Empty - Arm Down = 240 Ohms The fuel sender, for the typical US standard used in a marine application, is a simple device that presents a resistance reading to the gauge with which it is paired. For US fuel gauges, from the
The old float senders were pretty simple and reliable.
They are nothing that is like the fuel gauge on your car.
The best information comes from your fuel logs. You know how much yo put into the tank, you know how many hours you ran the engine. You should be able to calculate your fuel consumption and know, based upon the hours running when you should refill. This logging of fuel consumption has been a staple of boat masters for centuries. Add to the calculations, a regular look at the tank for visual confirmation of available fuel.
The fuel gauge is just an idiot light to indicate you need to check the tank.
When I replaced my sender it was not registering the proper resistance.
I replaced it with one like this.
Be sure to select the correct size to fit the depth of your tank and the correct number of fastening screws.
Check and replace the sender if faulty. If defective I would recommend replacing with the rod type and not the float-arm type. I have found the float arm types to be very unreliable. Also check the gauge for proper readings. The problem could be either the sender or the gauge.