So that's why my car stinks of washer fluid too......Mine does the same and washer fluid runs back into the tailgate cover. The fault is the metal tube that runs up the middle of the motor has broken. There is a fix kit for this so you dont have to replace the whole motor.
I'd guess that the hose has come off mate. Have a look in my FAQ post (link in sig) and there's a further link to a "how-to"mine doesn't squirt, I haven't looked yet but do they clog up? and i'm assuming the washer bottle for the front supplies the back too is that right?
probably should have looked at the common probs page first!
i'll get me coat