Booster Issue

[TS87FC3S]

so heres my issue my idle seems fine now except when i hit the brakes it drops lightly if i pump the brakes the car tries to die, is there any weird way of testing booster.. i tried pulling vaccum (vaccum pump) and it wouldnt even build 1 in/hg. But i cant hear where its leaking and brakes feel great.

[Kentetsu]

Sounds like a blown diaphragm in the booster, but before jumping to that conclusion I would take a good look at the check valve in the vacuum line.



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[TS87FC3S]

i replaced the rusted metal line with a rubber line so i dont have the check valve, i dont think.

[Kentetsu]

The check valve should be inline in the rubber hose (at least on 1st gens). If you don't have a check valve, then whenever you go above idle and lose manifold vacuum your booster will also lose it's vacuum.

[Max777]

....and you can also damage the diaphragm under boost, or so I've been told.