Bad fuel gauge or bad sensing unit?

[targatuesday]

Out for a drive this morning and reserve light starts flashing on the fuel gauge with the needle reading 1/2 full. I'm in some twisty mountain roads and don't think much about it... just fuel sloshing I assume. But when I get back to the level roads the gauge continues to read 1/2 full and the reserve light on. At this point I know I am at least 30-40 minutes from the nearest fuel station and start to worry a bit. Then it happens fuel gauge needle flickers from half to empty, back to half again. I start driving very gingerly using "one-toe" throttle inputs and manage to make it to the gas station. Fuel gauge is still reading 1/2 full when the car drinks 15.3 Gallons!

Based on this scenario does anyone know if the culprit is the sending unit or the gauge? Does the same float inside the sending unit trigger the gauge needle and the reserve light or is there a separate trigger for the reserve light?

Thanks in advance for any and all responses.

[RSTarga]

I tend to rely on my odometer more than the fuel gauge. I've replaced the sending unit several times, I am beginning to think todays fuel somehow corrodes the sending units. I think the reserve light is more dependable than the level for some reason or other.

[targatuesday]

I read every thread I could find about this problem today and it seems more common than I would have imagined. Doesn’t seem to be one fault or solution. For some it was sending unit, for others the gauge, and some wiring and connections. I guess I’ll dig in and start diagnosing and testing.

[Scott A]

Maybe before you spend $. Clean all the associated connections. And nearby grounds.

But in reality. The wires inside the sending unit are tiny tiny. And don't have a chance against rust.

I took my sender apart and repaired it. So it is possible.

[gled49]

I vote for sending unit.

[edmayo]

Just take out the sender, plug the harness on, turn sender upside down, read gauge, turn sender right side up, read gauge again.