Fuel Gauge Problem

Hello everyone, I have read several threads about problems with erratic fuel gauges, but my problem is slightly different. Like the others, the needle on the gauge jumps between full and empty, but unlike any that i've read, the needle stops and begins working normally as soon as the car is put in drive and begins moving. I just wanted to know if anyone thinks the sending unit is still the likely culprit in this situation? or does anyone think something else is the problem since the problem fixes itself once moving? Any help is much appreciated!

Check the grounds.
MT

Thanks for the reply, although I'm not going to be the one to do these repairs, and want to give my mechanic a few more details (he's heard of the problematic fuel gauge but is not entirely sure if there's a fix for the problem without replacing the sending unit). Could you be a little more specific as to which grounds you mean, and I'll ask my mechanic to check them?

Year make and model and 2-4 door engine and transmission?

2001 Chevrolet Blazer LT 4x4, 4 door, 4.3L V6, 4sp auto...sorry for not including that earlier...

Fuel level sensor ground is on rear frame rail.
Look for some black wires grounded to the frame.
Just Tell him what it is doing and do not try to fix it for him.
A good mechainc should be able to take it from there.
Good luck
MT