Hello,

I've been researching this issue and haven't been able to pinpoint where or what my braking problem is.

88' GTU stock braking system.

This problem started about 1 month ago on and off....which makes it hard to diagnose but what happens is; when I step on the brakes, they feel firm but the car is does not slow down. Its almost like the hydraulics are not working and I have to use my leg muscle to make the car brake.

This problem is intermittent where sometimes the brakes will bite but other times I have to press down with all my might to slow down.

Any help is appreciated.

Dave

 

It sounds like a brake booster issue. The first thing I would do is check the vacuum lines for it. There's a hose with a check valve at the booster itself; this connects to a hardline, which has another hose connected to a manifold vacuum source. The booster itself could also be bad. The testing procedure would be a leak down test with a vacuum pump and gauge.

 

does the brake pressure feel the same with the ignition off?