1996 Mercury Grand Marquis Owner's Manual - Page 75

NOTE: At least 2.5 gallons (9.5 liters) of fuel must be added for the fuel gauge to immediately show the new level of fuel. If less than 2.5 gallons (9.5 liters) of fuel is added, the gauge will reach the new level slowly. If the fuel gauge displays only the top two bars and the bottom two bars, or, if fuel remaining or distance to empty functions display CO or CS, then there is a problem. Take your vehicle in for service. When you turn the ignition key to the ON or ACC position, all the display segments will light up, then go off for a second indicating the gauge is working. Then the gauge will show you how much fuel you have in the tank. FUEL REMAIN - Fuel Remaining This function shows you how many gallons (liters) of fuel you have left in the fuel tank. If your fuel level is above 20 gallons (76 liters), the letter "F" (full) will appear on the display. But if your fuel level has dropped to below 1 gallon (4 liters), the letter "E" (empty) will appear in the display. Because of factors like rounding of numbers and fuel movement in the tank, your fuel gauge and the service station fuel pump readings may disagree slightly. 72