So I replaced my thermostat housing and as I was putting the car back together I realized I forgot to mark the two lines that go into my vacuum switch. So my question is, based on my picture does anyone know which line goes over which port? And why?



My vacuum switch and the two mystery lines.

 

You wont get any responses from any reputable sources unless you provide more info. All anyone sees here is the same exact thing you see. Two lines, and Two places to connect.

Trace both vac lines back to where they end. Give that info, and it might help. You may also just do a search here for the vacuum diagram for your car. That would be the best way to ensure you are correct in the end.

 

Then theres always the first thing I would do in this situation. Let the lines relax and chances are they wind up where they were, or close. 50/50 chance in Vegas is pretty good, why not here?

 

That looks like the EFE TVS.

Bottom nipple goes to the EFE valve; top nipple goes to vacuum source. Probably a T that's downstream of a check valve.

See here. https://www.thirdgen.org/forums/tech...rams-i.html#25

 

I couldn't find any vacuum diagrams in here for my 1987 Firebird Formula. I took a few more pictures though if anyone can help me. The vacuum switch is marked #1 for the top port and #2 for the bottom. I'm not sure if this is of any importance though.




Vacuum switch with each port numbered.





One of the lines is very short and goes right back to plug in right under the carbeurator.





The other vacuum line is very long and travels down past the exhaust manifold on the passenger side and plugs into a gold cylinder thing just below the fan switch.

 

Thank you! This sounds like what i was looked me for. One line does attach to a T in the hoses and the other to the EGR valve.

 

The carbed cars all have pretty much the same plumbing; year, how many cupholders, sticker package, none of those things really is any different from any other.

The "gold cylinder thing" is the vacuum motor for the EFE valve. That line goes to the bottom nipple. The other is the "vacuum supply" (sorry for the oxymoron). Yes it does matter which one goes to which port on the TVS.