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

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 !

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.

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.

Re: vacuum leak
 

Will do !
Thanks for the direction-

:gmc2:

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.

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 ! .:bann:

Re: vacuum leak
 

great news thanks for the update. Glad you have brakes again...
I guess the truck ran good again?

Re: vacuum leak
 

Ran well, indeed...

hauled an extension ladder in the back, cleaned some gutters. :hh: