It could be a bad sending unit. Also it could be getting a bad connection so make sure you check them. Also the gauge itself might be bad but I dont think thats the case. Thats my 2 cents on the situation. Well I hope you find the problem.
Irfan Rahim
irfman2000@yahoo.com
2006 Blue Nissan Sentra SE-R Spec V
Former owner of a silver 2000 Contour SE Sport ATX