Anyone know how to diagnose the fuel gauge/sending unit on one of these? It's electric and I don't know if it's the gauge or the sending unit. Thanks.

On older models of most anything you can check the gauge easily. With key on disconnect wire at sender. Gauge should go completely one way, then ground the wire and should go completely the other way. This also checks your wiring. Hope this helps.

Thanks!! That's a good start.

I've noticed that when the key is on and not running the gauge is steady but when running bounces all over the place. Probably the gauge is bad.

Typically "senders" are a variable resistor...  to ground...    so the power is feeding TO the sender. 

Edited August 30, 20159 yr by flagmanruss