Ferrari Mailing List: electric problem (Non Ferrari question)

[James V. Cunningham (vikelj]

I am installing water injection on my Porsche 911 which has been 
supercharged.  I am doing it my self and need some help.  I have a 
water pump, solenoid and hobbs switch.  I am using a four pole 
relay.  I have connected the positive side of the pump and solenoid 
to pole #87 and the negative side to pole #85.  Poles #86 and #30 are 
both connected to the battery.  Where do I place the hobbs pressure 
switch so that when I reach a certain boost, everything comes on?  I 
can get the pump and solenoid to work when I apply positive current 
to #30 and #86 but it seems that no matter where I place the hobbs 
switch, either nothing works or it works without the hobbs switch 
applying the vacum when the boost comes on.  I don't want it running 
all the time, just when I reach a certain boost (4 lbs).  Thanks.
Jim

James V. Cunningham, Esq.
410-625-7400
http://home.comcast.net/~vikelj/page3.html