My 02 Liberty makes an odd whirring or buzzing sound when I first start it up in very cold weather. It buzzes for approximately 30 t0 60 seconds then disappears. Its been doing this for at least 3 to 4 years but I don't remember it occuring when it was new. Thought I read some where on this forum a year ago or so that it might be the fuel pump but its been a long time. This is most noticeable when temperatures fall below 25. Anyone out there have any ideas?