I have a 1990 4runner sr5 auto v6 4x4. I just finished getting everything roadworthy or so I thought. After about 50 miles I started having a vibration coming from the front left when braking and a slight pull. No worries. I inspected everything (front and rear) and went to the local parts house for new rotors, calipers, pads and hoses. After a couple hours everything was back together and it comes time to bleed the brakes. Well I bled everything and now I have almost no pedal. I bled the system multiple times with the same result. So I started to suspect a problem with the master. I pulled it and mounted it in the vise to bench bleed. While bench bleeding I noticed the master would produce a great amount of vacuum on return. I called my mechanic and asked if this is normal to which he replied "no, if anything it should have only a very slight return vacuum but most have none". So I go back to the parts house get a master and return only to find that it will not develop any pressure at all. I get that one exchanged for another and during the bench bleed I find it to have only a very slight amount of return vacuum. So I installed it and bled the system. Still no pedal. I have checked and rechecked every connection in the entire system and can find no leaks or defects. I do get a slight amount of braking. At 15mph it will stop about 50 feet after the pedal bottoms out. I have checked the pedal height and everything is good there. I have done many brake jobs and I have never run into something this stubborn. Does anyone have any advice? Could that slight vacuum be the sign of a defective master cylinder?
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