1999 Pontiac Transport Brake issue

Tiny
JUSTIN04
  • MEMBER
  • 1999 PONTIAC TRANSPORT
  • 3.4L
  • V6
  • FWD
  • AUTOMATIC
Good morning;
Recently the plastic clip holding the brake line on the passenger rear side of the van wore through causing the brake fluid to leak. We replaced the master cylinder, replaced the line and bled the brakes. Now my problem is that the brake pedal is soft, when you push it, it goes right to the floor. Not sure how to fix this problem, we re-bled the lines starting from the furthest line. We replaced the rear brake shoes and drums. We replaced the front brake pads and rotors. When the engine is turned off the brake pedal is really hard. But once you start the engine again, the pedal goes right to the floor. So after this we checked the brake vacuum booster. We removed the vacuum hose from the engine and it runs rough like it should. Then we re-hooked up the hose and shut the engine off. We then released the check valve and heard a rush of air. Which makes us think that the problem doesn't lie here. Next we removed all three of the ABS fuses and once again the brake pedal gets harder, doesn't go all the way to the floor. So now we're thinking it has something to do with the ABS. My question for you is how do you check if it is the ABS modulator? What else do you guys think it could be?
Thank you so much for your time. I look forward to hearing from you.

Justin
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Tuesday, March 11th, 2014 AT 9:34 AM

3 Replies

Tiny
GMTECH
  • EXPERT
Was the pedal good before the line went? Chances are there is still some air in the lines. Did you gravity bleed it first?
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Tuesday, March 11th, 2014 AT 10:32 AM
Tiny
JUSTIN04
  • MEMBER
Yes the pedal was good before the line went. No we didn't do a gravity bleed. How do you guys do a gravity bleed?
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Tuesday, March 11th, 2014 AT 2:08 PM
Tiny
JUSTIN04
  • MEMBER
We just did the old school pressure bleed with one guy in the cab pumping the brakes and the other guy cracking lines.
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Tuesday, March 11th, 2014 AT 2:24 PM

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