Dual Fuel Tank set up

[Imogene]

Hey everyone. I am trying to figure out how my duel fuel tank works. Under the middle seat, near the overdrive, I have a lever that controls the right and left tanks. Does anyone know how these work? Do I move to the right, fill it up, and then move it to the left to fill that tank up?

I just filled up what I thought was just the right tank, but it started to leak through the left after I put in about 10 gallons - might have been through the connectors and not the tank itself.

Are there any diagrams on how these systems work?

Thanks!

[mrmoose]

Mine is not a dual tank setup but if you crawl under your truck then you will see how it all works clear as day.

[siii8873]

all the control lever is on a dual tank setup is a two position valve. in left position it opens the port to left tank and shuts port to right tank and vice-versa. It shouldn't open a path between the tanks. You could have a leaky valve the cork seal on these dries out and you may be leaking from there. But I think you would need to fill the tank right up past top for fuel to get to the valve without pump running. Maybe it could create a syphon condition with a leaky valve and full tank.

[siii8873]

filling the tanks is independent of valve. Not sure your vintage of vehicle but typically the left tank is filled from under the seat and right tank from normal fill cap on side of the vehicle. All valve does is change where the pump is drawing its fuel in operation.

[SafeAirOne]

I just filled up what I thought was just the right tank, but it started to leak through the left after I put in about 10 gallons

What does "it started to leak through the left" mean? The left what? The left tank was leaking? The left side of the valve was leaking? The plumbing to the left tank was leaking?

Either way, like Bob says: If the valve is good, there should never be any cross-flow between the tanks (otherwise, your fuel pump would be sucking air from the empty tank along with a bit of fuel from the non-empty tank, and fuel systems don't like air in the lines, generally).

[cedryck]

The changeover switch also determines the reading on your fuel gauge on the dash, depending on which tank is being used.