Boost gauge query
 

I recently fitted a ProSport boost gauge, it shows boost like it should, but the gauge also spins round to the max position when I brake, it didn't do that when I first fitted it, but it does now. Any ideas?
Car is a Ver6 Impreza UK model.

Did you go into the right vacuum pipe?

I used the spare pipe to left of coil pack which was blanked off, seems to be the one others use for boost gauges.

Is your dump valve maybe stuck closed? Have you checked the vacuum hose going to it?

I'll check the pipe, can check valve too, I assume that if the vale is free to move it should be ok, is there any other way to check operation?
Thanks for the reply

It'll have a spring holding it closed so there'll be a decent amount of resistance. It should be able to slide closed freely though once you've pushed it open. Is it aftermarket?

It is a standard valve, took it off earlier, seems to be sliding properly so refitted, start engine, pressed brake pedal and it had no effect on gauge, took the car for a drive and its doing it again! Looks like its a problem with the valve then. might take it off again and give it a good clean to see if that helps, if not , I'll have to find another. Thanks

Is the vac hose going to the top of the valve ok?

Yes, the hose from the valve that runs to the inlet manifold looks fine.