To correct a fuel gauge that might be reading incorrectly, you may want to try this before you dig deeply into how to fix that problem. This is from a Youtube video regarding how to troubleshoot and fix an incorrect reading fuel gauge. The YouTube presenter suggests that over the years, the electric components of the fuel sending unit in the gas tank can become corroded from the gas. That can cause the fuel gauge to incorrectly indicate how much gas you have left in your tank. One of our retrobird owners has that problem of his fuel gauge indicating he still has a quarter of a tank of gas left, when he is actually running on empty. One way to counter that, is to keep the tank full of gas most of the time! The other way suggested was to do this below.

If you use Chevron, Texaco or Caltex Gas, it already contains Techron and you probably don't need Techron Concentrate Plus. However, should you occasionally fill up with lower quality gasoline, you may need Techron Concentrate Plus to help clean up deposits that can build up over time. In addition, if you have an engine that is sensitive to deposit formation, or if your vehicle is regularly used under severe conditions, you may also benefit from using Techron Concentrate Plus.

*In as little as 4,500 miles of driving, gasolines with Techron can remove up to 50% of harmful carbon deposits.

Try some Chevron Techron Concentrate Plus in your gas tank to clean the sending unit... at least for two full tank fills. After that, see if the Concentrate has cleaned the contacts and if the gauge is now reading normally.. If this works, it could save you from having expensive repairs to the fuel gauge indicator, or replacing the fuel sending unit in the gas tank... You can obtain this product from many autoparts stores or Walmart, 12oz bottle for about $5.