Russ Hi. there  4 reasons it won’t it will not work 1st is the float ,mine had a small hole that leaked gas in to it after soldering it twice i gave up and replaced it $5.00 at the ford parts store check that first .. 2nd would be the arm is rusted and will not move that can be fixed also,, a little muriatic acid on the pivot to remove rust build up especially if it sat for a while.and rince with water  you can get a small bottle at any pool store and easy to work with just use cheep rubber gloves it will not hurt your hands if you do not have a cut on them !! you may have to repeat it a few times until it moves easily 3rd the coil is bad,, if it is bad that is a harder fix but can be done clean the coil wire well .than if is broken solder on the back side not where the arm contact is,, just bridging the broken spot ..4th bad ground clean ,clean all ,,,that should be the FIRST thing to do ,,, if you have to replace it ,,,,,the ohm rating will be on the top where it sits on the tank  Dan