yet another noise, 2000 Silverado

Here's another noise for the Chevy Silverado archives, my son's truck has a weird noise that is hard to explain, it did it this morning when cold, idling in park, it's a grinding/vibrating noise, almost like a pump or motor whine, I could not locate it, but it went away when warm. It could be a pump cavitating or something that sounds like a vibration on sheet metal. Don't know if anyone else has seen this but it is definitely a new one on me. Since the only things running were the engine and tranny this may be hard to determine, until it gets worse as someone suggested. But there are no check engine lights on or other warning signals, I just thought I'd see if anyone else has experienced this and can tell me what in the heck it is. Thanks!

Next time its cold turn the key to the run position but dont start the truck. If you hear the noise for about two seconds then stop, your fuel pump is getting noisy. This doesnt mean its bad either, my 99 has been whining forever.

I have a 99 and have been experiencing the same noise when cold started. I know what your talking about and the noise is hard to pick out, sound like a vibrating but cant tell exactly where from. It seems to go on and off inconstistantly. Not to sure what it is either

well noises...... mine are as follows
(1) ABS system runs non stop when fuse is installed due to bad relay
(2) speakers have that blown crackling sound anymore
(3) rattle from transmission, torque converter dust cover - only when motor cold
(4) carbon knock when motor cold
(5) tape player rattles only when tape in drive when used for auxillary imput for satellite radio
(6) noisy door and window seals

Yet I still love my truck .......... 10 years later 165000 miles and counting....

yes i agree on noise in fuel pump i ran accross one noisy pumps and i done same thing he's telling you i had the guy start it and sounded like fuel pump then i had him just turn key on and it was indeed the pump.