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09-25-2012, 02:04 PM
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#1 |
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Registered User
Join Date: Jun 2012
Location: Science Hill, Kentucky
Posts: 180
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Power brake Vacuum
Gentlemen, I recently swapped my truck over to power brakes. I've tried both the vacuum on the intake just below the carb and the PCV vacuum. Both seem to make the truck run rough. I've adjusted the carb multiple times, can't get rid of the miss at idle and low RPMs with the vacuum hooked up to the booster. If I remove it, it runs like a top, perfrctly. Any advice? Thanks.
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09-25-2012, 02:30 PM
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#2 |
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Registered User
Join Date: Feb 2008
Location: Sidney,b.c.
Posts: 4,425
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Re: Power brake Vacuum
a vacuum leak in the booster- bad diaphram
ron |
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09-25-2012, 04:39 PM
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#3 |
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Registered User
Join Date: Mar 2011
Location: Alameda, CA.
Posts: 173
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Re: Power brake Vacuum
Agree with padresag. How does it run if you plug the vacuum line at the booster?
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09-25-2012, 04:45 PM
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#4 |
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Senior Enthusiast
Join Date: Feb 2007
Location: Spokane Valley, WA
Posts: 8,356
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Re: Power brake Vacuum
Also check the hose to the booster and the nylon inlet valve for cracks or damage. If the engine only runs rough when the booster is connected the problem is right there. Either the booster or the connections. If there are no leaks you shouldn't be able to detect any difference in engine smoothness.
__________________
My Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=444502 |
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09-25-2012, 05:00 PM
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#5 |
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Registered User
Join Date: Jun 2012
Location: Science Hill, Kentucky
Posts: 180
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Re: Power brake Vacuum
Truck runs great if I remove booster vacuum. The booster is brand new from performance online. I will check the diaphram
Posted via Mobile Device |
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09-25-2012, 05:18 PM
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#6 |
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Registered User
Join Date: Aug 2010
Location: Keller TX
Posts: 836
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Re: Power brake Vacuum
Hook the hose up and suck on it.. Funny yes but if it cannot hold the small amount your lungs can pull then its no good.. A small mighty vac would work better, but hey what works is all that counts.
__________________
62 long box with a little SBC  http://www.67-72chevytrucks.com/vboa...d.php?t=510631 http://good-times.webshots.com/album/561798652HdwqzG |
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09-25-2012, 06:48 PM
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#7 |
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Registered User
 
Join Date: Mar 2012
Location: Shallow Lake Ontario,Canada
Posts: 201
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Re: Power brake Vacuum
If you pull the hose fitting out of the booster after the engine is shut off for a couple of minutes there should vacum in the booster, if not the booster is leaking or the check valve in the fitting is faulty.
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09-26-2012, 05:49 PM
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#8 |
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Registered User
Join Date: Jun 2012
Location: Science Hill, Kentucky
Posts: 180
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Re: Power brake Vacuum
When I suck on the hose, its like sucking through a straw...so bad diaphram? Weird, it's brand new. Time to call POL. Thanks guys.
Posted via Mobile Device |
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09-26-2012, 05:56 PM
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#9 |
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Registered User
Join Date: Aug 2010
Location: Keller TX
Posts: 836
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Re: Power brake Vacuum
Well I heard a nice name for POL not too long ago and it was not very flattering.. I find that many times if you can get it local its better even if the price is a tad more as its easy to get it swapped out.
__________________
62 long box with a little SBC http://www.67-72chevytrucks.com/vboa...d.php?t=510631 http://good-times.webshots.com/album/561798652HdwqzG |
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09-26-2012, 08:39 PM
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#10 | |
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Registered User
Join Date: Feb 2008
Location: Sidney,b.c.
Posts: 4,425
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Re: Power brake Vacuum
Quote:
ron |
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09-27-2012, 01:57 PM
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#11 |
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Registered User
Join Date: Sep 2012
Location: Lawton Oklahoma
Posts: 308
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Re: Power brake Vacuum
I have found out the hard way, as well "NEW" doesn't mean "WORKS", victim of Power Steering pump.... wonderfull front seal (all "new assembly") slug PS fluid all over my Engine, frame, belts, wall, floor, ceiling, and me! Luckly it did not get in my eyes!
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