I'm certain it has been a million times, even though I'm new here. I have a 68 coupe. Was an I6 car, has a 350 now. My fuel gauge is on drugs. I put a new AAW full harness in it, but admittedly had to jerry-rig the fuel gauge wiring at the sender (K, I'm lazy...I didnt want to drop the tank).
On my gauge, the "E" is at the upper left of the gauge, say 10 o'clock, and the "F" is over at about 2 o'clock. My needle only ever reads between 3 and 5 o'clock, regardless of how much gas is in the tank. I suspected a bad ground and found what I believe is the ground wire along the front edge of the tank. It was going to what looked like a very bad ground, into a goopy mess of undercoating. I snipped it off, spliced into it and attached it to a good, solid ground between a tailpipe hanger bracket and the rear framerail. Still reads at about 4 o'clock. Any ideas?

 

Hi Dan,

First, is this gauge the factory gauge or an aftermarket gauge, like Autometer or Autogage?

If it is an aftermarket, it should be for 0-90 ohms.

To check it correctly, you'll need to get to the sending unit and pull that out and check things with a multimeter. At full you should see 0 ohms and empty should be 90 ohms and of course, half full should be 45 ohms.

Make sure where you spliced things, there are no "pigtails" from the wires exposed and touching metal. This can give you a false reading also check to make sure it's grounded properly.

Good luck.

Bruce

 

Bruce,
Thanks a bunch for the reply. I figured it was something along those lines. It is the factory gauge, and as far as I know the factory sending unit too. So I will have to drop the tank
If my ohm readings dont line up with the figures you gave me, then the sender is bad? Thanks!

 

How to diagnose the gas gauge and sending unit: Troubleshoot Fuel Gauge

 

sending unit.

not terribly difficult to change.