I also have a 1998 Ultra with the fuel gauge problem exactly as you stated. There was no sender fault on my car. It turned out to be an electrical glitch due to low voltage. I took the front cover off the cluster and used my finger to flick the gauge back. It worked fine for the next week. I then had a problem starting the motor and ran the battery down and sure enough the needles flick like crazy! And yes, one of the flicks actually drove the needle "below empty" right before my eyes. I charged the battery and removed the cluster bezel and flicked the needle back into place and it works beautifully.
I can't believe this info is not yet out there on the net as a common problem with these cars!
Sunday, February 20th, 2011 AT 12:32 AM