Fuel Gauge Issues
 

Hello. I have a fuel gauge in my 67 coupe that is making me want to throw in the towel. I have the entire int. pulled out to Dynamat the car. The fuel gauge has never worked so I was bound and determined to get it fixed while all of this int. work is going on. I have a after markert guage cluster from Auto Meter the Sport Comp series. The fuel gauge is the correct 3314 model for 0-90Ohms. I dropped the steering column a few inches to pull the cluster out. The fuel gauge is hooked up and lights up fine. It has a red wire to the S terminal and a black to Gnd and a black to the I terminal. The gauge was pegged far right of F...I put power to the S and grounded it and it did nothing...I jumped the S to the I under power and the neddel pegged far left of E....I hooked it back up in the car....turned key to acessories and it pegged far right of F again. Any ideas what this means? All of the wireing behind the dash area is all new and not OEM. Does the wireing that runs through inside of car on driver's side just go back to the tail lights or do the wires in there also go to the fuel sending unit? I would like to try to find the wires comeing from sending unit (W/O dropping the tank) so I can hook the guage up to them and see if it works. Any help is very appreciated. I hate wireing issues! I just know that once my DynaMat shippment is in I will want to put it in and button up the car and starting driving it again so now is my window of opportunity but I am really stuck; did all the stuff I know to do. If any one on here is in the Concord NC area and knows someone I could have look at it that too would be great info. Thanks

The first thing I would do is unplug the connector for the license plate light. It also has the wire for the fuel sending unit in that connector (the tan wire is for the sending unit and the brown wire is for the light). With the harness connected to the cluster, ground the tan wire and see if it goes to the "full" side. If it does go to full, the wire is shorted between the connector you unplugged and the sending unit. You will have to drop the tank and inspect the wiring and or replace the sending unit.

Good luck!

Would this be good information for a 68?

yes it applies to a '68 also

This isn't how GM's work, the resistance in the sending unit goes higher as the fuel level in the tank rises, and lower resistance as the level goes down. Therefore, with the key on, grounding the tan wire (zero resistance as in an empty tank) will peg the gas gauge to empty, and disconnecting the tan wire from the harness will peg the gas gauge to past full.
Coolbeverage, with your gas gauge pegging past full, that tells me you have a broken connection between the tan wire at the sending unit and the gauge, or the sending unit is faulty. Do the disconnect/grounding test with the tan wire at the sending unit first. If that tests out at the gauge like I described above, the sending unit is bad.

Thanks for correcting me on the issue. I've been working on Chryslers to long. lol

Any time on Chryslers is too long isn't it? Lol
How the GM gauge works goes against what one would think is common sense wiring.

Camaro69 I have the same issue with my 67. I disconnected the tan wire and grounded it but the gauge still read past full at 3 o'clock. any suggestions?? Where does the tan wire go to?

I did get this resolved. I had to drop the tank and put a new sending unit in. The tan wire carries the single to the gauge. The only other wire is the ground. there is a place back by tank to frame ground. Once you have the tank dropped it is all very simple just dont get me started on that damn rubber connector between fuel filler neck and tank....I think the devil actually put that piece in there. I could notbeleive how tight it has to be just to keep the gas from spilling out as you even just pour gas in from a can

Glad you got it resolved. Had a busy weekend, you beat me to the answer! ;)