Fuel Gauge not working

[perurider]

My XS' fuel gauge is not working, tach and all lights are, where do I start?? thanks.

[81xsproject]

Check/clean the connection to the fuel sending unit under the tank. While you have that connector seperated, use a voltmeter and check resistance across the wires of the voltmeter. I don't know the numbers off hand, but the Clymers probably does. If all that checks out, pull the headlight out of its housing and check/clean the connections to the gauge and for continuity to the sending unit connector. That's where I'd start.

[petejw]

If you join the 2 wires together that
go to the sender unit under the tank with the ignition on
the guage should move to full, if it does then you can start looking
at the sender unit being at fault, if it doesnt move then youll want
to check the wiring from the sender unit to the guage.

[bikerphil]

I've had the guage itself fail before. I removed it from the tach housing and soldered a thin wire in there that broke. Been good for 15 years. Check everything leading up to the guage first, as the tach guage is very difficult to disassemble.

[perurider]

OK I finally got a multi tester, took tach out and touched where the red and green are on back of gauge it reads 4.5, so I am guessing its my fuel gauge itself thats broke, not the sending unit or wiring up to the gauge. Right ?? I know, I know dont need fuel gauge, but it drives me nuts when something doesn't work.

[motoman]

Remove your tank and remove the sending unit. Check and make sure there is NO rust on the variable resistor contact or the float arm contact and that both solder joints for wires is good. After removing, plug it back in and making sure contact points are all good, pivot float in its arc and watch fuel gauge with key on.

[SFerinTEXAS]

Like petejw said

If you join the 2 wires together that
go to the sender unit under the tank with the ignition on
the guage should move to full, if it does then you can start looking
at the sender unit being at fault, if it doesnt move then youll want
to check the wiring from the sender unit to the guage.

The harness wires

[perurider]

Did that still nothing, I think I need a new gauge/tach. I noticed a big dent in the trim rin of the gauge, maybe the PO tried to fix it also. You know , if it dont work, hit it.

[ManagerMike]

Disconnect the tank sender and jumper the chassis side of the connector (short circuit the harness), turn on the ignition and wait about a minute for the guage to respond. It reacts slowly so that fuel slosh does not register on the level indicator. If the guage moves to full with the harness shorted then the trouble is in the tank.
I, myself, have had to recondition the sender with a bath of dilute solution of muriatic acid and water to remove the rust from the variable resistor to restore functionality, emphasis on the word dilute.
BTW my guage works perfectly now.
If the guage does not move from below empty with the jumper installed, then the trouble is in the Tach head or related wiring, and your troubleshooting just got far more complicated. Good luck.

[perurider]

Do you mean take a jumper and put it in the plug that is right under the seat?