After responding to a "Fuel Gauge Drops to Empty" post earlier, I decided to take a look at my old sender that hasn't been tossed yet. My assumption was that years of moisture had rusted the sender. Turns out that despite my generally rusted out sender, that was not exactly the root cause. I found that the resistor winding wire had broken. In my case, on the 6th winding or so. It appears that it works to show full because it contacts the actual wire terminal, then drops to over 3/4 tank because it is contacting the broken wire, then drops to empty as soon as it loses contact with the broken wire, since the circuit is now open. The rest of the swipe path, while worn, actually looks fine, and the arm still contacts it.
Theoretically, you could solder that wire back in place, but it is tiny and you will probably have to solder it to it's neighbors. That alone would just leave you at full a while longer, but if the solder adds extra resistance then you would read lower below the solder joint. By the time you pull the seats and crack open the tank, may as well just replace the sender for ~$100.
I think this should fix it....
Jason
Theoretically, you could solder that wire back in place, but it is tiny and you will probably have to solder it to it's neighbors. That alone would just leave you at full a while longer, but if the solder adds extra resistance then you would read lower below the solder joint. By the time you pull the seats and crack open the tank, may as well just replace the sender for ~$100.
I think this should fix it....
Jason