1973-1991 Dual fuel tank systems theory of operation

[MiniD]

Originally Posted by rodstored-72

ok, another question.... how does the tank selector valve work specifically related to the power to it and how does it move to open/close either tank when switched at the dash switch? what turns switch "off" when needed after tank selected. finally how can "a guy" check/verify the selector valve is "switching fully" when activated by the dash switch??

thanks!!

It is a simple solenoid that is not spring driven. It is moved by reversing the polarity of the 12v and ground to the tan and brown wires. This is done at the selector switch in the dash. It slides a manifold back and forth that lines up ports to route the fuel delivery<and return if EFI>.

The there is a switch that is also activated, though I'm not sure how it works in relation to the movement of the solenoid. That switch directs what sending unit is supply a ground to your 12v from the pink fuel gage line.

If you're looking for more information on the valve itself, I'd suggest youtube and visual explanations.