Need help! 75' gmc dual tank wiring!

[1975_C25]

Could any of you guys help me out? I'm looking to find a wiring diagram or just some advise would be great, I have an old dual tank pickup, 75' gmc 3/4 ton. The guy I bought it from took the aux tank out along with all the wiring and the actuator. I just ran a line to the remaining tank, but I would like to have a fuel gauge for that one tank. I know where the harness would of plugged in, and have looked in all my local scrap yards and can't find a harness for my pickup. I have the supplies to make my own harness, but besides one wire coming from the sending unit to the plug on the firewall I have no clue what else to do. It has the round plug similar to the tail light plug with 4 prongs in it. Can anyone help with what I need to do??

 

[chengny]

There really is not much involved in that system. You will only need to locate the end of the tan/white wire as indicated in the wiring diagram below. Once you have that, run it to the terminal on the production tank sender (also make sure the sender has a good ground connection). Finally, at the 4 prong plug, connect the tan to the tan/wht. That gives you a sensing leg for the gauge. We will have to assume that the gauge is still hooked up to power and ground through the instrument PC board.

So the gauge will have a hot wire, a reference ground and a variable ground to drive the meter (gauge needle). Here is the schematic with my crappy markups:

Hey wait a minute you're only 15, what do you have a restricted license?

 

[1975_C25]

Thank you very much, I appreciate the help and the diagram, I now see what I need to do. And I live in North Dakota, so I got my lisence at 14 and a half. I turn 16 I'm April so I've had my lisence for over a year now. I got two of these old square body's, and a few 88-98 body styles. I'm a chevy guy! This 75 that I am doing the gas gauge in I built out of nothing. I bought the chassis and body for $100 and I rebuilt a 327 out of a 68 chevy, double hump heads, factory aluminum flat top pistons, slightly over stock cam, edlebrock torker 2 aluminum intake, edlebrock 650 carb, and dropped in a new th350 transmission. I have a total of $230 into the pickup including the initial cost. Did everything myself, traded useless parts I had laying around for other parts to build this, and used what I had laying around that I had collected. I'm a bit of a hoarder when it comes to car/truck parts. Someone offers me free stuff, I get it, part it out, save the parts, and learn how to do stuff like that.

 

[chengny]

Ah that's the life - don't ever get married or it all will come to a screeching halt!