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06-21-2013, 02:24 PM
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#1 |
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Registered User
Join Date: Nov 2010
Location: roswell georgia
Posts: 164
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vacuum leak
Any chance that a vacuum leak might affect engine performance ?
I just replaced a fuel pump... and I noticed a serious vacuum sound under the hood. I also notice that the brake pedal is now rock hard (and fairly useless!) So the vacuum noise seems to come from the check valve area on the booster... If that check valve is malfunctioning... could it have an impact on the idle of the truck? Granted there are 10 other possible causes... just thought I might get lucky and kill 2 birds with one stone. Opinions appreciated KO- Atlanta |
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06-21-2013, 02:31 PM
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#2 |
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Registered User
Join Date: Nov 2010
Location: roswell georgia
Posts: 164
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Re: vacuum leak
http://www.ehow.com/facts_5072548_sy...-leak-car.html
Well... this seems to answer the question. Maybe I'll luck out ! |
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06-21-2013, 03:02 PM
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#3 |
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Cluster King
 
Join Date: Nov 2012
Location: Junction City, OR
Posts: 5,263
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Re: vacuum leak
Pull the vacuum hose of at the power brake booster and plug it with your finger and see what that does. It sound like your check valve is defective or you have a crack or split in the vacuum hose. Very easy fix. If you plug that vacuum line and it idles OK and runs OK then you have found your problem.
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06-21-2013, 03:48 PM
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#4 |
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Registered User
Join Date: Nov 2010
Location: roswell georgia
Posts: 164
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Re: vacuum leak
Will do !
Thanks for the direction- 
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06-22-2013, 06:27 AM
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#5 |
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laying low
Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 13,113
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Re: vacuum leak
The diaphram in the brake booster has most likely failed which causes a full time vacumn leak and lean condition of the engine. You can't buy replacement parts for the booster.
Look up power brake booster on O'Riellys Auto Parts or others sites and you should find them listed for under $150 for master cylinder/booster combo. Vendors on this forum also sell them.
__________________
Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross |
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06-24-2013, 10:09 AM
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#6 |
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Registered User
Join Date: Nov 2010
Location: roswell georgia
Posts: 164
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Re: vacuum leak
All is well-
Removed vacuum hose and blocked with ratchet extension. Truck started right up and idled fine. Removed the ratchet- huge air noise and engine died immediately. Check valve was useless, new one at A Zone was $6. Also changed the grommet Brakes came back to life as hoped. Maybe we're good to go for a while ! . 
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06-21-2013, 03:38 PM
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#7 |
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Registered User
Join Date: Nov 2001
Location: Springfield, MO
Posts: 2,928
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Re: vacuum leak
most definitely a vacuum leak will mess with the idle and it will not run good. Just dig around and find it I bet you are right it is around the break booster.
__________________
Dave 1968 Custom Chevy with turbo charged 5.3 gen III 4l80e swap 1967-71 GMC 3/4 ton long step 4x4 (not sure what year exactly?) "A good friend will bail you out of jail...but a true friend will be sitting next to you saying "that was frekin awesome". "If it doesn't fit force it...If it breaks then it needed to be replaced anyway!" |
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06-24-2013, 11:20 AM
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#8 |
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Registered User
Join Date: Nov 2001
Location: Springfield, MO
Posts: 2,928
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Re: vacuum leak
great news thanks for the update. Glad you have brakes again...
I guess the truck ran good again?
__________________
Dave 1968 Custom Chevy with turbo charged 5.3 gen III 4l80e swap 1967-71 GMC 3/4 ton long step 4x4 (not sure what year exactly?) "A good friend will bail you out of jail...but a true friend will be sitting next to you saying "that was frekin awesome". "If it doesn't fit force it...If it breaks then it needed to be replaced anyway!" |
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06-24-2013, 12:29 PM
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#9 |
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Registered User
Join Date: Nov 2010
Location: roswell georgia
Posts: 164
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Re: vacuum leak
Ran well, indeed...
hauled an extension ladder in the back, cleaned some gutters. 
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