Oldsmobile/Buick Repair: fuel gauge, fuel level sensor, fuel gauge

Question
I have 2002 Buick Century custom, the car has approximatlly 62,000 miles the gas guage has started to read iradically it will read full then go to empty and back to full. it has stayed on full. I would like to know what are some things to check that may cause this to happen the fuses check out ok. Also I have computer code P0306 cylinder 6 miss fire, I have replaced the plugs and plug wires and still get the code what else could cause the code and could the two problems be related? and help will be greatly appreciated

Answer
Hi
I REALLY doubt the problems are related, although your dealing with a man made machine...anything is possible.
That being said, the Fuel gauge is PROBABALLY the fuel level sensor, located inside the fuel tank. This can be accessed from the trunk, but you need a special tool to remove the locking tank unit locking device.
The #6 misfire could be anything. Injector. Weak ignition coil, ignition module, then also ANYTHING mechanical.... cam lobe worn, low compression on that cylinder, sticky valve.
I would recommend having the misfire diagnosed properly, as you could spend LOADS of money on just replacing parts.
I Hope this helps
Pawl