I gave the GL an oil change today, and pulled the air cleaner to inspect the carb and such. Came across a mystery vac line, that is connected to nothing.

 

For starters, what is this thing? What is it called? It is a plastic canister of some sort. It has two hose coming from it. One connects to the rear of the carb. The other.....???

 

 

When pulled away, I find this hose, that isnt connected to anything...

 

 

The car seems to be running great.....

 

But Id like to find this hose a home!

 

Any help is greatly appreciated!

Have you Checked the Carb for open ports?

No open ports, that I can find.

 

But the previous owner did have the motor out for headgaskets. So things might have gotten mixed up a bit.

 

As I said though, it runs great.

 

I just got back from a trip to Seattle. Logged more than 700 miles, and got a bit better than 27mpg

 

I just need to find a home for this hose!

What year/model?4wd? Calif? O2 sensor equipped?

 

Where exactly does the connected hose connect?

It is an '84 GL, 4wd.

 

non-CA, and no O2 that I can find. It does have EGR and and a charcoal canister though.

 

The hose that is connected connects to a port on the top rear of the carb. The port it pointed straight to the drivers side fender, it is tucked up near the aircleaner.

 

 

Here you go....

 

 

 

 

Thanks for any help!

Edited December 7, 201015 yr by Idasho

I think that is the "bowl vent vacuum valve".

 

The other end of the line should tee into "thermovalve IV" which is mounted on an insulator on the intake just to the drivers side of the carb.

It should tee into a line from the "air control vacuum valve" before attaching to the themovalve.

The air control vacuum valve is similar w/4 ports.

Thanks for the help. We might be getting somewhere!

 

Now, the other day I took a long look at the under-hood diagram

 

 

And using the preformed bends in the hose that doesnt have a home, I found that it DOES line up with a T-fitting that attaches to that thermovalve. Only problem is that the T-fitting had a cap on it. So I removed the cap, and hooked the hose up. I thought I had things figured out....

 

Then I started the car. The motor idled a bit rough, and REALLY stumbled when you tried to rev it. So I put it back how it was, and here we are.

 

So what does this mean? Can these thermovalves go bad? Can they be removed and cleaned? or do they just get replaced?

 

And for the simple sake of conserving my sanity.... Im going to link to a few threads that may be of use, so I have a means of finding the threads again....

 

http://www.ultimatesubaru.org/forum/showthread.php?p=954684

 

http://www.ultimatesubaru.org/forum/showthread.php?t=86087

 

http://www.ultimatesubaru.org/forum/showthread.php?t=86141&highlight=stock+carb

 

http://www.ultimatesubaru.org/forum/showthread.php?p=756025

Edited December 7, 201015 yr by Idasho

AHA!!

 

According to GD's thread here....

 

http://www.ultimatesubaru.org/forum/showthread.php?t=86141&highlight=stock+carb

 

The thermo-vacuum valve simply controls the flow of vac. to the canister, as a sort of choke.

 

i think Ill just bypass it.....

 

Opinions?

That paticular TVV doesn`t have anything to do w/the cannister.

 

It vents the carb bowl to atmosphere thru the self contained air filter on the BVV above 60C.

 

It also opens calibrated air bleeds in the carb to lean the mixture a little.

 

Sounds like the BVVV is bad.Probably why it was disconnected.

It should hold vacuum applied to the lower port.(bet it doesn`t)

 

Since your car runs well,I wouldn`t be too concerned,but, it might be even better w/a junkyard part.

I need some help on where a couple lines go from the carb. I can see that #1 goes to A, the bowl vent vacuum valve. Can someone help tell me where #2 & #3 go please? It's probably really easy, but I want to get this right. Thanks!!

 

Heh - that's a mess. And no - it's not at all easy to determine where that stuff goes unless you work on them a lot and keep it fresh in your memory.

 

It looks like you have a CA emissions feedback carb - I think both #2 and #3 are metering ports that should connect to the metering duty solenoids that are mounted to the manifold near the carb..... best guess from memory.

 

I haven't worked on one in a while - I just unbolt them and drop them directly in the trash compactor...... When I work on carbed Subaru's at all anymore - these days it's mostly about the newer EJ stuff and I dumped all my Hitachi's on my personal rigs years ago.

 

GD

Thanks, That's not my exact car, but the carb is identical. I have a non-feedback CA emissions car. Knowing that those are metering ports that need to see vacuum will help. Jerry got me a known good carb, so I will put that on and hook it up to vacuum to see how it goes.

They don't get constant vacuum - there are valves and plumbing and orifices..... they don't receive a constant signal and if you hook it up that way it will run very poorly - the amount of vacuum they receive and when is dictated by carefully designed pluming that changes state under certain throttle conditions and specific temperatures - it all works together and that's the crux of why I eventually gave up on the stock carbs. I couldn't stop them from needing that metering plumbing and thus their ability to be "stripped" for a clean engine/bay is limited. I decided the design was too complex to be used in the way I wanted so I just stopped using them. Now you see why.

 

When I stripped the carbs of all that stuff I just plugged the metering ports off. They seemed to run best this way vs. open or given constant vacuum. Which isn't saying much because there was always problems without the proper metering signals. The carb just wasn't designed to not have that stuff.

 

GD

I have all the OEM orifices, just don't know where to hook them up. You gave me the insight I think I needed. Plugging them off is my backup plan. Much appreciated.

Hello,

 

The black device is called the air control vaccum valve. The loose end you are referring to connects to one of the ports on the air filter housing.

 

 

 

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