When I refurbished my Mini's fuel tank, I decided it was the perfect time to install a new sender unit, as the old one was nearly 40 years old. It was one of those "might as well" things.
It turns out the new sender unit is not any better friends with my Mini's fuel gauge than the old one was. They both sort of worked, but neither one really showed Full or Empty correctly and I basically ignored them and just filled up the tank about every other time I drove the car to ensure it always had fuel.
But with a refurbished fuel tank and a new sender unit, I wanted to fix the problem. So I decided to install an item called MeterMatch which is designed to make your fuel gauge completely accurate. Basically, it's a little computer that goes in line in the wiring from the sender to the fuel gauge. It receives whatever the sender unit is sending, and then translates that information into what the fuel gauge is expecting to receive to display correctly. I think this product is normally designed to be positioned hidden in the dash somewhere close to the fuel gauge. But I decided to install mine in the boot closer to the sender unit. (more room to work there).
I have not yet completed the installation. I drained the fuel tank to get the correct calibration for Empty on the gauge. Tomorrow, I plan to fill up the tank and calibrate the Full setting. The MeterMatch unit is designed interpolate readings between the two extremes to display 3/4, 1/2 and 1/4 on the gauge. So we'll see how that works. There are also ways to fine tune the unit to be more accurate for the readings between an empty tank and a full tank - apparently this is very useful if you have an odd shaped fuel tank that doesn't empty in a linear fashion.
So we'll see how that goes. I was reading the instructions and also learned that this unit can be used for a temperature gauge in much the same manner as a fuel gauge. Interesting.
(The circuit board sits in a little black plastic case, but it comes out of that during the calibration process).
I've always bent the float arm to register 0 accurately but gave no mind to full. I'm curious what variables in ohms that board gives you for the different settings.