Fuel Gauge/Fuel Sending Unit

[user543457]

My fuel gauge won’t go full scale, it stops at ¾ full. I pulled the wires off the sending unit and shorted them together and the gauge went all the way to full but the sending unit will not send it all the way. I tried a new sending unit but it does the same thing, only ¾ full. Is the gauge adjustable, i.e. can it be zeroed? Am I missing anything?

[boats.net]

Most can be adjusted in the tank, you either have it installed improperly or there is something in the tank keeping the unit from extending all the way up.

[user543457]

Originally posted by boats.net View Post

Most can be adjusted in the tank, you either have it installed improperly or there is something in the tank keeping the unit from extending all the way up.

I tested it outside the tank. The sending unit is a "Reed Type", 240-33 ohm. The gauge will go to empty but not to full. It also did the same with the old "Swing-arm Type" sending unit.

[boats.net]

Remove the sender, and manually bring sender to full (while still connected) check the guage, if full then problem is in tank if not problem is either wiring or sender.