Bvsv

[Another MkIII]

How exactly does the BVSV work? I've noticed some guys remove theirs. Is this just to clean up the engine bay or is there a legitimate reasson for removal? The vac ports are broken on mine, so I currently have the line that goes to the BVSV hooked directly to the charcoal canister. I figure if anything, it will make it run a little richer at mid throttle since it uses a ported vacuum source.I'm just kinda curious about this component and still learning the ins and outs of the 7M, so any info/explanation would be helpful.
-AM3

 

[SrBigbutt]

Mine was broken and I bypassed it I then had a friend of mine recharge my AC with R12 and saw it was broken and said that I should replace it because it could collapse my gas tank! Don't know if thats even possible. But I replaced it with a new one anyway. Now atleast it doesn't stick out like a sore thumb!

 

[bryanintexas]

bi-metal vacuum switching valve

At a certain temp, it opens to allow vacuum to pull the fuel vapors through the charcoal cannister, and dump them into the intake tract, to be burned. Iirc, the port for it is pre-t/b, so the ammount of vacuum applied depends on the distance the throttle plate is open.

Mine is gone due to no more charcoal cannister.

 

[gaboonviper85]

Ever notice the hiss you hear when you remove the gas cap?...this is pressure that gas fumes build when it heats up a bit...our cars are supposed to build about 5psi of pressure in the tank to stop fuel pump cavitation....when the tank builds too much pressure the charcoal canister (evap canister) filters the fumes threw charcoal as it bleeds the tank for emissions control, cause bleeding raw fumes is stupid and a potential fire hazzard...the bvsv is what makes it do it's job!

Removing a charcoal canister is not a good idea unless you have another means of bleeding the fuel tank of access pressure without relieving too much as you always want the proper amount as we have intank pumps and sumpless tanks! The canister is huge and ugly but it has a job to do and it can't do it without the bvsv...

Driftmotion has new bvsv valves for $48 ish....as well as your local Toyota dealer.

 

[Nick M]

Ever notice the hiss you hear when you remove the gas cap?...this is pressure that gas fumes build when it heats up a bit...our cars are supposed to build about 5psi of pressure in the tank to stop fuel pump cavitation....when the tank builds too much pressure the charcoal canister (evap canister) filters the fumes threw charcoal as it bleeds the tank for emissions control, cause bleeding raw fumes is stupid and a potential fire hazzard...the bvsv is what makes it do it's job!

Removing a charcoal canister is not a good idea unless you have another means of bleeding the fuel tank of access pressure without relieving too much as you always want the proper amount as we have intank pumps and sumpless tanks! The canister is huge and ugly but it has a job to do and it can't do it without the bvsv...

Driftmotion has new bvsv valves for $48 ish....as well as your local Toyota dealer.

:thumbup:

Maybe people should start chopping their arms off, to clean up their body lines. You don't want that ugly appendage hanging there anyway.

 

[jdub]

Gaboon is correct...the FP needs positive pressure (~2 psi) in the tank to prevent cavitation. The check valve that makes that happen is in the charcoal canister...removing it is a bad idea. It's simple to get a JDM canister and install in the wheel well out of sight.

The BVSV is not absolutely required. It's purpose it to let the engine warm up before gas vapor is vented to the TB under vac. The BVSV is there to improve emissions...it prevents an excessive rich condition when the motor is in warm-up enrichment (low coolant temp).

The early 7Ms did not have a BVSV...the vac line was routed direct from the canister to the manifold. You want to use a BVSV to max efficiency on the engine, but routing it direct is a whole lot better idea than removing the CC.

 

[deabionni]

Driftmotion has new bvsv valves for $48 ish....as well as your local Toyota dealer.

If you don't mind buying used, your local junk yard would have them pretty cheap; and you can pick them up on Ebay for 99 cents.

 

[Another MkIII]

Thanks for all the info guys. I do intend to replace mine (if I keep the car), I just have other issues to address first. I currently have the line routed directly to the canister with the BVSV bypassed. I'm not one of those crusaders for a clean engine bay. The car actually didn't have EGR when I bought it, and I bought an EGR and installed it before I drove the car. If it has a reason to be there, it will be there.
-AM3

 

[tlo86]

i say just buy the 99 cent one and wait for it to come. a couple of days at worse wont do a thing to your car.

 

[Another MkIII]

i say just buy the 99 cent one and wait for it to come. a couple of days at worse wont do a thing to your car.

I know that, I was just curious as to its purpose/how it works. I have the line bypasssing it and running directly to the canister, so everything should work fine, it will just run a little richer if anything. And According to an earlier post, only the time the car is warming up is affected.
-AM3

 

[tlo86]

I know that, I was just curious as to its purpose/how it works. I have the line bypasssing it and running directly to the canister, so everything should work fine, it will just run a little richer if anything. And According to an earlier post, only the time the car is warming up is affected.
-AM3

yup nothing big. ive ran the cars without the canister until the right parts came in before. i dont foresee a problem unless its over a year + of sitting or driving.