So last night i noticed a hissing noise coming from the rear of the XJ, i've never heard it before, could it be the fuel pump? and if it is, is that a sign to replace it? Also, last night i was inside of the xj with a flashlight and noticed i had a clock in the dash, its never worked since i've had it, i started the xj to see if it would come on, and it is on but very dim, you cant see it unless you shine the flashlight on it, its as if its too dim, is there a way to brighten it, i tried the headlight switch to adjust the brightness on the gauges, but nothing, Thanks guys!!!

 

Yup. That's probably the sound of your fuel pump. Nope, not unless it's running badly as-if it was fuel starved. Does the way it runs depend on the fuel level or is it okay at all fuel levels? If it ain't broke don't fix it.

The clock's likely got a bad electrical connection - like where the ground wire ties in.

 

No, its not running bad, so i guess its ok. and where would the ground be, behind the dash?

 

not a ground, its a simple 4 pin connector grounded somewhere down the line.
There is a small lightbulb in the back of the clock, replace it.

 

oh ok, will do!! Thanks!!