Vibrating Fuel Gauge - WTF?

Two days ago the fuel gauge on my 99 OBS Tahoe started vibrating with the key on. I mean oscillating back and forth about 10% of the range at a rate
similar to or faster than an A/C motor. I thought my vision was blurred at first...but the other gauges are steady.
I thought at first it might be picking up interference from the pump, but it even does it with the key on and the engine off....i.e. pump not running.
Is there an obvious cause here? Is the truck about to be sucked into outer space by a UFO.
Can I fix it affordably? or do I just live with it?
Thanks in advance.
Skimmer
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Hi!

I would start by looking for bad connections, especially anything to do with grounding. It's also possible that the sending unit in the tank is bad. I've got a '94 C1500 whose fuel gauge went completely bonkers one day (it was reading beyond the scale and moving all over the place like crazy with the truck sitting still and the key on). Replacing the sender fixed it.

Only if you hear a lot of vacuuming sounds or see strange lights.

If it's a wiring problem, you only spend your time (and maybe temper, if it's hard to find) on it. Sometimes the sender is part of the fuel pump, so you may have to get one of those and that will cost some money. But the real fun is dropping the tank, which you'll probably have to do since you have a Tahoe. I undid all the bed bolts on the truck and lifted the bed right off with a tractor. From there I could straddle a frame rail and work on the problem easily. I don't think the body would come off of a Tahoe so easily.
William
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