Carburator cleaner vacuum trick?

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Sep 28, 2010 | 10:21 PM

Eric90XJ

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Joined: Mar 2010

Posts: 49

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Model: Cherokee

Carburator cleaner vacuum trick?

Sprayed some on the exhaust manifold and my vacuum dropped from low to lower with a very noticable drop in idle. Shouldn't it be the other way around?

Sep 29, 2010 | 08:13 AM

s14unimog

CF Veteran

Joined: Dec 2009

Posts: 1,396

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Model: Cherokee

Vacuum is entirely dependent on the valve train/ engine RPM so its entirely expected to record lower vacuum readings with lower RPMs. I'm telling you, build that pressure tester, I mentioned in the other thread, and stop guessing.

Sep 29, 2010 | 09:39 AM

djb383

CF Veteran

Joined: Nov 2009

Posts: 8,172

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From: The Republic of TEXAS

Year: 1998

Model: Cherokee

Engine: 4.0L HO

Quote:

Originally Posted by Eric90XJ

Sprayed some on the exhaust manifold and my vacuum dropped from low to lower with a very noticable drop in idle. Shouldn't it be the other way around?

I'm puzzled as to how spraying the exhaust manifold would change anything (other than the chance for a fire).

Sep 29, 2010 | 10:53 AM

Bustedback

CF Veteran

Joined: Feb 2010

Posts: 12,367

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From: Oroville, CA

Year: 1995

Model: Grand Cherokee

Engine: 4.0 with all of the noise and clatter

Quote:

Originally Posted by djb383

I'm puzzled as to how spraying the exhaust manifold would change anything (other than the chance for a fire).

Sep 29, 2010 | 11:02 AM

s14unimog

CF Veteran

Joined: Dec 2009

Posts: 1,396

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Model: Cherokee

not the surface of the manifold but the connections to the manifold, or suspected leak areas. the presence of the carb cleaner will cause the idle to drop; there should be no access so nothing should happen.

Its not a hard concept...