Low Pedal

1990 GMC C1500
201,111 MILES • V8 • 2WD • AUTOMATIC
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MICHIGANKID
  • MEMBER
  • 2 POSTS
I have worked on a lot of brakes and never had this problem before, with engine off I have good pressure on pedal but after I start the truck the pedal goes to the floor and never regains good pressure. I have replaced the brake booster and bled the system, any help would be appreciated.
Apr 5, 2009 at 12:03 PM
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SQM
  • CERTIFIED EXPERT
  • 6,383 POSTS
Hello,

Most common cause for this to have air in the system
If for some reason the bleeding sequence is off it will not purge all the air out of the system and will lead to a soft pedal.

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

I have attached both the manual and pressure bleeding procedures below.

Please let me know of any questions.
Thank you.
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Nov 14, 2021 at 3:46 PM