Fuel Sender

[djpeewee]

Anyone have any idea why the factory would install a 15.5" fuel sender in a 17" deep tank? Because of this, my fuel gauge reads dead empty when the tank still has about 20 gallons remaining. I'm thinking of changing it out to a 17" sender so it is accurate. I wonder if there was a reason for the short sender or just what was laying around the factory at the time? I have the 127 gallon Moeller tank. Does anyone else have this problem?

[RobS]

There are two reasons for this:

1) If the tank is "V" shaped at the bottom then the fuel sender is intentionally left short to compensate for the fact that down in the "V" the change in height of the fuel level is not the same change in liquid measure as to the same change in height of fuel level at the widest point (upper portion) of the tank. Is the tank "V" shaped at the bottom? Here's the diagram of the tank geometry I drew when replacing my Centroid capacitance type sending unit so I knew what length to cut the rod down to. I assume you have a capacitance sender, not the float type? This was from my 2000 28TE with a 132 gallon Luther's aluminum tank.

and

2) To keep the sender out of any sludge buildup, if you dare have any!

Reading dead empty when you have 20 gallons left sounds comfortable to me, call it a reserve..

[djpeewee]

The tank is flat on the bottom, but "U" shaped looking down on it, with the opening of the "U" facing aft. The boat is a 2004 flush deck. The sending unit is a WEMA SSL15.5 which is resistive - 240-33 ohms. I would like to know the exact amount of fuel left without the "fudge factor".

[RobS]

Do keep in mind that the fuel pickup tube is an inch or so off of the bottom of the tank

[djpeewee]

Good point. There's no point in being able to measure the fuel all the way to the bottom of the tank if you can't get to it.