# Vacuum cut bypass valve



## smcgypsea (Jul 5, 2014)

What does the vcbv do? and how important is it for fuel efficiency, engine efficiency, etc. I am low on funds, and am trying to determine how soon to replace it and its solenoid. 
Any help would be greatly appreciated!!!

stacy
squeezing life out of an '02 pathy


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## smj999smj (Jan 1, 2006)

As far as it's effect on fuel efficiency, the answer is it has no affect. It is part of the evaporative emissions system, which stores fuel vapors from the tank until they can later be sucked into the intake manifold and burned during combustion process, as opposed to simply venting them into the atmosphere.

COMPONENT DESCRIPTION
The vacuum cut valve and vacuum cut valve bypass valve are installed in parallel on the EVAP purge line between the fuel tank and the EVAP canister.

The vacuum cut valve prevents the intake manifold vacuum from being applied to the fuel tank.

The vacuum cut valve bypass valve is a solenoid type valve and generally remains closed. It opens only for on board diagnosis. The vacuum cut valve bypass valve responds to signals from the ECM. When the ECM sends an ON (ground) signal the valve is opened. The vacuum cut valve is then bypassed to apply intake manifold vacuum to the fuel tank.


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