I've got a 1998 Chevy K-2500. Lately I've noticed that it sounds like the fuel pump in constantly whining. When I first turn the key on the fuel pump activates (whines) for about 3 seconds then shuts down. (which I believe is normal) When the truck is running it whines all the time. Anybody have any insight as to what the problem might be? Other than that the truck runs fine. I'm just afraid someday it's gonna quit on me.