2003 LS Ultimate medium-pitch hum coming from behind/below right-side rear seat

[Northeast Merc]

Hello Everyone,

Has anybody had experience with a medium-pitch hum/whine coming from behind the right rear-seat area in a 2003 LS Ultimate. It begins on startup and doesn't really seem to increase its frequency upon raising the revs.

I've only had the car for about three weeks, and I think this noise may just have started. Other than this, this car with 133K really impresses me. Has better road manners than many of my hi-po cars from the seventies and is almost as fast. Much more comfortable also.

Thank you for any suggestions you can throw my way.

[FordMan77]

Sounds like normal fuel pump noise to me. Maybe try changing the fuel filter and see if it quiets down. May be getting clogged up causing the pump to work harder to maintain pressure. Never really noticed it on my 03 LX Sport, but then again I could just be tuning it out, lol..

[sxcpotatoes]

it's probably the noise of the air suspension pumping up. Just sit with it idling and try not to move around and see if it shuts off eventually.

You can see if it's the fuel pump by turning the key to the on position but not to the crank position, listen for the fuel pump hum. If you hear the hum and then it shuts off, that's the fuel pump priming/pressurizing your system. At least I think it shuts off.

I know the older cars the fuel pump can be really whiney/hum loudly.

[Northeast Merc]

Thank you FordMan77,

This makes sense to me, I'll give it a try.

[Northeast Merc]

Thank you sxcpotatoes,

I'll give this a shot. I see you have an LS Ultimate also. Great car!