What does this VCV do ??

[Spike Strip]

Can't find this Vacuum Control Valve in the FSM or Emissions manual ... What is its function ? What system control, if any?



(Apologies to whomever I borrowed this picture from )

 

[Dynosoar]

That VCV controls the charcoal canister if I am not mistaken (99% sure).


Dynosoar

 

[cruiserbrett]

I think its for the distributor vent?

 

[Joe_E]

I believe when one of the BVSV in the water neck heats up and opens, it allows vacuum to the VCV thereby opening it and allowing fumes (i guess) from the charcoal cannister to be drawn into the carb and burned.

Of course i could be completely wrong.

 

[Joe_E]

Okay, actually there are two VCV that are alike. The one you are pointing to like cruiserbrett said is probably for the dizzy cap vent.

 

[Spike Strip]

Yeah, it has a hose line to the Dizzy - one to the Air Cleaner - and one to the spaghetti tube... I guess it's something to vent the dizzy under specific conditions... Just wondering what those conditions would be... ?

Thanks for the input!

 

[Joe_E]

I would guess that being hooked up to the VCV that the dizzy cap will only have positive ventilation when the engine is running and drawing vacuum by way of the air cleaner.
The VCV would probably shut when engine is off so moisture and mouse piss doesn't creep into the system and cap.

 

[Spike Strip]

Yeah, Joe_E, that's prolly in the ballpark --

And I'm glad I checked that VCV! It wasn't holding vacuum - no resistance at all. Valve is just a diaphragm that allows flow with vacuum, blocks it when no vacuum... Thing would've been a big vacuum leak!

 

[hank14]

That's also the VCV that allows gas fumes to build up in the distributor when it's not working. You'll hear the infamous pop in the cab when you start the engine. Mine was bad, and checking the VCV per emissions FSM and replacing when it was bad fixed that problem for me.

 

[Dynosoar]

Hey Alf,
I have one sitting in my garage that I am not going to use it is yours if you want it.

Dynosoar

 

[Spike Strip]

Hey, thanks very much, Peter, I could use it... You mind shipping, if you have time ? I'll PP the postage... ?

 

[2mbb]

you can see it in this schematic:

http://www.sweetillusions.org/toyota/6.pdf