little to no brakes when when booster vacuum disconnected

[JeffP1167]

Is this normal? When I do it I can barely stop my car. Can barely even move the brake pedal as well. This is on my 97 firebird, also with vacuum. They brakes feel different then my 97 camaro.

Bad booster?

 

[Kid Vette]

Why not just connect the booster? Am I missing something?

 

[JeffP1167]

Why not just connect the booster? Am I missing something?

I am trying to find a P0300 solution and was wondering if this booster could be leaking based on what I said about it and it possibly causing a vacuum leak.

 

[mrvette]

Why not just connect the booster? Am I missing something?

I am trying to find a P0300 solution and was wondering if this booster could be leaking based on what I said about it and it possibly causing a vacuum leak.

Every vac booster I ever seen, has a check valve on the big round canister, GM's are typically white, and the vac hose goes to mani full vacuum, to that check valve....I would start engine, let run a few seconds, then pull the valve outta the rubber grommet you should hear a large inrush of air and a woosch...if you don't you either have a bad check valve, but blowing through it one way or another will prove that, or you have a bad booster, not holding vacuum, when you do this test, don't be pressing on the brakes, that will use the stored vacuum assist....

:hi: