Brake pedal problem

1990 GMC SUBURBAN
195,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC
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DALTON WELLS
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  • 2 POSTS
Brake pedal goes to floor slightly, but barely stops my truck, everything has been replaced with the braking system except for master cylinder . When the truck is turned off the pedal will harden up but the second it turns on its more than half way to the floor.
Nov 6, 2016 at 3:34 PM
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WRENCHTECH
  • ✓Experienced Mechanic
  • 20,760 POSTS
You say everything has been replaced............for what reason? Did you have the same issue before?
Nov 6, 2016 at 7:54 PM
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DALTON WELLS
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  • 2 POSTS
When i bought the truck the metal line was rusted through and the calipers and drums were shot. So i did the front but a shop did the back end and i had to go back in because they screwed up the rear end, hardware broke.
Nov 6, 2016 at 9:51 PM
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WRENCHTECH
  • ✓Experienced Mechanic
  • 20,760 POSTS
First, make sure the calipers are on the correct side by making sure the bleeder is higher than the line in.

If that is correct, the system needs to be bled electronically using a bidirectional scan tool. You can't get all the air out of the ABS without doing that.
Nov 6, 2016 at 10:45 PM
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