Strange humming noise while idling

[scrivens]

Originally Posted by V8 EF Fairmont

I had a similar thing, but it was coming from the dash, and it turned out to be that I hadn't turned the vent switch (the one that chooses demist, face, feet etc.) to the right setting properly. Moved it to the setting proper and the noise stopped.

That's what mine was - sort of hiss/hum. Took the vent panel off to see if any of the little switch hoses had come off and found it was just the switch itself not quite on the position mark. Very quiet and annoying noise.

Does sound like the fuel pump though as the vent noise is definitely in the cabin.