Probably a bad ground, worn out resistor or damaged float that as filled with fuel and no longer floats in gasoline.
My 1988 ford thunderbird has a digital gas guage. Last week it stopped working. Now all it reads is E (empty) How can I fix it?
More then likely you need to replace the Thermostat.
check the wiering /our your sending unit no good
FIRST YOU MUST DETERMINE IF IT'S THE FUEL GAUGE ON INSTRUNENT PANEL OR THE FLOAT IN THE THE GAS TANK.YOU CAN CHECK THE INSTRUMENT PANEL GAUGE BY TAKING A JUMPER WIRE TO GROUND WITH THE IGNITION ON.TO CHECK THE FLOAT YOU'LL HAVE TO DROP GAS TANK
bad ground or float stuck 2 possibilities i can think of
What engine do you have?
10w30
check your conectors or the float might have a hole in it
in the gas tank
you will have to have this evac by a a/c tech.
Not to be disrespectful, however you just answered your own question...if it's a V-6, there are 6 spark plugs!
Get under the car