Check Engine light / fuel gauge

The fuel level sender (sensor) for the gauge is located in the 'rear of the fuel tank' .. While vehicle is pointed uphill at all - the gauge will register more fuel in the tank than there actully is .. These fuel gauges have a tendency to fluctuate from 1/4 tank to empty while driving on the highway - applying brakes, going uphill or downhill will make a huge difference in the gauge readings .. I own a 2000 S-10 Blazer and I have this same problem, as do all of these vehicles around the mid to late 90's and subsequent year models .. The best thing to do is make sure to keep at least a 1/4 tank of fuel (on level ground) at all times if possible .. That will also help cool the In tank fuel pump and extend it's life. The actual fuel level can be checked with a professional grade scan tool then compared to the fuel gauge to see if readings are accurate... Gauge sweep test can also be performed with same scan tool to test the gauge itself... Then there can be no doubt whether the gauge is correct or not.. Fill up the fuel tank and happy motoring !