Unknown vacuum line on engine

[OldFox]

I've got most of the connections figured out on my 85 engine, but the one I'm not sure about is the large vacuum hose that comes from inside the passenger inner fender behind the shock tower, connects to a metal line on the intake, runs along the valve cover on the drivers side, and connects to the front of the carb/intake at the base. At first glance I thought it was brake booster due to size but that is on other side, so I can't think of what or why there would be a large vacuum hose like that going to inner fender, here are photos...

[Chuck W]

Connection from the charcoal canister?

[OldFox]

Onto something here...

http://vb.foureyedpride.com/showthre...d-Hose-Routing

[WilliamCapri]

I may be wrong but I think this line goes to the Cali required emissions stuff. There’s a rats nest of components inside the ps fender and it’s all stuff to lean the air fuel mix when going to higher elevations.

[OldFox]

Thanks, I will look at it again closer tomorrow, car was sold in Illinois originally so I don't think it was CA smog originally.

[qikgts]

These two threads will get you fixed up.

http://vb.foureyedpride.com/showthre...1985-Emissions

The stuff in the fender is not exactly what I would call emissions stuff. It's more like calibration stuff. What's in there is a series of bleeds and solenoids that work in conjunction with the barometric sensor for high altitude operation. Better discription in the below link.

http://vb.foureyedpride.com/showthre...tle-What-is-it

[OldFox]

Thanks for the links, read through them and this post makes the most sense...

"The barometric sensor on the 85's controlled the bleed solenoids located in the wheel well. There is a tube that runs in from behind the inner fender, meets up with a metal tube at the back of the intake, runs under the throttle bracket, then changes back to a rubber tube that connects to the EGR spacer. The only purpose of the barometric system on our 85's is to bleed extra air into the manifold to compensate for the thinner air at altitude."

...but the only part I don't understand is how its not creating a vacuum leak since its below the carb base, wouldn't it be sucking air just like brake booster source at the rear of intake?

[qikgts]

I believe there are normally closed solenoids in the circuit between the line from the carb and the "trunks" with the bleeds in them. When they activate, the vacuum leak happens leaning out the mix.

There is a little more info in the EVTM.

[OldFox]

Gotcha, that would make sense the "default" is closed because most of the emissions has been removed on this car including the EGR (block off plate) which I don't mind because its setup old school simplistic with the original carb. However I do like the fact they left both front & rear carb bowl vent tubing intact along with all the other fuel vent system components that go to box under battery so it doesn't stink up the garage. I assume the fuel tank/carb vent systems still work to some degree "at rest" by default without any solenoids or switches. I'm just verifying everything to make sure there are no loose ends and/or vacuum leaks before I dial in timing and carb.

[85GTGuy]

Is this car an automatic? or manual?

[OldFox]

Carbureted has manual in 1985 (CFI/TBI is automatic).

[qikgts]

Gotcha, that would make sense the "default" is closed because most of the emissions has been removed on this car including the EGR (block off plate) which I don't mind because its setup old school simplistic with the original carb. However I do like the fact they left both front & rear carb bowl vent tubing intact along with all the other fuel vent system components that go to box under battery so it doesn't stink up the garage. I assume the fuel tank/carb vent systems still work to some degree "at rest" by default without any solenoids or switches. I'm just verifying everything to make sure there are no loose ends and/or vacuum leaks before I dial in timing and carb.

Currently all the emissions equipment is still intact on my car too except for the cat, air pump, thermal valve in PCV line, and heat riser. Air cleaner servos are hooked up but the tubes aren't. No issues with driveability ever. No stink after driving is a big plus. Shift light still lights up. Can't ask for much more from a rather complex, almost 40 year old pre-computer controlled engine combination.