fuel sending unit help-81 K20

**bart6180** · 05-29-2007, 02:41 PM

i have an 81 k-20 the previous owner decided he was going to try re wiring the ruck and didn't get to far, the problem i'm having is some of the wires he did cut are for the fuel sending unit. so at the tank i have about 6 inches of a purple wire coming off and a little nub where anothe wire plugged on, wher are the othe ends of the wires supposed to go, which is ground???

**TrailLeadr** · 05-29-2007, 04:49 PM

Originally Posted by bart6180

i have an 81 k-20 the previous owner decided he was going to try re wiring the ruck and didn't get to far, the problem i'm having is some of the wires he did cut are for the fuel sending unit. so at the tank i have about 6 inches of a purple wire coming off and a little nub where anothe wire plugged on, wher are the othe ends of the wires supposed to go, which is ground???

Holy smokes, are you serious?!

Well that sounds like fun

I'll see if I can get a schematic up later this evening, however someone may beat me to it <cough...unplugged....cough>

**unplugged** · 05-29-2007, 07:38 PM

The wiring diagram from Autozone doesn't give specific detail of the fuel sender circuit. It shows a tan/white wire going to the instrument panel connector which leads me to believe that is the 'hot' connection and the other wire you mentioned is perhaps the 'ground.'

**unplugged** · 05-29-2007, 07:50 PM

This might help too: From CarJunky.com

If he unplugs the fuel tank sender the gauge will (Or should) go to the full mark (high resistance) but if he would ground out the purple wire at the sender the gauge should go to the empty mark.
This is with the ignition in the run position.
A word of caution though if you are going to try and ground the purple wire, do it only long enough for the gauge to reach empty. It should only take a couple of seconds to get there any longer you could cause damage to the cluster due to the high current flow.
Dan.
Below is taken from a GM service manual.
Gauge Description
Fuel Gauge
The fuel gauge is an electrical instrument that measures an electrical current from a variable resistor in the fuel tank. A float controls the variable resistance.

When the fuel tank is full, the resistance is high. Then, the fuel gauge moves to the maximum position (Full) on the gauge face. For diagnostic information, refer to Instrument Cluster System Check .

Fuel Gauge Sender
The fuel gauge sender attaches to the top of the fuel tank. A cam lock ring retains the sender. The tank and the sender uses a seal between them.

The sender has two or three pipes attached to hoses. One pipe is for the fuel feed line. The second pipe connects to the vapor canister. The third pipe is a fuel return line to the fuel tank.

Some senders use a short pigtail connector lead. On other senders, the connector attaches directly to the sender. For diagnostic information, refer to Instrument Cluster System Check

**TrailLeadr** · 05-29-2007, 08:51 PM

I keep forgetting you can get those from Autozone....LOL I'm used to AZ's website being kind of user unfriendly. I rarely go there for support info. I should probably make a habit of it now. I know they've had stuff up there for a while now, but I trained myself to not bother way back when...

**Steve** · 11-25-2008, 04:49 PM

bumping this popular thread.

**Steve** · 03-19-2009, 05:27 PM

Again, bumping this popular thread. It's gotten over 11,000 views, no additional comments?

**Steve** · 05-17-2009, 11:54 AM

A lot of people are searching this thread, it's now one of the 10 most viewed threads on the entire site.

Anyone havethis any insight into this topic, did you find it helpful?