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  1. #1

    Default brakes issue ? need some help please ..

    1990 k1500.. pedal hard at park and does not stop when put in drive .. pedal hard at low speed and does not want to stop but at cruising speed stops just about normal.

  2. #2


    Hmm.. could be a small vacuum leak it sounds like?

    Engine not creating enough vacuum to create the "boost" in the booster, but at higher engine speeds creating enough.

    I'm sure someone else will step in and give input as well.

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  3. #3


    Try putting the truck in park, revving up the engine, then trying the pedal.
    Does sound like you have a small vacuum leak.

  4. #4
    Sr. Engineer
    Join Date
    Oct 2010
    Indianapolis, In


    Don't rule out bad vacume booster diaphram.
    2000 GMC YUKON SLT, 5.3L tow pkg, G80 rear/w 3.73 gear

  5. #5


    Quote Originally Posted by dpeter View Post
    Don't rule out bad vacume booster diaphram.
    was gonna go there next if other didn't solve the problem.

  6. #6


    sounds like my old mustang. had a bad booster leak. only stopped when up in the rpm range.

  7. #7


    well i just bought a master cylinder because its leaking anyway and the dont have the booster in stock .. anyway to che vacume on booster?

  8. #8
    Sr. Engineer
    Join Date
    Oct 2010
    Indianapolis, In


    Get a hand held vacume pump and draw a vacume on the booster and see if it holds. Might be able to trace it to the booster by removing vacume line and plugging it to see if engine idle changes with it on and off.

  9. #9


    i pulled the vaccume line off .. engine is sucking .. i think its the booster because the problem persist with the vaccume line off leading me to believe the booster is not getting vacume ..

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