guessing the overflow would have to somehow flow back to the aux tank, perhaps thru the filler neck? How does the factory aux tank deal with overflowing the main tank?

I looked up the jet pump you described and it definitely seems like a great idea. I bet you could "tune" the flow from the aux tank by adding a restrictor to the aux tank feed line to prevent overflow.

Best of all it's purely mechanical.

Diagram attached for everyone.

 

[Photoman]

I did not read this whole thread so disregard if this information is irrelevant.

I had a dual tank same fuel pressure system for several years. I modified a 45 gallon Long Ranger aux. tank by fabricating and welding on a flange so a stock fuel pump and fuel sending unit could run from the second tank. In other words two stock pressure fuel systems that were the same. It is a very nice system in that if one fuel pump fails the cruiser can still run on the other.

The two pressure lines from the fuel pumps can be teed together since both fuel pumps have the same pressure and a check valve built in the pumps (at least stock 1997 pumps). There is always pressure in the system this way so almost no hesitation when switching pumps/tanks. All that needs to be switched is the return fuel lines. A NAPA valve #2-2198 can be used for this using only one position on the valve.

A simple single pole double throw relay (SPDT - or sometimes called a 5 pin relay) can be used to switch the fuel senders. I used pins 30 to 87a for the stock tank sender, and 30 to 87 for the auxiliary tank fuel sender.

With a simple flip of toggle type switch power is sent from one pump to the other, the returns are switched, and the fuel gauge is switched.


Bill

 

[86tuning]

I looked up the jet pump you described and it definitely seems like a great idea. I bet you could "tune" the flow from the aux tank by adding a restrictor to the aux tank feed line to prevent overflow.

Best of all it's purely mechanical.

Diagram attached for everyone.

Picture is worth a thousand words. Thanks for clarifying with the diagram!

 

[greentruck]

86tuning & Siege,
That jet pump is a great idea. Those folks thinking about a gravity feed system should consider it. Heck, that may be what I go with, as it seems very bulletproof and simple.

I also wonder about return. This will obviously come into play when both tanks are full. The jet pump would have to just keep pumping -- I presume -- pushing the fuel back to the aux tank until the main is drawn down enough to allow the aux to begin emptying.

Essentially what it does is keeps things level, so it will always be seeking that until the aux runs dry and breaks the siphon.

Bill,
Those are helpful comments. I think no one cleared that up previously, so good to know your slick set-up works well. I really like the redundancy, too, which might be one reason to NOT go with the jet pump.

So many options in this thread. I love it.

 

[86tuning]

Bill,
Those are helpful comments. I think no one cleared that up previously, so good to know your slick set-up works well. I really like the redundancy, too, which might be one reason to NOT go with the jet pump.

So many options in this thread. I love it.

Yes. A neat solution, dual pumps and a valve to put the return line to the correct tank. Where's the cleanest spot to tee in the feed? At the filter?

 

[Photoman]

Yes. A neat solution, dual pumps and a valve to put the return line to the correct tank. Where's the cleanest spot to tee in the feed? At the filter?

Ya, I cut the rubber hose to the "in" side of the filter. Both tanks then feed through the stock filter. Real easy to extend the rubber hose to wherever you want for the tee. I mounted the switch valve by the charcoal canister for the return.

Bill

 

[neal0124]

I wonder if this Trax-II setup would be able to be fitted for fuel level monitoring and transfer duty. I believe on their setups it is designed to automatically transfer fuel into the main tank when it drops below 1/4 and fills until it reaches 3/4 full.

http://www.transferflow.com/trax-ll.html

 

[alia176]

I wonder if this Trax-II setup would be able to be fitted for fuel level monitoring and transfer duty. I believe on their setups it is designed to automatically transfer fuel into the main tank when it drops below 1/4 and fills until it reaches 3/4 full.

http://www.transferflow.com/trax-ll.html

It's also designed for a much larger tank (min 37 gal) and I'm thinking the price will be over $400. As detailed above, George's ECU + simple pump + fancy OEM subtank button = less than $150

 

[scottryana]

Just bought a Supra and a 1UZFE, so 80 projects are going on the back burner.

I have the dual filler neck I just bought unopened if anyone wants it I will do $325 shipped.

Thanks!
Ryan

 

[greentruck]

What does something like this cost?

Sent from my Nexus S using IH8MUD

The high capacity Long Ranger tanks I've seen priced in the US recently have all been well north of $1000, maybe $1400?

 

[Wheelingnoob]

Still Playing around with this. I am going diesel now so its going to be a bit diffrent.

What size fuel line does the 80 series have? Do not want to take it apart to measure if someone knows.

 

[Douglas S]

Still Playing around with this. I am going diesel now so its going to be a bit diffrent.

What size fuel line does the 80 series have? Do not want to take it apart to measure if someone knows.

1HD-T 80 has 10mm supply, not sure about return.

 

[Wheelingnoob]

So to revive this again.

I think I am going to try the 4runner tank I have at the side of my house. Its benefits are its free, its got a Toyota level sender in it, its a bracket mount so no straps to worry about and its 17 gallons so more than OEM aux tank but less less weight than the 25+ gallon tanks.

I'm going with a diesel engine now so no issue sorting out pumps and so forth, I'll remove the pump and put a pick-up tube in the tank to draw fuel. I think I may use a ford diesel dual tank selector valve. This way I do not need to transfer fuel from one tank to another I can just run off each tank at a time. I'm also going to see if I can hook the level gauges and low fuel lights from each into the selector switch so I have a working fuel gauge for each tank with the OEM instrument cluster.

With the diesel I will have effectively double my range on a singe tank so the 25 gallon stock tank and the 17 gallon 4runner tank will give me about 700-800 miles of range on road and about 500 off. If I need more I can put my 3 jerry cans on the back.

 

[scottryana]

Jeremy,

Your dual filler neck is expected to be delivered 02/05.

Thanks!

So to revive this again.

I think I am going to try the 4runner tank I have at the side of my house. Its benefits are its free, its got a Toyota level sender in it, its a bracket mount so no straps to worry about and its 17 gallons so more than OEM aux tank but less less weight than the 25+ gallon tanks.

I'm going with a diesel engine now so no issue sorting out pumps and so forth, I'll remove the pump and put a pick-up tube in the tank to draw fuel. I think I may use a ford diesel dual tank selector valve. This way I do not need to transfer fuel from one tank to another I can just run off each tank at a time. I'm also going to see if I can hook the level gauges and low fuel lights from each into the selector switch so I have a working fuel gauge for each tank with the OEM instrument cluster.

With the diesel I will have effectively double my range on a singe tank so the 25 gallon stock tank and the 17 gallon 4runner tank will give me about 700-800 miles of range on road and about 500 off. If I need more I can put my 3 jerry cans on the back.

 

[Wheelingnoob]

Jeremy,

Your dual filler neck is expected to be delivered 02/05.

Thanks!

Thanks again! Look forward to see the dyno results for that MAF.