706G fuel gauge

I have a 706 Gas that the fuel gauge quite working. Would it be the gauge or the unit in the tank? and how to check each one.
Thanks in advance
Matt

Not sure but if its like most older standard gauges temporarily ground out the wire that goes from the gauge to the sender in the tank and if that causes the gauge needle to full deflect THEN THE SENDER IS THE PROBLEM ORRR the wires open from gauge to sender ORRR the tank or sender isnt well grounded. Use a jumper wire to insure the sender has a good ground, some get their ground from the tanks sheet metal and it may not be well grounded, others may have their own ground wire.

If when you ground the senders little terminal where the wire down from gauge is attached the gauge full deflects, the gauge (and its input voltage) and wiring are both okay, so its either the sender is bad or theres a bad ground.

Also insure when the tractor is switched on theres hot batetry voltage getting to the input (NOT to sender) side of the gauge as it cant work unless voltage is applied to its input.

Finally if theres voltage on the gauges input and when you ground the output (just momentarily touch to it dont hold it on a long time) the needle dont move, its a gauge problem.

Often Ive seen gauges where the needle is just mechanically corroded and stuck.

For a gauge to be good there needs to be continuity from its input to output, if it reads an open circuit its bad.

Get it????????? If I missed anything or those gauges are differnt then I described, Im sure the other fine gents can add to this.

John T