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Discussion Starter · #1 ·
I am thinking about adding a 2nd fuel tank I might end up using it for SVO/WVO but for now it is for extending my range. I am thinking about a manual 3 way valve that I can switch myself whilst driving and to keep it simple wondered if looping the fuel return causes any problems? The only one I could really think of was getting air out of system but my fuel filter has a bleed nipple on top for that. So what are the pro's & cons. What have I missed?

Gaza
 

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Not sure what you mean by looping the return. If you don't have a positive way to direct the fuel returning to the tank you are drawing from you could end up overflowing the other tank. Another way to do it is put an electric pump on the second tank and use it to transfer fuel to the main tank. keep the return going to the main tank only. You just have to remember to watch the main tank level when you are transferring and turn the pump off when it's full or the reserve tank is empty. Put a red light in the cab to remind you the pump is on. Tie an overflow line in the fill line for the main tank to the reserve tank so if you forget the fuel from the main will go to the reserve tank if it reaches the level of the overflow.
 

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Another way to do it is put an electric pump on the second tank and use it to transfer fuel to the main tank. Keep the return going to the main tank only.
^ What I did, works great.
It helps also to have a stopwatch and time how fast the transfer occurs, so you have an approximate time per gallon of fuel transfer. Just keep the number in your head so you can run the pump for 10-15 minutes at a time and know how much fuel you moved.

There available 6 port fuel selector valves (two in + one out, one in + two out for return), get one for a 70's Chevy pickup truck.
 

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Looping the return on both tanks is definately not recommended. The air is not easy to get out.

Your fuel in the tank gets aerated from sloshing around, and though not noticeable with a return to tank can compound with the looped return.
Another reason for return to tank is because the fuel gets hot circulating through the IP. On diesel this is not good.

I suggest using 2 3-port valves or one 6 port
http://www.andersonbrass.com/SELECTOR_VALVES.PHP
 

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If you are running diesel in both tanks the above methods work quite well. If you are running diesel in one and WVO in the second I would advise using two manually operated valves; one for the fuel going in and one for the return line. The electrics work but you will be initially dumping the contents of the fuel filter and and all of the return lines into the tank that you are switching over to each time you switch tanks. This may not amount to a lot but will be depending on firing up on diesel containing a high percentage of WVO which may cause problems in colder climates.
 

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The M37 that I am building has 2 fuel tanks. I have (2) 3 position valves plumbed. One valve selects the tank to be drawn from, the other valve selects the tank for the return line.

Paul
 

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6 way valve

J C Whitney has a 6 way valve (from Ford Diesel pickups) at reasonable price.
One switch then switches between tanks.

I prefer a main tank, and use an electric pump from second tank to fill main. I ran out of fuel once with dual tanks (variation in senders).
It bites to run out of fuel with a full tank on truck in another tank. Lesson learned.
Wayne
 

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Discussion Starter · #8 ·
Thanks for the replies.
By loop return I mean the return goes not back to the fuel tank but straight back into the feed, through the filter and back to the I/P.

I have a 6 way pollack but don't really like the look of it. I would prefer a brass manual valve. I had thought about using 2 i.e one for return but the KISS principle kept making me think one valve. I had also thought about pumping 2nd tank into main with electric pump, but overfilling main tank and previous trouble with electric pump made me think again. I have piston pumps on my 6BT and 4BT so would prefer to use these. Saying that I am probably going to keep an electric pump inline to ease bleeding.
Paul are you using manual valves or electric?
I think the replies have convinced me to go two 3 way manual valves.
I would imagine running out of fuel with one of your tanks full to be a real bummer, did you have seperate gauges?
Roverhybrids thanks for the link those valves look like quality stuff, I presume you have used these?

Gaza
 

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Thanks for the replies.
By loop return I mean the return goes not back to the fuel tank but straight back into the feed, through the filter and back to the I/P.

I have a 6 way pollack but don't really like the look of it. I would prefer a brass manual valve. I had thought about using 2 i.e one for return but the KISS principle kept making me think one valve. I had also thought about pumping 2nd tank into main with electric pump, but overfilling main tank and previous trouble with electric pump made me think again. I have piston pumps on my 6BT and 4BT so would prefer to use these. Saying that I am probably going to keep an electric pump inline to ease bleeding.
Paul are you using manual valves or electric?
I think the replies have convinced me to go two 3 way manual valves.
I would imagine running out of fuel with one of your tanks full to be a real bummer, did you have seperate gauges?
Roverhybrids thanks for the link those valves look like quality stuff, I presume you have used these?

Gaza[/QUOTE

Gaza, my 2 valves are manual with 3 positions each indexed with a detent. The valve is made by Weatherhead. My local NAPA got them for me overnight, so its a shelf item.

Paul
 
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