Let me re-word the question please. Where does the 3mm vacuum hose go with the question mark by it in the drawing or does it get plugged? I am questioning the very small vacuum hose (3mm or 4mm) shown in the picture that is vented to the atmosphere just to the right of the decal valve in the picture. I question this because the hose goes back to the air box and that would be unfiltered air going into the engine.

Second question. What hose hooks to the tiny black plastic line in the engine compartment that goes through the tunnel to the reservoir on top of the gas tank. (No canister in engine compartment). What hose in the engine compartment hooks to the very tiny black plastic line that is in the engine compartment near the fuel in line and the fuel return line. I believe it is a line that goes to the evaporation canister on top of the gas tank.
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No the vacuum hose going to the decel valve and fuel pressure regulator should not go to an open port in the air filter housing. Not only would you be getting dirty air ,you wuld have no vacuum to the decel or fuel press reg.


Pelican Parts has good diagrams on the site:
1.8 Fuel & Vacuum Diagrams


Jim

There should never be a direct connection from the outside to the manifold. Especially on a 1.8--unmetered air is something you really do not want.

Let's see. The Decel Valve should get hooked to manifold pressure. The fuel rail as well. And the AAR and DV both let air from "in front of" the throttle valve to the manifold, so they each have large-ish connections to the manifold.

The distributor dashpot will have hoses going directly to the throttle body--likely only one, as most of the 74s did not have vacuum advance. The single connection on the throttle body would plug into the fitting on the distributor dashpot that points back toward the distributor body, while the other would be left open.



The second question: It sounds as if your car has the engine-bay-mounted charcoal canister. The small hose hooks to the small fitting on that, and goes up to the expansion chamber on top of the fuel tank. (Earlier cars had the canister on top of the fuel tank, with the two larger air lines running along the driver's rocker panel.)

--DD

I reworded the question because it may have been a bit confusing the way it was written. Thank you. Hope you can help me. No EGR, not a California car.

This is from the Pelican diagram page I linked to in my first post.
Ignore the EGR valve hoses and the rest should apply.

Jim


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Please EDUMAKATE me.
I have a 2.0 and a slightly different set up but what's the fuel pressure regulator being connected to the decell valve and then the plenum for?

The end of the pressure regulator is the adjustment knob. Something looks screwy with the diagram.

2.0L Fuel press reg is different than the 1.8L.
1.8L Fuel press reg uses vacuum change to make a slight pressure change between Idle (no load) and WOT (full load).

Jim