mystery clicking

I just noticed an odd clicking under the hood of my 2000 XJ Sport 4.0L back by the firewall. The clicking happens about 3 times a second. I tracked it down to this component, but I'm not sure what it is...

Can anybody tell me what it is and why it's clicking?

Detail:



Location:

My 97 clicks too.. I dont know why... Anybody know??

Its normal...I want to say its some kind of pressure regulator/vacuum regulator....mine does the same, always has....

that's the purge solenoid for the emission system, some clicking is normal as it does it's thing.