Power Steering problem

[ians13]

Well this is a very weird problem, whan at idle the power steering is hard, and when i turn the wheel just alittle and hold it my vac gauges drops from about 18 to 10, were does the power steering have a vac sorce and what can i do to fix this little problem.

 

[JDM 1JZ]

vac source for the p/s pump is on the back of the pump. is starts on the bottom of the accordian hose to a vac. selanoid on the back of the pump and an exit from that to a hardline that runs to the front of the motor to the intake side and then into the vsv system