Joe;

The 122 fuel gauge system has a very fast response time as it is NOT dampened out to average out readings (as on modern cars (even later Volvos with the infamous Voltage Stabilizers) where you typically have to wait a few minutes after filling the tank for the gauge needle to rise and the full tank to be accurately indicated...or totally electronic cars where you may even need to cycle the ignition for the computer to make a new interrogation of the fuel sender). This causes relatively fast float changes such as fuel sloshing on cornering to be indicated as a bouncing needle.

If your needle bounces consistent with sloshing fuel, no problem, but if your needle bounces even faster, it suggests an intermittent connection possibly caused by poor contact on the float wiper.

I actually use this information...occasionally, when I get really low on fuel, I may give the steering wheel a fast flick from side to side...if I see fuel needle bounce indicating slosh, I know I still have a bit left and I'm OK for the moment, but if there is NO bounce at all, I know I better refuel IMMEDIATELY (no offense intended, but women wouldn't understand, their fuel gauge never drops below 1/2...why is that?). Of course, this effect is also a function of the gauge adjustment, but I actually like mine adjusted like this.

Luckily, I've never gotten stopped for doing this trick in view of a police officer...I'd hate to try to explain my "erratic driving" as a "low fuel level check"...he'd probably have me doing a field sobriety check in about a millisecond.

Hope that helps.