I just bought a 97 blazer the abs light is on and the braking performance is poor. The previous owner recently replaced the master cylinder and front calipers. I tried gravity bleeding today and was only planning to do the front so I did the passenger side first and it went quickly and as expected, the driver side was still sending out a constant stream of bubbles after an hour and a quart and a half of fluid and never stopped so I gave up on it and decided to go ahead and bleed the rear and the passenger rear was still sending out a constant stream of bubbles after 20 minutes so I gave up and did the driver rear which didn't put out near as much bubbles but never stopped bubbling although it did slow down after about 5 minutes. I traced all the brake lines and didn't find any leaks that might allow it to suck air.
The braking performance is still terrible although it did stop well the first couple times I applied the brakes after all this.

I have used the search function and didn't find an answer.

​​​​​​