Fuel Gauge Reading Instantaneous Float Movement

[ehjorten]

Okay...so my fuel gauge in my '77 K20 started showing instantaneous float level movement instead of the slow damped movement that it normally does.  Both tanks are reading the proper level, but when the tank starts getting below full the gauge starts sweeping up and down as the fuel sloshes.  Also...if one tank is empty and the other is full, when you switch tanks the gauge sweeps from empty to full IMMEDIATELY!

Since both senders are behaving the same way, both senders are about 2 years old, and the problem presented itself on both tank circuits at once, I am thinking it has to be the gauge that is faulty.  Since the floats do move up and down with fuel sloshing, but the gauge usually moves slowly, there has to be a circuit in the gauge that damps this movement.  I am thinking it is something like a hot-wire ammeter or RC circuit in parallel?

Thoughts?  Suggestions?

Thanks in advance!

[VileZambonie]

Key on, disconnect the wire at the left tank  junction and verify the gauge goes past full. Ground it and verify if it goes full empty. If it works normal swap out the fuel gauge.

[VileZambonie]

also verify the ground connection for the gauge first