Join Date: Mar 2002
Location: Austin, TX, USA
Re: Gas Gauge Needle Calibration
I second using a substitute resistance at the sender end. It will give you a good idea if you have an electrical problem, gauge problem, or a sender problem. For example, grounding the sender lead should make your gauge read E (or below). If the gauge needle was sticking, this test would reveal it.
Also, it might be a good idea to rig up a test lead so you can measure the senders resistance when it's full / empty to see if it's in the ballpark. If you decide to drop the tank and twiddle the sender instead, just beware that the range of motion is a bit different in the tank than out. Unfortunately fuel gauges aren't precision instruments, but it sounds like yours is way off in a bad way.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI