Fuel guage /gas tank wiring

[Chevyboy12]

Hey guys I have a 78 k10 fuel guage Pegged way past full got under truck found a green wire off of gas tank disconnected would this wire have anything to do with my problem ?

 

[MrMarty51]

YUP, just might be, hook it up and see whatshedoes.

 

[rscustomrods]

Ok having just went through this, here is what I know:

The green wire is the power wire to the fuel selector vlave, provided you have a dual tank system.

There is a baby blue wire attached to the top of one of the tanks sending units, and a tan one on the other sending unit. Both tanks have their own ground wires. There is another wire that makes the loop all the way around to the firewall and ultimately to the fuel gauge. If you have a short somewhere, your gauge will peg.

Hopefully this is helpful to you.

 

[cj2448]

I have a 77 Chevy k10 want to wire in a new fuel guage but cant track down the fuel sending wire previous owner did a hack job and want to redo it easiest way to wire it up

 

[chengny]

I can't say for sure how it is physically routed - 77's are before my time. If I had to guess, it is probably run alongside the wires that make up the rear lighting harness.

If that wire still exists it will be tan. It originates at the instrument panel plug connector. Heads down to the fuse block area. It enters the firewall at the main harness connector behind the fuse block and emerges on the engine side of the main connector (located under the wiper motor). As noted above, it will then most likely head back to the tank on the inside of the frame rail (either within the rear lighting loom or alongside it).

If the quality of the PO's work is not good, you might consider just running a new lead - at least from the firewall back to the tank.

Find the wire where it comes out of the main connector on the engine side of the FW. There are only 2 tan wires coming through. The fuel tank sensing leg will be in the third row down from the top and either on the far left or right side ( I cant tell which side from the drawing I am looking at). Cut it at a point about a foot or so away from the FW and splice on a brand new length of wire. The connection at the tank end is a special 90 degree push connector. You should try to find one and splice that on the end of your new sensing leg. Otherwise you'll have no good way to attach the lead to the sender head.