..have a mechanic check the fuel level sending unit ..it's just a plunger that floats inside the fuel tank , sometimes teh sensors go bad. someone saying use fuel injector cleaner to fix your gauge is wrong, fyi. it cleans deposits inside the fuel injectors and system itself. The fuel gauge is either a bad cluster, or bad fuel tank sending unit, lol
join up at http://www.taurusclub.com/forum/index.php?act=home and they can shed more light on this problem
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2000 Impala - K&N , Magnaflow Cat / resonator , Triple treds ,
SLP "LSX" grille . soon: magnaflow mufflers / tips