I'd stick it in there with something. Have you checked to see if it's dead or not? It doesn't care about fuel in the tube, it is a thermistor. Voltage warms it up, and if there is fuel around it, it stays cool enough to not turn on the light. As the fuel level drops, more of it is exposed, and the low fuel light will barely glow. The warmer it gets, the brighter the light will get until it is at full brightness. Make sense?
The old fuel level sensors were nothing but an off on switch which drove you crazy. Many people unhooked them.