Dual-fuel tank

[Eugene]

Hi guys, I would just like to ask if there is such thing as one way fuel valve?

We have successfully installed an additional 5 liter fuel tank on my 150 and I tested it for 2 days. What I've observed is the fuel from my under tank flowed up to my upper tank, hence, it over spilled after using it for 2 days.

Any thoughts? Thanks!

[CROSSBOLT]

Maybe we have a translator problem here because I have trouble understanding how fuel can flow from an under tank into an upper tank. I am reading "under" to mean lower and "upper" to mean higher.

Karl

[Eugene]

Hi Karl,

Yes, you are right, under tank means lower tank and upper means the higher tank. Sorry for that.

I'm puzzled too how the fuel flowed up to the higher tank. Last 2 nights ago, I filled both with half tank just to check if there would be problem. Last night when I checked on it, there were overflowed gas in my utility box, when I peeked inside the lower tank, it's almost empty and the higher tank is full.

[CROSSBOLT]

I will bet your lower tank has a non-vented cap or no vent whatsoever.

Karl

[de dee]

I will bet your lower tank has a non-vented cap or no vent whatsoever.

Karl

    and the lower tank has a heat source under it,  close to the engine,

[de dee]

there is a reserve switch on my tractor one tank or the other it is a sears garden tractor pgt 9000  parts are available at sears parts department

[Eugene]

I will bet your lower tank has a non-vented cap or no vent whatsoever.

Karl

HI Karl,

So what you are suggesting is to change my tank cap to a vented one?

We're planning to put a switch so that I can close the vacuum from the fuel pump. I'll be using the higher tank first and when it goes empty, that's the time I'll be switching on the vacuum to trigger the fuel pump.

Any thoughts, guys? 

[Eugene]

there is a reserve switch on my tractor one tank or the other it is a sears garden tractor pgt 9000  parts are available at sears parts department

We don't have Sears parts department here in our place.

[CROSSBOLT]

A vented cap may solve the problem of undesired transfer. I visualize your system as the fuel path from each tank goes to a "T" and then to the vacuum valve and then to the carburetor. The pressure in the auxiliary tank (with no vent to atmosphere) pushes the fuel into the main tank. Am I on track, so far?

You have a great idea to extend the limited range of your scoot. It is also a great idea for several models including the People GTi300 which will go 100 miles with a TINY reserve. It is a great cruiser but with about 2.4 gallons is limiting options for refueling thus requires a red plastic gas can strapped on somewhere. All kinds of specialty shops make aux tanks but it is up to the installer to make it work. You are, so far the pioneer in developing a usable system.

Most aircraft have two or more fuel tanks plus a system of selecting tanks to feed the engine(s). Each tank is vented independently. On, off and crossfeed is a manual function of the pilot. The basis of these systems is simplicity.

Karl

[AMAC1680]

I don't screw around when it comes to gas and spark. I've used these tanks for long haul and love them. Not cheap but gets the job done right.

http://shop.spunaluminumgastanks.com/Motorcycle-Tour-Tanks_c18.htm

AMAC

[Eugene]

A vented cap may solve the problem of undesired transfer. I visualize your system as the fuel path from each tank goes to a "T" and then to the vacuum valve and then to the carburetor. The pressure in the auxiliary tank (with no vent to atmosphere) pushes the fuel into the main tank. Am I on track, so far?

You have a great idea to extend the limited range of your scoot. It is also a great idea for several models including the People GTi300 which will go 100 miles with a TINY reserve. It is a great cruiser but with about 2.4 gallons is limiting options for refueling thus requires a red plastic gas can strapped on somewhere. All kinds of specialty shops make aux tanks but it is up to the installer to make it work. You are, so far the pioneer in developing a usable system.

Most aircraft have two or more fuel tanks plus a system of selecting tanks to feed the engine(s). Each tank is vented independently. On, off and crossfeed is a manual function of the pilot. The basis of these systems is simplicity.

Karl

Hi Karl,

Thank you!

Yes, you are right! The upper and the lower tank meet at a "T". What we did now is we installed an on-off fuel switch but instead of putting it in the fuel hose, we installed it on the vacuum's breather hose. In that way, the fuel pump's vacuum won't be working if the breather is shut. I'll be testing the system for a long ride the day after tomorrow. I'll be having them full tank and we'll see how it goes. I'll be sharing some pics later for others to visually understand what we're talking about, Karl.

I haven't found any vented fuel cap as of the moment.

Thank you for your time!

[CROSSBOLT]

Super 8 150 Owner's Manual shows fuel cap under the seat so the "high" mounted tank will be gravity feed to the carburetor, therefore, no fuel pump. I say this because I did not understand what you said.

Karl

[Eugene]

Super 8 150 Owner's Manual shows fuel cap under the seat so the "high" mounted tank will be gravity feed to the carburetor, therefore, no fuel pump. I say this because I did not understand what you said.

Karl

That's right. Sorry for my crooked grammar.

[CROSSBOLT]

No need to apologize for "crooked grammar" since many of us cannot understand each other! It is a process of question and answer to establish clarity. I would post a diagram if I were smart like some of these others.

Karl

[Eugene]

Hi guys, I've tested the functionality of our dual-tank project on a long distance drive and I can say that it was a success!

Here are some pics of the system we've made:


This is where we put the gas tank.


This is the fuel switch we installed


This is what it looks like inside my utility box


This is the "T" connection which links the two gas tank