I just picked up a '76 GMC Sprint last friday, and the fuel gauge doesn't work AT ALL. Immediatly after I got it, I went straight to the gas station. It took just over 22 gallons to fill it and cost me $39.00. I was expecting just a few gallons since it reads full. I drove 3 hours one way to get this thing and didn't want to run out of gas on the way home, or stop to fill up. How should I go about fixing this? A working fuel gauge is a MUST for me as I drive about 600 miles a week, an that hungry big block uses all it can get. Should I find a replacement fuel gauge first? Are replacement gauges even made? Where are the wire connectors that run to the sending unit in the tank? A wiring diagrahm would help greatly, where could I find one? Thanks in advance.

Charles

there should only be 1 wire running to the tank. if theres a connector that is easily accessable then disconnect it, turn the ignition to the on position and note the reading on the fuel gauge. then ground the wire (make sure you have a good ground) the fuel gauge should be reading completly opposite. if it does then you have a problem with the sender unit. if the gauge dosnt move, then youll have to pull the cluster and check for powers and grounds to the gauge. also check the fuel gauge wire(from tank to gauge) for resistance problems, it could have a break somewhere.

I don't have anything to help, but I do have a similar problem with the gas gauge being nonfunctional.

In regards to your post jimmy74 you said to ground the wire going to the sender, which I'll try. Then you touched on making sure that there was power to the gauge itself on the dashboard.

I just had my dash apart and my gauge has three prongs that plug into the dash. Is there anyplace that identifies what those three prongs are. I assume on is power, one might be a ground, and the other the signal wire. But is there a way beyond wire tracing to tell which is which?

yes. useing a volt meter ground 1 lead and touch the other lead to the 3 terminals, one at a time. (with cluster plugged in and key in the on position) one of the 3 terminals will read battery volts(thats the power) then take the volt meter lead off of ground and put it to battery voltage. touch the other volt meter lead to the remaining 2 gauge termials. when the meter reads battery volts, you have found your ground. which leaves the remaining terminal for signal. I'm sorry if this sounds confusing, but its the easiest way i could explain. let me know how it goes, or if you have any other ?s

I understand, just didn't know if you knew offhand which on was which already.

I probably won't tear the dash open again for a few days, but I'll check things out when I do.

Thanks for the info. Appreciate it.

LostKnight

i try to remember some of these things, but theres too many makes and models to remember. i just thank god for mitchell and alldata. i just wish i had access at home

i read this thread yesterday, and i got into my car this morning, and now my gauge in my 77 el camino is messed up too! it was way past full and has stuck there. i'm gong to check it out tonight and hopefully it's just a bad ground or broken wire.. thanks for the info! -Chad

I found what was wrong with my gas gage-- there was a single wire that is on the driver's side,near the rear marker light that was not plugged in-the connector was dirty, i cleaned it and sealed the connection with dielectric grease and the gauge works fine now. thought this might help someone. -Chad

I found what was wrong with my gas gage-- there was a single wire that is on the driver's side,near the rear marker light that was not plugged in-the connector was dirty, i cleaned it and sealed the connection with dielectric grease and the gauge works fine now. thought this might help someone. -Chad
What wire was dirty? I am having the same problem with my 77 and I am not sure what to start with. If you can tell me exactly what wire and what you did maybe it will work, otherwise I am going to replace the gage, if I can fin one, and then the sending unit...Thanks.

The post you are replying to is over 8 yrs old......maybe someone can help you though.....

Crystal; the wire from the front, that plugs into the wire from the tank sender is tan. The connector is not too far from the big plug in the bottom/inside face of the left quarter panel, near the back end of it. The big plug is for the tail & brake lights etc......