fuel gage not working?

[johnjem]

hey guys 12 volt fuel gage and sender been along time what is the best way to diag,the fuel gage ??or sender? the sender is in a tough small place on the top of the tank can just get 1 hand it it/any way does voltage go in and then come out with risistance?

[JackConrad]

    If it is like the gauge on an MC-8 both gauge and sender MUST have a good case to ground connection. Power enter gauge through IGN. or + terminal, then leaves gauge through S or SENDER terminal. It connects to the sender terminal. With a change in fuel level, float arm moves the contact on a variable resistor.
    Problem could be electrical or mechanical. Power to IGN terminal on Gauge?  Removing wire at sender and grounding it should give you a full needle deflection (some gauge will go to F, some to E). If you get the full deflection, problem is usually your sender. Ours was a rust problem. The float arm was all rusted and would not move up and down with a change in fuel level. Could also be a leaky float.
   Jack