RE: 1999 Deville Gas Guage Always Full
 

Faulty sending unit or bent float rod. Someone may have had it apart before and bent
the float rod when reinstalling unit.

RE: 1999 Deville Gas Guage Always Full
 

First off what is the error code if any. Depending on the code it could be an electical connection other than the sending unit. If it is the sending unit the fuel pump module assemble only cost $247 to $300 dollars and most shop can put it in for $120. Seach around for your repair.

RE: 1999 Deville Gas Guage Always Full
 

Most of the time tarrance it is a sending unit, yet depending if your car has produced error codes to indicate that it is a connecting problem the sending unit is most like the problem.

$89.00 dianostic by the dealer can tell for sure.