Fuel selector valve

I am new guy to this group. I have a 1978 k10 that I am doing a full restoration on. I have ran into a problem i cant figure out how to wire the fuel selector valve. My truck was originally a single tank and I am trying to make it a dual tank. The first picture is the valve i bought from my local NAPA and the second picture is the plug i pulled out of a truck that had two tanks, that went to the inside of the cab. I need some help on how to wire the selector into that plug and which wires go to the fuel sending units. Thank you for the help.

Moved to get more attention. You can post up some truck pics and tell us about your truck in the introduction section. @chengny @gmachinz @RetroC10Sport can help with the wiring question

Good Job Grasshoppa, you gettin' it @animal.

Welcome aboard Chase. So are you just needing a wiring diagram and can handle it from there or needing more descriptive help? We never know a person's mechanical ability but we can get whatever help you need. @chengny is the go to guy for a wiring diagram on the 3 port valve on the older squares. The newer squares used a 6 port valve for the Evap Canister Emissions.

Welcome to the site.

Yes I need I wiring diagram. If I use the six port one do I have to have the canisters? My local NAPA said they could not find a three port one.

You have the wrong valve for the wiring you're attempting to use.
If you have a feed only, no return line, fuel system then get the Standard Motor Products FV1 valve.

If you have a fuel return line you need the 81-91 Pollack motorized valve you have. I'd try to find the wiring out of a 1981-1986 CK or a 1987-1991 RV diesel squarebody...
Use the 87-91 dash switch. The 81-86 dash switch is a problem child.

If you're familiar with installing Packard 56 and Weatherpack terminals and insertion/extraction in these families of connectors you can probably roll your own harness.
The Pak-Con fuse panel connector and 87-91 switch connector shells are only available used but the terminals are easily available.

My mostly complete NL2 Dual tank switching theory of operation is here. #2 is the 73-80 system. #3 is the 81-91 system.
http://www.gmsquarebody.com/threads/1973-86-ck-1987-1991-rv-nl2-dual-tank-theory-of-operation.21341/

Wiring diagrams and service manuals are in the Reference Library forum.

Ok so I think I am going to switch the valve I have in it out with the other ac delco 467513 one. The one I should have got. But i will still need a wiring diagram for that one. I do Have a return line.

Toggle switches are easier to install and more reliable than the stock rocker switches.
You can drill a 1/2" hole to use a polarity reversing toggle switch.... Like this one.
https://www.amazon.com/Position-Reverse-Polarity-Control-Maintained/dp/B001PNHBW6

The above polarity reversing switch is 30A @ 12VDC maintained with centre off. Meaning it's ON-OFF-ON and it stays in all three positions.

The GM 81-91 fuel selector rocker switch uses a different connector shell than the above toggle. However, the toggle switch can use the same connector as the earlier 1973-1980 GM rocker switch...

On closer examination, you'll find the wires on both the early and later harness are terminated Female Packard 56 terminals. It's just the shell that's different. You can still buy the Packard 8911352 shell from Mouser Electronics among other distributors.

Swapping the 73-80 Packard 8911352 plug onto the 81-86 switch wires is a fairly easy R&R.

So is this the one I need? which is the acdelco 467513

miller78square said:

Ok so I think I am going to switch the valve I have in it out with the other ac delco 467513 one. The one I should have got. But i will still need a wiring diagram for that one. I do Have a return line.

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AC Delco 467513 has been obsolete for many years. There are ZERO aftermarket direct equivalents.
You'll get severe sticker shock when you see the price on auctions for that part.

Install or build the later harness and use the 6 port motorized Pollack valve you already have. You can buy that over the counter.

So replace this switch the one that is close the the cigarette tray with the switch you linked?

Ok so i can keep the valve i have? Do you have a diagram on how to make the wiring harness for the pollack valve?

This is the connector that i bought with that pollack valve.

miller78square said:

So replace this switch the one that is close the the cigarette tray with the switch you linked?

You must be registered for see images attach

Click to expand...

I thought you had a single tank truck... If you already have that switch mounted in the dash you have a square hole. Unless you want to weld up the hole and drill a 1/2" hole I'd use the 87-91 AC Delco D7089C rocker switch. You may have to open up the hole with a file and re-paint the exposed edge but it can be made to fit and look just fine.

miller78square said:

Ok so i can keep the valve i have? Do you have a diagram on how to make the wiring harness for the pollack valve?

Click to expand...

Since you have a glass fuse 77 you're going to need a mild hybrid of the 70's & 80's system.

What's your skill level with vehicle wiring?
Do you have the tooling and the knowhow to terminate new wires for that Weatherpak plug and maybe Packard 56 terminals as well, extract the existing terminals, and insert your new wiring in them?
Can you read the factory wiring diagrams in my signature? 1973-1991 GM diagrams are available in PDF. I scanned them from my library for the members here and several other boards.

Can you draw up hybrid wiring diagrams you need based on the factory diagrams?

I'm worried about needlessly frustrating you by outstripping your skillset. I've been doing this kind of stuff for more than 40 years so it's bloody easy for me. No so for other folks and I have to be careful that I don't run off at the mouth and frustrate folks.

There is a fellow that custom builds NL2 harnesses for EFI conversions. @gmachinz I see no reason he couldn't build a simple NL2 harness like you need.
I've never used his services as I can and do roll my own...

Yes i do have a single tank truck. So i will do what you said just drill a 1/2 inch hole and put that toggle in. I have a parts truck that has that switch but it did not have any of the wiring for the valve. I am not very good with wiring im only 16 i can do easy stuff like wiring car stereos and subs. I have already replaced the wiring that runs to my tail lights and the harness that runs the motor that wasnt to hard but the wiring diagram that painless sends with their product is easy to understand. Im sorry but what you are saying is confusing to me. Yes i could put different terminals in and put new wires in it. Thank you for the patience and understanding i really appreciate it.