[VaderSS]

I have an '88.5 California emissions Samurai. It has a rebuilt engine and rebuilt carb on it.

My carb does not have the second port, shown open here;

The previous owner had the vacuum line for the vapor canister plugged. The lines to the carb vent and tank are in place. I am wondering where to hook the vacuum line up to pull the vapors out of the canister.

 

[Baratacus]

The canister vapors are drawn into the throttle body's main throat through that throttle body vacuum port. If you don't have a port for the vacuum then you can "T" into the one above it. It just has to port into the throat of the primary barrel between the choke plate and the throttle plate.

 

[VaderSS]

Thanks for the response.

The other port is for the vacuum advance on the distributor and the egr valve actuation.

I tried attaching the canister line to the port that provides vacuum for the carb heat valve, which is straight vacuum, and the engine acted like it had a major vacuum leak. This causes me to believe that the canister flows with very little restriction.

If I teed the line for the egr and vacuum advance and attached it to the canister, I'm pretty sure that the vacuum advance and egr would be disabled as all the vacuum signal would be disapated.

 

[Baratacus]

Puting the canister on the manifold vacuum would cause a vacuum leak and a "Too lean" condition. You're drawing an excess of 30 in Hg off the manifold pressure at idle. That's why the canister is ported vacuum.

as for sapping the vacuum from the EGR and the Vacuum advance:

The Vacuum advance line should be "T" fitted to the bi-metal switching valve on the manifold. That Bi-metal switch is a thermal switch that should then have it's switched line going to the EGR modulator. EGR modulator will only pass vacuum to the EGR if the BVSV is open and the electric VSV next to it is open. The Computer controled VSV next to the modulator will close when the High altitude Compensator is on or when you are in overdrive. (just learned that last week) When there is vacuum through the modulator, it will only pass it on to the EGR valve in proportion to the backpressure from the exhaust. The rest of the vacuum that the Modulator doesn't pass on to the EGR valve is vented. Basically, the EGR system requires very little vacuum to operate and the modulator only passes part of the vacuum on to the actual EGR valve.

The distributor needs about 5 inches Hg to open full advance. I Checked mine and it pulls 15-20 Hg at that port with the throttle open. With the BVSV disconnected and the canister hooked up in it's place, I was pulling about 8-10 Hg from the end of the distributors vacuum hose at high rpm open throttle. That's enough to pull the distributor advance. You can further increase the vacuum to the distributor by placing a small diameter restrictor in the cannisters vacuum line.

They all use ported vacuum and they all pull it from the throat just above the throttle plate in the main barrel. The only issue I can see is that you are pulling from the charcoal canister, so you are drawing fuel vapor from the tank through your vacuum lines, and some of it may travel upstream to the EGR or the Distributor. Probably not enough to be concerned about, but enough to not design it like that.