Humming / Vibrating noise when Jeep is off?

[E5T0311]

I recently got an 04 Limited 44,000 miles and have noticed a deep humming / vibrating noise coming from the rear when the vehicle is parked. It only lasts for about 1.5 seconds and then is quiet for 10 - 15 minutes and it does it again. I've laid under the back end and was thinking it was a fuel pump, but when I had the key turned on the fuel pump sound is a faster, higher pitched sound.

I'm new here and have a few questions, but will post them one at a time. If anyone knows what this is help would be appreciated.

 

[tjkj2002]

I recently got an 04 Limited 44,000 miles and have noticed a deep humming / vibrating noise coming from the rear when the vehicle is parked. It only lasts for about 1.5 seconds and then is quiet for 10 - 15 minutes and it does it again. I've laid under the back end and was thinking it was a fuel pump, but when I had the key turned on the fuel pump sound is a faster, higher pitched sound.

I'm new here and have a few questions, but will post them one at a time. If anyone knows what this is help would be appreciated.

Most likely the evap system,at certian temps the evap will purge the traped fuel vapors.It could also be the evap pump(located just to the left of the fuel filter on the top of the fuel tank),which should only run when the KJ is first started to make sure the evap system is good to go.

 

[E5T0311]

So if the evap system is acting up would that be a sensor to change somewhere? Do we have to drop the fuel tank to change things on top of it?
How serious is this? Should I ignore it for a while or fix it asap?

 

[JeepJeepster]

Ive walked by mine before and heard the pump kick on for no reason. It was locked and the keys were in my pocket. Ivfe not heard it in along time.

 

[Jcode68]

Sorry to dig up such an old post, but my daughter's 06 Liberty was exhibiting the same noise last night. About every 5-10 minutes, would get a humming noise last for about 1.5 seconds. Car was turned off and locked and sitting for at least 2 hours since last driven. Not sure if it is still doing it today, will check when I get home. Initial thoughts were fuel pump, but sounds like could just be a normal noise from the evac system. Can someone chime in, is this normal? Thx.

 

[Jcode68]

Bump