Ford 1996 Crown Victoria Manual page 65

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.
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