'81 K5 fuel gauge wiring problem...
 

I have a 81 k5. The fuel gauge is not working. The sending unit is OK (pulled tank - checked sending unit w/ ohlm meter - all good). The gauge itself works. i have the cluster off and jumped over and the indicator moves to full. So what am I missing? there are 3 wires at the gauge: black (ground), Pink (sending wire), Pink/Black (???) that one goes behind the fuse box. i have not pulled the fuse box but think that is where I am headed. When I jump from a different cluster wire that gets power when the key is on to the Pink/Black wire the needle moves to full. Which wire supplies power to the fuel gauge?

i know that pink wire that goes into the fuse box is the one to the sending unit. check under your hood and look at the bottom of the fuse box you should see that pink wire running down under the truck to the back of the tank. trace it and inspect it to see if its broken somewhere

Got it!! Pink Black disconnect behind fuse box. we have a fuel gauge!

ok so i have a similar issue my 85 blazer didnt have the wire running from the tank to the sender so i connected it from the tank and ran it up to the back of the cluster i read somewhere that #18 on the connector(that goes to the cluster) is the fuel guage i tried connecting it there it moved but doesnt seem to work. Also there is 2 wires on the #18 pink wires. Hope you can help