Gas gauge problem
 

When I bought my 2002 Silverado, every time I start it up, the "LOW FUEL LEVEL" LIGHT comes on and the gas gauge is on empty, even though the tank is full. It stays that way for a few minutes, and then it begins going up to its normal level, but it takes a long time.

Any suggestions ???

Sending unit in the tank - very common.

gas gauge
 

Can I buy just the sending unit, or do I need to buy the whole pump. How much ??

You can just get the sending unit. If the pump has alot of miles then you could replace the whole unit, Im sure you know that. I look for those parts on ebay. You could also get a new pump for bout $50 and replace both for less than half the price it would cost for the whole unit, just a thought.

New Fuel Level Sensor (Sending Unit) | eBay