I think I have a good vacuum system but I have 1 line that does not hold any vacuum at all. It's a 93 LT1 by the way.

This line;



Goes to this;



And that is right here;



I am not sure what it is or if it should be holding vacuum but it does look like it is part of the AIR system. At least the control box the vacuum line goes to has 2 large hoses going to it and one goes to what I assume is the smog pump?

I was also wandering if this is the vacuum reservoir?

Last item should be your vacuum 'ball' reservoir.

Is it me or in the first picture is there an open ended vacuum line to the right of the red arrow?

The setup of those lines and valves in the first picture doesn't look right...

The open line in the first picture is where the hose plugs into. It's unhooked in the picture. They probably don't look right also because there is an extra line and check valve going to the MSD optispark for venting. Thanks for verifying the reservoir for me.

No one can help me figure out what that box is or if it should be holding vacuum?

Travis, it is in the AIR system, it's the Electric Switching Valve. It's powered by vacuum and switched by the ECM. Should have 10" vacuum at idle at the elbow.

Thanks for the reply. I will check to see what I have at idle there. Do you know if the switch should hold vacuum when I use my hand pump hooked directly up to it?

It should, the only thing the vacuum does is power the valve when the ECM sends a signal to the switch. There's a vacuum chamber above the valve and that's all.

I gotta ask, do you have a FSM?

Ok it should hold vacuum then, thank you very much. Yes I have the FSM but could not find that switch in it. Well now to try and find a replacement. Thanks again.