fuel gauge not working

[LSUTIGER1947]

I'm lookin' for help. My gas gauge quit working on my 03' 210. I replaced the gauge and sending unit( they came as package so I know they are compatable) but still no luck. I ran a direct wire from the sender connection on the back of the gauge to the sending unit, still nuthin'. I'm stumped. I sure could use some help from one of ya'll out there! Thanks and go Tigers!

[Mud Runner]

Your guage is wired so that it gets voltage from the bus behind the dash. Basically, there is usually a purple wire that feeds all the dash guages. The 12 volts goes through the guage and out to the sender. The sender has a variable resistor that varies according to the level of fuel in the tank. The circuit is completed by the sender being grounded either directly to the tank or a separate ground wire. You can take the wire that goes to the sender off and hook up an ohmmeter to it and ground to see if you have the sender grounded. You should read some resistance of up to a few hundred ohms if there is fuel in the tank. If you don't then look for a bad ground. Hope this helps. Here is a generic code for marine wiring. It's old and now the ground wire is coded yellow. I don't know what year it changed. Good luck

FUNCTION -WIRE COLOR(S)

Ground circuit - Black ( Now Yellow)

Positive circuit - Red

Switched positive - Purple

Fused positive - Orange

Tachometer sender - Gray

Fuel gauge sender - Pink

Oil warning sender - Varies with engine manufacturer

Temperature sender - Tan (also horn hot lead)

Trim gauge sender - White w/tan stripe

Instrument lights - Dark blue

Bow and stern lights - Dark gray w/white stripe

Bilge pump - Brown

Engine kill circuit - Black w/yellow stripe

Neutral start circuit - Yellow w/red stripe

Power trim main circuit - Red w/blue or white stripe (Mercury; purple)

Power trim (down) - Light green w/white stripe

Power trim (up) - Light blue w/white stripe

Hull bonding ground - Dark green

Bilge blower - Yellow ( This one definitely had to change but I
don't have the new color)

[LSUTIGER1947]

Thanks Mudrunner! I discovered that the ground wire at the battery had come loose. Your tip saved me considerably more grief. Thanks again and geaux Tigers!