Fuel tank and pump setup with return style regulator.

Sean S.

Supporter
I have been researching and don't see a good option for using a return style regulator going into 2 fuel tanks. The only electric valve I can find uses plastic barb fittings. I found a few marine and aircraft valves, but I don't really like the thought of having to turn a lever, nor the way it looks.

My question is, has anyone tried to run an equalizing line between the tanks to allow the use of 1 fuel pump pulling from 1 tank and the regulator returning to the same tank? If so, please share any pictures you may have.

This sketch is what I am thinking.

Thanks

Sean
 

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Davidmgbv8

Supporter
Sean,
What is wrong with the electric Pollak valve. It is used in thousands of trucks in North America. Yes they are nylon reinforced plastic A friend just went thru all of this with a Jag MK2 sedan that converted to FI. He had to vent the second tank and join it to the main tank with a 1 1/4" line to get it to balance properly. Any line smaller they tried would not transfer fuel properly, especially when filling.
 

Sean S.

Supporter
Sean,
What is wrong with the electric Pollak valve. It is used in thousands of trucks in North America. Yes they are nylon reinforced plastic A friend just went thru all of this with a Jag MK2 sedan that converted to FI. He had to vent the second tank and join it to the main tank with a 1 1/4" line to get it to balance properly. Any line smaller they tried would not transfer fuel properly, especially when filling.
David,

I was looking at those valves. My worry is both the look of the valve and leakage around the barb fitting, although I could likely hide it somewhere. I'm also wanting to keep everything braided SS lines with AN fittings.

I was also thinking the equalizing line could be around 1/2", although you are correct about fueling the car which I did figure there would be a back and forth on each side of the car while fueling.

Sean
 

Ian Anderson

Lifetime Supporter
Pollack valves work well enough, I had one on my car…..no leaks!
it only has power use during the changeover, perhaps half a second.
With solenoids you have to have power to it to keep it open. My thought was I would rather not have a powered unit next to fuel!

With the system as you have drawn it will not work, you will also need to have an air bleed across the tanks top of one to top of other for air to move one way while fuel moves the other.
A half inch hose would work as the cross over fuel line while driving but be a bit slow when filling if you only fill from one side.

Also if you manage to puncture the cross over fuel line you have no way of stopping it till both tank contents are on the floor.

Better to draw the fuel upwards from the tank, like most production tanks, as opposed to drawing from the bottom…..if the fuel pip ruptures the fuel stays in the tank!

Ian
 

Davidmgbv8

Supporter
While braided lines are cool they are also overrated unless they are on a real race car. They are expensive, second difficult to cut and fit. Then clean out. God forbid that you ever get a pinhole leak on a fuel suction line it will drive you mad finding out why your car is running lean until you suck on the fuel line and get air and not fuel. I will be running Earl's vapor guard and protect from heat as needed with protective sleeving.

Any way my thoughts
 

Kyle

Supporter
I’m not familiar with how the RCR frame is set up, but when I do a GT40 build I’m planning 3/4 barb welded to the bottom of each tank, 3/4 equalizer line. With each having its own vent line. 3/4 line should be plenty for fueling.

With all aluminum mono like RCR tho this may be difficult.
 

Sean S.

Supporter
If I was to go forward with this, I would have each tank vented so there would be no cross vent necessary. The main reason I want the SS lines is the look, they are not difficult to work with in my opinion. I have also had several issues with lines and hose clamps leaking. I have had better luck with return style regulators vs internal in the pump and external. I have had several that needed readjustment if the car set for a couple weeks without driving it.

Kyle, you hit the main concern of my question. RCR's tanks set inside the chassis completely enclosed. Its not impossible to make something that can allow me to run a crossover line, but it would be difficult.

Sean
 

Bill Kearley

Supporter
Have a look at the old Ford dual tank type of switch as used in pick ups. Just select #1 or #2 tank. The switch will also send the signal from the chosen sending unit for your gauge. I used JIC fittings and push on on hose, good for 300 PSI.
 
I'll be doing EFI with large-ish surge tank. The idea of having 1/4 tank of gas, but at a down hill redlight and running out of gas doesn't sound appealing.

I'll be complicating the situation with multiple fuel pumps. Surge tank only returning to one tank, and the secondary tank (through intank pump) in the front (opposite of other tank) feeding the surge tank on demand only.
 
