dual tank wiring
 

This is what I've got to work with...I have the two green colored wires that run from the selector switch. They are cut about half way down the frame rail but they are there. I do have the tank selector switch still intact inside the truck. This is hooked up with the green colored wires and another wire connected to the fuse panel. Also, I have one pink wire that runs frome the sending unit into the harness/firewall connector. This wire does work as it gives a reading on the one tank that is installed.

How would I hook up the passenger side (the one that is currently missing) tank sending unit so that it reads on the fuel gauge when that tank is selected? How do I hook the drivers side tank (the one I have installed in teh truck) once I need that pink wire for both tanks?

Also, the truck has holley carb so there's no fuel return line, and the vapor canister has been removed so there's no vapor lines either. Would I be better off installing a 3 port valve or a 6 port valve. I assume the 6 port valve was the stock application. I can get one of these (the 6 port) and the plug that goes into it. The plug would be a big help since, like I mentioned above, there's no wiring left anymore!

Thanks for any help you can give me!!:confused:

Re: dual tank wiring
 

It sounds like you have all the necessary components to add an auxiliary tank. You could check the fuel pump and the existing fuel tank to see if they are plumped with a return line. Regardless, I'd 'bably use a 6-port valve. Then, like you said, plugged the three return ports on the valve. I wiring scheme for a stock dual tank setup is as follows:

On the fuel tank selector valve:
Pink/Black = Right Tank Sending Unit.
Pink/White = Left Tank Sending Unit.
Pink = Tank Sending Unit wired to the bulkhead connector going to the Fuel Gauge.
Light Green = Solenoid/PM Valve (Right Selector when switched to +12V)
Dark Green = Solenoid/PM Valve (Left Selector when switched to +12V)

On the fuel tank selector switch:
Pink = Ignition Power wired to Fuse Box
Pink/Black = Ground wired to Bus Bar
Light Green = Right Selector (when switched to +12V)
Dark Green = Left Selector (when switched to +12V)

To help you with the wiring layout, I've thrown together a wiring diagram.

Re: dual tank wiring
 

Wow, that's an awesome description boxrodz.

I am having problems with the dual tank setup on my '86, and was not sure how to go about tracking down the problem. That diagram will help.

Thanks!!!

Re: dual tank wiring
 

my fuel tank switch has one brown wire, one brown with a white stripe, one black, and o e gray. how do I make that work? I'm trying to adapt a dual tank setup into my 1986 K20. also is the 6 port valve and wiring connector the same thing you can get off of LMCTruck?
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Re: dual tank wiring
 

Hey Boxrodz,

What program/software did you use to create that great schematic? I've been wanting to draw several things up using wiring diagrams in the back of some of my shop manuals without defacing the manuals themselves...

All I have is Visio & it can't do it (or else I'm just too stupid).

Thanks!