fitted my new boost gauge to my saff yesterday. all went well, and when completed, i started it up, read a vacuum and all was fine.

took it for a drive and it continued to read a vacuum even when coming on boost.

popped the bonnet, all was still plumbed in, but looked at the pipe off the inlet manifold, that i had te-ed off from and it seems to have a little plastic gubbin in it, before my tee, which i can only assume is a one way valve?

will need to re-plumb it in, but just wondering what purpose this pipe serves, it goes from the inlet manifold, along the bulkhead then disappears under the windscreen wiper mech??

anyone got any better places to plumb a boost gauge from?

cheers