Originally Posted by phunk

That is a large amount to lose. So the sensors are wired in series, out one into the other and out again to the gauge. If either of them had a broken wire or crimp that came out, the gauge would entirely die.

Ive attached a page from the service manual for determining which sensor is bad. If you fill the tank again, without having to open the tank at all, you can just unplug the tophat on both sides of the tank and test resistance across the sensor terminals. Both should read about 3.0ohm full... whichever one is way out, is your culprit. I will bet its the passenger side, since its been handled more.

Also, dont open the tank until you think its more than halfway empty, or it will make a big mess.