Duratec 3.0L Escape. AC off, engine warm and idling in park. Sounds kind of like like a telegraph beep----beepbeep----beep :-)

edit: sorry, this is not the engine. Loudest on driver's side towards the rear, like near the passenger door. Something vibrating I think...

Thanks

 

Kind of hard to hear, volume is weak..

 

Hmm, on my iPad and iPhone it is easy to hear if you crank up the volume. But you need a quiet background too. Thanks.

 

The answer is: fuel pump going bad! It sounded louder towards the back closer to the fuel tank where I assume the pump is located.

 

When diagnosing a fuel pump, sometimes listening through the open fuel cap/neck will amplify the sounds.. Glad you figured it out..