Boost Gauge

[stuart1298 6]

I've installed my boost gauge, I have it coming of the vac pipe from dump valve to inlet manifold, I haven't yet connected the boost controller up so I'm hoping thats my problem, when the engine is off, the gauge is at "0" when the engine is runing it's sits at "-3" when I rev the car and it dumps it goes to "0" then back down where it was at "-3" I'm new to turbo'd cars so I dont no if that's where there meant to sit, help please, cheers

[Anthony 1,003]

The engine will be under vacuum (negative number) when idling or on part throttle - it will only go above 0 when the turbo is spooled up and boosting.