humming sound from rear like pump running
Ah hah!!! The venerable vacuum pump up to its usual tricks again!!! I might be wrong, but this is a wild guess since I had this same problem of the humming or buzzing sound from the rear and nothing else in there can make any such sound except your 10 disc cd changer while it is changing discs???? The fuel pump is under the car and it fizzes or call it sizzles, doesn't hum. Points at some vacuum leaks elsewhere in the car. The pipes or tubes won't usually leak, but the rubber diaphrams do tear after much work and need replacement. My 2 cents worth. Forgive me if I'm on the wrong track, almost bedtime, rather already past bedtime thats why.