ps pump

my ps pump is shooting the fluid out the hole in the cap. even at idle. i have never seen this before. i know that if you turn the wheel with the engine off it will do this. but mine is doing it all the time. it use to do this after i wheeled it and the fluid heated up. but now it does it all the time. anybody else had this problem. my xj is a 90 4.0 at . i am taking it to get it replaced on monday. if i keep fluid in it ps works fine. any help would be great.

thanks Brent