Re: My gas guage sending unit is toast!
It doesn't matter whether its a swing arm or tube style. Either type cannot accurately measure fuel level in a tank that is not uniform in shape. Look at it this way -- if a tank is shaped like a pyramid with the point at the top, roughly 1/3 the fuel is in the top half of the tank so when the float says half full, you really have 2/3 of a tank. A square tank obviously is linear, but only if it sits perfectly level in a boat. This of course is a rare event since a boat rarely sits level. Best bet is to replace the sender and calibrate it with the tank empty. You know when the tank is full, so why not set it up so you know when the gauge is accurate when its empty. Tanks with the biggest problem are those that are long, shallow, and rather wide (like mine). Gauge is worthless until nearly empty. Best bet is to install a fuel flow monitor so you know exactly how much fuel has been used.