Emissions system question

[workingdog]

I've got my emissions manual and I'm looking at it and I'm not clear on a couple of things.

What is the purpose of the vapor separator?

Why does the line running from the separator to the charcoal cannister run to the other side of the truck before going forward to the engine compartment?

What's the purpose of the BVSV and the advancer port?

Thanks

Peter

 

[Dirty Toad]

I can't answer any of these questions, but if you need any parts for your emission system let me know. I just tore all mine out. Love the de-smog.

 

[workingdog]

Don't need any parts, trying to figure out what's there so I can split it into my Vortec and hopefully be legal in California.

Peter

 

[Fast Eddy]

What is the purpose of the vapor separator?

It's the first stage where fuel can drip back into the tank instead of evaporating

Why does the line running from the separator to the charcoal cannister run to the other side of the truck before going forward to the engine compartment?

F' if I know. It's the same in a '40. Weird.

What's the purpose of the BVSV and the advancer port?

If I know what you mean, the advancer port is where you connect your distributor vacuum advance to the carb. The BVSV is a vacuum switch that goes into the thermostat housing and opens a vacuum port at a certain temperature, depending on what color it is.

One use of a BVSV is to control when the charcoal canister is vented into the intake. My '78 fj40 has two of them. I think the other one controls the egr valve.

I don't normally read this board. Send me a PM if you ask a question and I ignore you.

 

[2mbb]

I think the tortuous path line that runs from the vapor separator to the charcoal cannister is something like an evaporator. Any liquid gas that makes it past the vapor separator is given a chance to evaporate before reaching the charcoal cannister. The activated charcoal can only adsorb gasoline in the form of vapor. Any liquid gasoline that gets in there would drip out the bottom, defeating the purpose of the system.

If you study the overall schematic shown on page 3-3 you will see that the BSBV (1) is connected to both the distributor advance as well as the charcoal cannister VCV. At high rpm/load (high advance vacuum), the activated charcoal is flushed with clean air to strip off the adsorbed gasoline vapor. These vapors are sucked into the intake manifold and burned in the engine. The BSBV is a temperature switch so this only happens when the engine is sufficiently warmed up.

 

[workingdog]

Thanks for the information,

So the VCV is the valve and the BVSV drives the valve based on temp? That makes some sense. But the loop over to the driver's side would act as a condenser, not as an evaporator - wouldn't it? Not that it really matters. I thought that perhaps on some models there was something to connect to on that side. I noticed that the power steering line makes the same kind of loop along the bottom of the radiator.

Peter

 

[Fj60Ed]

So when we desmog the engine we want to leave the bsv , just run a single line to the distributor and not the canister? what other valves should we leave?

 

[workingdog]

The vapor cannister isn't hurting performance (that I'm aware of) and it is keep a lot of gas vapor out of the air. Might be a nice idea to leave the vapor system intact.

Peter