I've seen it and don't trust the gas formulators to add something that turns it into filter clogging mush a few years later. And honestly, with the low surface tension of gas, I have a hard time thinking it's that effective.
 

Sean S.

Supporter
I'll be doing EFI with large-ish surge tank. The idea of having 1/4 tank of gas, but at a down hill redlight and running out of gas doesn't sound appealing.

I'll be complicating the situation with multiple fuel pumps. Surge tank only returning to one tank, and the secondary tank (through intank pump) in the front (opposite of other tank) feeding the surge tank on demand only.


I haven't had any experience with using Surge tanks, but this looks like a solution to my problem. I don't see an easy way to run a crossover line through the bulkheads, also I don't think it will look good.

After researching a bit. I think I will run 2 pumps from the fuel tanks, each controlled individually by a switch. They will feed the surge tank with check valves inline, then the surge tank pump to carburetor and bypass PRV back to the surge tank. There are several options for the surge tanks with AN fittings so this should work very well for me.

Thank you for bringing the surge tank option to my attention Brian.

Regards,

Sean
 
Glad to help. I've been noodling on this for a while, and the shape of the GT40's tanks have been giving me pause as EFI fuel plumbing cannot tolerate sucking vapor.

In my cobra, I incorporated the surge tank into the main tank, and the return fuel fed a venturi pump to keep the inner 1 gallon tank full.
 

Bob

Supporter
Hello,

Have a gallonswirl tank out of my 40.
Has a newer wet pump with regulator.
Both my low pressure pumps fed in to float control valves thru the top.

Ran a Holley with it turned down.
Believe it's about 6 inches wide and maybe a foot tall.
Has side plates on the bottom to attach.
Was mounted behind ps fuel tank in hall.
Will locate it if it would work for ya.

Pay the shipping...
 

Sean S.

Supporter
Hello,

Have a gallonswirl tank out of my 40.
Has a newer wet pump with regulator.
Both my low pressure pumps fed in to float control valves thru the top.

Ran a Holley with it turned down.
Believe it's about 6 inches wide and maybe a foot tall.
Has side plates on the bottom to attach.
Was mounted behind ps fuel tank in hall.
Will locate it if it would work for ya.

Pay the shipping...


Thank you for the offer, yes I would be very interested.
 

Bob

Supporter
Needs cleaned up but works good.
 

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Hey Sean! Wanting to join in on this fuel discussion....
I am working out my fuel system for my RCR right now as well and stumbled on this recent post as well as your posting in the Fuel technical forum... (the car shows up this fall hopefully)

I was considering the exact same solution you were previously with the equalizing line. However I read you opted for two low pressure pumps feeding each tank into a swirl pot. I am doing EFI so I will definitely need a swirl pot/surge tank like you chose.

I too was having doubts about the equalizing line concept.
I think it is a good point that if the line was damaged or started a leak there would be no stopping it (vs a pump pulling fuel up out of a tank)
Also I plan on doing lots of performance driving, so I think I would also worry about additional fuel starvation as now g forces can push fuel side to side away from the primary tank on long turns. Of course a small check valve may remedy this... and maybe it would not even be an issue as there will be a swirl pot and a small equalizer line can't flow much fuel...

Regardless I think I have also abandoned the concept.

I am now considering a low pressure "transfer pump" feeding the other "primary" tank. The transfer pump could just be on a manual switch. I would push fuel over as needed. The primary tank would transfer fuel to a swirl pot which would feed a high pressure pump and regulator for EFI. Currently I have the regulator sketched out to feed back to the surge tank. I would then have a return line also back to the primary tank to prevent an overflow. Sounds like a lot of lines though...

Your solution also interests me as it is a slightly different take. However I have a few questions about it.
I am not sure I am understanding how your fuel pumps will be switched on/off as needed. Either they will be always on with a return line to prevent overflow... or you have switches with floats. Would you please explain?

Side question... were the aeromotive low pressure pumps specifically rated to scavenge air momentarily upon turning air as they suck fuel up line? I am not finding much about it. Not too worried about it, just surprised to not hear more about this. Typically fuel injection pumps are fully submerged these days to mitigate dry starts. Would you please share the part #'s you chose? My fuel injection system stock had a fuel pump rated for 255 lph so trying to exceed this # and let my regulator do its thing.
 
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