There isn't a single ohm reading for a 2003 Chevy S10 fuel level sending unit. The resistance changes as the fuel level changes. A full tank will show a low resistance (near 0 ohms), and an empty tank will show a high resistance (often around 240 ohms, but this can vary slightly depending on the specific sending unit and gauge). The resistance changes gradually and linearly between those two extremes as the fuel level changes.
You won't find a specific "correct" ohm reading; you need to test it across the full range of motion to see if it's functioning correctly. A wiring diagram or a repair manual specific to your vehicle's year and model would show the expected resistance range and how to test it properly.
