I have a 99GT 281hp 4.6L sohc mustang.  118000 miles.  When I took it off my sons hands it was bound for the junkyard.  The fuel gauge didn't work so I did what I do on my bike and used the trip meter.  Took the car in for new paint, put on a bbk cold air intake, new underdrive pulleys, clutch, rebuilt Tremec3650 tranny, flowmaster exhaust, pretty much everything and when  I got it back the fuel gauge worked.  Finally got to installing the fog lights and at the same time put a monster tach in it but DID NOT hook the tach up yet.  Now the gas gauge is not working any more.  I am assuming I need either a new sending unit or the computer needs reprogrammed.  Any info is greatly appreciated.  
Also need a little help with the wiring connections on the new Monster Tach if anyone has info on that.
