86 crown vic gas gauge problem
 

so i just bought this 86 crown vic 4door sedan from a local car lot. and the gas gauge doesnot work at first i thought it was the fuel sending unit which i found out is built onto the fuel pump assembly. but the thing is the gauge doesnt work at all. it stays on empty and no fuel light comes on. its actually fallen below empty. so im wondering i know these car have an anti slosh control on them or something like that and i was going to start there first and check if its that. i have to get this fixed cus im going to be heading to TN soon and it would be nice not to guess :P on my fuel lol. anyway any great help would be appricated. ive been searching google for 3-4hrs and have called a half of dozen parts stores. anyone eles ever have this problem and can maybe give me some advice where to start