crazy fuel gage

I have a 2000 silverado 5.3 that the fuel gage changes the level all the time. It is most active right after fill up. It seems to steady out over a few miles, but at times still will drop to E in a flash, then come back. any ideas what might cause this?
thanks for the help

your sending unit is bad the float is getting stuck

Yep, it's the sending unit. My 2000 does it too. I also have the fuel pump whine that is notorious with these trucks. The guage is a bit aggravating, but I'm not pulling the bed until the pump finally gives up, or until I am Really bored. lol I hear you can change it by dropping the tank, but I beleive it would be easier to pull the bed if you have enough people with you to get it off. That is how the dealer in my area does it.

I did mine in my 99 dropping the tank was alot easier IF your tank is empty it is only a few bolts. Use a floor jack lower it a little disconnrct the fuel lines and wires then drop it all the way down. That way you can clean the tank takes about three hours with a buddy. The bed way you have to remove the bumper, spare tires and all the wires that mount to the bed and alot more buddies that means more BEER!!!!!!!!!!!!

Ok, thanks for the help,
kw

I had the same problem with mine, I talked to the guy at the dealer and he said there's a problem with the ground wire coming off the fuel tank where it attaches to the frame. It's exposed to all of the harsh products that can fly up when you are driving and has a habit of corroding. My fuel guage would sit there and bounce back and forth from empty to full and anywhere in between. I climbed under, removed the ground strap, cleaned it all off, wire brushed where it touches the frame and put everything back together and I haven't had a problem since. That's a quick try fix before getting deeper into Chevys dark problems! Hope that helps!