Expert: Jeff Grigg - 1/26/2008

Question
Alright, I'm trying to figure out how to fix these 2 fuel gauges for this boat. The gauges are good! The gauges have a light, sensor(sending unit), ground, and an ignition connection on the back. Right now, they're both are wired up from fuel tank to sensor(sending unit) on the back of the gauges. The readings are 9 volts from ground to sensor(sending unit). My question is should it read 12 volts? If so, why isn't? If not, why the gauges are staying on empty when the tanks are actually full? Also, I want to hook it up from battery to fuel tank to gauge but, I think it will short out the gauges because there is no voltage regulator. So will it short out, if I do it that way?

Answer
The pink wire from the sender goes to the S on the gauge.
Black wire goes from ground to the G terminal on the gauge.
Blue wire goes from your light switch to the terminal for the light on the gauge.
A purple wire goes from an accessory switch to the positive terminal on the gauge, you only want the gauge on when either the ignition switch is turned on, or an accessory switch is turned on.
You can test the sender for operation by pulling it out of the tank. Put an ohm meter on the center terminal and on the ground flange. Move the float or arm up and down and watch the meter. If it moves smoothly along with the sender it is probably OK. This does not however test accuracy.
Jeff