can 2 6 gal tanks be tied together or 'tee-d'

[warrior1]

i am working on my buddys boat and he asked if 2 6 gallon tanks could be tee-d together to draw fuel from both at the same time in an effort to balance the weight. the boat is a 15ft bass boat and runs a 1975 115 hp. we are trying to keep the boat balanced while fishing. thanks.
i dont see why it would not work, i just dont know if there is not going to be enough suction from the fuel pump for both lines. kinda like when you try to use 2-3 straws in a drink.

 

[CATransplant]

Re: can 2 6 gal tanks be tied together or 'tee-d'

You probably could do that OK, but I can forsee one problem. When you use separate tanks and hose setups, you always know when you've burned half your fuel. It's a good thing to know. If you're sucking from both tanks at the same time...well...you don't know unless you keep checking the guages.

6 gallons of gas weighs about 36 lb. Personally, I don't see that as that much of a balance issue.

 

[warrior1]

Re: can 2 6 gal tanks be tied together or 'tee-d'

we have thought about the fuel level issue. running one tank at a time you do kinda have a "fuel check" at 6 gals. these are the 6 gal tempo see through tanks.
as for balance, this boat is one of those narrow 70's model bass boats.
he weighs 225 and with both live wells on the drivers side, it causes the boat to list. we have tried to offset this by having the batteries on the pass side.
i see what you meanthough by 36 lbs not being a big deal . just any little bit to help the balance.
thanks.

 

[CATransplant]

Re: can 2 6 gal tanks be tied together or 'tee-d'

Well, if you do decide to tee the things together, you can find nice brass hose Tees at the hardware store. I'd use them, rather than the plastic ones, just for strength's sake. You should be able to put the bulb on the single line that goes to the engine, but use a good one, not those cheapo Tempo bulbs. I'm sure the engine will pump the fuel OK from both tanks. The only problem I can forsee is if one of the tanks empties before the other. Then...you'd have the fuel pump sucking air. A little bit of a list might make that happen. If it did, you could clamp off the line to the empty tank with a pair of vicegrips, I suppose.

Watch your fuel levels, though. If it were me with one of those gas hog outboards, I believe I'd put a full 3 gal. tank up somewhere for emergency use. I'm just sayin'...

 

[ezeke]

Re: can 2 6 gal tanks be tied together or 'tee-d'

All other things being equal, two tanks of the same fuel sitting side by side, and connected to a common line, should always be at the same level automatically.

 

[F_R]

Re: can 2 6 gal tanks be tied together or 'tee-d'

That is correct, once one sucks dry, you are out of gas even if the other one were half full. However, there is a proper way to do it to prevent that. Use a 3 way valve made for the purpose instead of a T. With that, you control which tank it is drawing from. Marine stores and shops have them.

Edit: Exeke and I were typing at the same time. I agree with what he said in theory. But if there is any more resistance in one line than the other, it will upset the balance. The right way is still with switchable valve.

 

[tashasdaddy]

Re: can 2 6 gal tanks be tied together or 'tee-d'

i agree with the theory, but there are complications, vents open the same, etc. i agree with F_R 3 way valve.

 

[ezeke]

Re: can 2 6 gal tanks be tied together or 'tee-d'

"All other things being equal" is up to the installer. That of course includes resistance of any kind.

The fluid dynamics are not my specialty, but I would guess that you could balance two identical tanks with a larger line between the tanks than the one leading to the motor.

We have a lot of multi-tank installations for heating oil around here because you get a price break. The tanks are 275 gallons each and can maintain equilibrium while they are being filled. It is all in the design.

 

[Silvertip]

Re: can 2 6 gal tanks be tied together or 'tee-d'

I whole heartedly agree with F_R. Hoses being exactly the same length, banking turns, differences in fuel pickup screen density, and people moving about in the boat makes doing this without a fuel selector valve very "ify". As F R mentioned, when one goes dry you are out of fuel regardless how much is in the other tank. You could also not prime the engine if you only used one primer bulb after the "T" should one tank be dry. Use a quick connect on each tank. Run one tank out and switch the hose. Couldn't be cheaper and simpler.

 

[fdmsiv]

Re: can 2 6 gal tanks be tied together or 'tee-d'

Put some ball valves at the ends of the tee, that way you can draw from one tank at a time, or both.

Even if you move the tanks, as the fuel is used you are going to be right back where you started. You may start off with no list, but after a little run you will end up with a list.

 

[tashasdaddy]

Re: can 2 6 gal tanks be tied together or 'tee-d'

why not just buy a 12 or 18 gallon tank and center it in the boat.

 

[warrior1]

Re: can 2 6 gal tanks be tied together or 'tee-d'

well, thanks for all the input. and for all the reasons specified above, i am just going to tell him to run one tank at a time. balance be damned!!
problem solved.
as for using a bigger tank, it would not fit as well as the dual 6 gallons.

as always, thanks for all the time, help and suggestions.

 

[jay_merrill]

Re: can 2 6 gal tanks be tied together or 'tee-d'

I have done this - sort of. I once had two 12 gallon saddle tanks hooked to a fuel/water separator, with two outbound lines running to my '58 Rudes. The tanks will not burn evenly but the only thing that you need to do to be able to use remaining fuel in one tank, is to wrap something around the fuel line to the empty tank and clamp it off with some vice grips.

I do not recommend this, however, because eventually you will damage the fuel lines if you keep clamping them. I also agree very much with the idea that it is best to run off of one tank so that you will always be able to get back to the dock.

 

[CATransplant]

Re: can 2 6 gal tanks be tied together or 'tee-d'

One other thing about running two tanks from a single line. If, and that's a big if, you can connect the two tanks with a line connected to points near the bottoms of the tanks, they will remain even as the fuel is used.

However, installing such a fitting in the typical plastic fuel tank is probably not a good idea. I don't know of a fitting that would guarantee a seal, and a leak is not a desirable thing.

However, if you had two brand new metal tanks, it would be fairly easy to braze a connector on each near the bottom and connect them with a hose. The risk would be that the hose might get damaged and leak at some point.

It's not something I'd do, since it's so easy to simply disconnect the normal hose from one tank and plug it onto the other tank. For 36 pounds of weight, it hardly seems worthwhile to do anything else.

 

[tashasdaddy]

Re: can 2 6 gal tanks be tied together or 'tee-d'

if you will notice on tanks in boats have top connections, the risk of a lower failure is devastating.

 

[jay_merrill]

Re: can 2 6 gal tanks be tied together or 'tee-d'

I think TD is right. For the cost of a brass valve and some fuel hose, which isn't really all that much, you can deal with the fuel balancing issue much more easily and much more safely. I would also offer the thought that a system with tank nipples mounted in a low position might get the attention of a Coast Guardsman, or other marine official, during an inspection.

I have a four-way on my boat, which gives me the off position, port tank, starboard tank and aux tank(s). The aux line runs under the dash/windshield to the foredeck, and has a quick disconnect on it so I can use one or more aux tanks. The valve is mounted on the starboard side, just behind the steering position, so switching tanks is easy and safe.

While each boat/layout/need is a bit different, I recommend going to a valved scenario that is approximately as I have just described.