sending unit problem ??

[killswitch]

I believe it's a sending unit issue, but trying to verify before I replace the unit. Here's the issue...................
Fuel gauge reads full with a full tank. (31 gal) As fuel is consumed, the gauge will eventually drop to the 3/4 mark and that is where it stops. When the switch is turned off, gauge returns to E. Switch on, back to the 3/4 mark. Unless I fill the tank again, then it's back to F and the process starts again. The gauge does register correctly between the F and 3/4 mark before it stops at the 3/4. Today I pulled the unit and worked the float manually with the same results as if it were in the tank. Switch off, gauge to E. Switch on, works fine between 3/4 and F. Replaced the connectors and checked the wiring. My guess is with the gauge actually moving with the switch on or off, and working correctly between the 3/4 and F, the problem is the sending unit. Am I thinking correctly or not. Any thoughts and thanks in advance for the input.
Boat is not that old..........2004.

[fishinfool]

You are correct sir, it is a sending unit problem. The sending unit works on a variable resistor. As the float moves up and down it moves a contact across a resistor that is painted on a ceramic plate. if there is a spot worn out or the contacter does not touch in certain areas it will not read correctly. Replace the sending unit.
FF

[Slough]

Take your wire off the sending unit. The gauge ( with the ign. switched on ) should go to full or empty. Ground the wire and the gauge should go all the way the other way.

[killswitch]

Thanks for the info. One more test this weekend should confirm.

[killswitch]

Just installed the new one..................back in business.