Fuel vapors and Charcoal Canister plumbing to VCV & BVSV

[HKforte]

I am having an issue with fuel smell in my cabin, whether the top is on or off. I replaced all the gas tank hoses with new ones, including the sending unit seal & I still have a strong smell of fuel. After reading responses from Pin_Head on this forum, I realized that my desmog had a lot to do with the fuel smell, and I'm not talking about the fumes exiting the exhaust.

From my understanding, the VCV (Vacuum control valve), and it's plumbing to the charcoal canister and manifold vacuum remove most of the fuel vapors from the gas tank, significantly reducing the smell of fuel.

The VCV is connected to the BVSV switching valves which control when the VCV opens or closes based on radiator temperature. My BVSV switching valves are not functioning properly, so I have the following question:

Is there a way to connect the VCV valve without the use of the BVSV check valves so that I may reduce fuel vapors in my cabin? I don't know enough to understand why the BVSV valves are necessary to regulate the function of the VSV, so any input on that is appreciated as well.

 

[Fast Eddy]

You can get one new BVSV and route the output of the evap can directly through it and into the air cleaner. Someone else suggested this in a thread somewhere, maybe Pinhead. You could also just route it directly into the air cleaner without a valve. You may want a check valve in the line so air isn't circulating through the system when it's parked due to temerature and other enviro changes.

 

[MoCoNative]

The original designs called for the vapors to be fed into the manifold only after the engine was warm. Hence the BVSV in the newer models. In some cases, the speed sensor on the speedo may have affected it too, by limiting it to times the vehilce was over 40 or something like that. There are some variations through the years.

I have the stuff to put it back on mine, due to the PO desmogging it a very long time ago. Years ago, due to smell I ran a line like the charcoal canister line did, to just a simple filter under the hood. Not ideal though, as I am releasing vapors under the hood. Helped with expansion issues and smell in the cab though.

I'm not sure what constant vacuum to the canister will do to you. Stock took vapors from a small expansion/condensation tank in the cab. There is a check valve there also. Then on to the charcoal cansiter. Then the primitive ECU determined, based on engien temp, speed, etc... when the VSV opened and closed allowing the vapors to be pulled from the charcoal cansiter. The canister is only temp storage for hot days, when the tank expands, so the vapors can be burned next time the vehicle is driven.