Gas Gauge Issue on Suburban

[jep5555]

My 99 Sub has an erratic gas gauge. It will register accurately and then jump all the way to empty and back to normal. At other times, it jumps all the way to full and drops back to empty. At other times, it will read noramlly for a few days and then jump up from say 1/4 tank to over 1/2. Any ideas what is going on? Is this a defective sending unit? How can I diagnose and fix it? Thanks for any help!

[RockinWRX]

The guage reads off of a variable resistance "swing arm" in the tank itself. The whole in tank thing is one unit with the fuel pump inside of it , although the fuel pump can be removed. Its possible that some of the resistance contacts may be dirty or out of position. The entire unit may be more than $250 , depending on if it was redesigned recently. Fuel guage reading problems on GM's are common , its the design of the sending unit , its rather fragile.

[Flatrater]

Actually the sending unit uses the fuel to lubricate the sender. When the tank is run low the sender gets worn out. Usually you can replace just the sender on most GM cars and trucks. Also for FYI the sender sends a signal to a computer which buffers the needle movement so that it does not move all the time when you are moving like they use to move!

[kriek]

Previous comment: "Usually you can replace just the sender on most GM cars and trucks" Can one of you give me an overview description of how I might go about replacing the sender? I assume you need to drop the gas tank and get inside somehow. How involved is dropping the tank and how easy is it to get at the sender?

Should have mentioned, I have a '00 Suburban

Thanks, Ken

[aeby]

99 burb same issue with hum. changed fuel pump with delphi oem, no help. believe it is the fuel pressure regulator. when changing, do i need to remove upper and lower intake plenum to access fuel rail and regulator? do i need to drain coolant? thanks.