I have not seen a fix for the OEM vapor canister on the 280z posted.  I found a way with new parts to still use the OEM one and have it functional.

Back ground, I have a 77 and have been chasing running issues.  I was focused on vacuum leaks due the a poor idle and erratic performance.  I found the vapor canister as culprit because it never closed the purge line at idle and caused a large vacuum leak. I wanted to keep the canister to not have gas venting from the tank when sitting.   Check out this video on the canister for knowledge and how to test:

 

The vacuum leak was from the line labeled "purge" -  since that goes into the intake and the stock purge valve did not work.  The smaller line on the top labeled "dist vac" comes from a T in the front of the TB and T's also with the distributor vacuum advance (1977 model) - this only gets vacuum when the TB blade is open, which then will open the purge valve to allow the vacuum to purge the fumes accumulated in the canister.   I actually had purchased  another used canister and it still had the same vacuum leak issue.  Instead of chasing used parts or retrofitting from another vehicle, I wanted something new and easily available.  I found an external vent valve to use to solve the issue. This would take place of the original unit on top of the canister.  This along some sealer/gasket maker is all you need (assuming your vacuum lines are in good shape):

$22 on Amazon for the Dorman unit.  This is closed by default until vacuum is applied to the top port (just like OEM)

You add the Dorman unit between the engine and canister:

Then for the top of the old purge valve, under the cap is a rubber diaphragm that seals or allows vacuum to pass (which was inoperative). Remove the internals, seal the top cap with sealer/gasket maker along the edge and use a vacuum cap for port.

Internals under the cap for reference:

Hope this helps others

 

Summary Recap:

1) purchase external purge valve

2) install between canister and intake.  + take dist vac line from the top of the canister purge valve and plug into new external valve

3) Remove top cap on the canister purge valve.  Remove internals, seal the cap back down to the canister and plug the port with a vacuum cap

Edited September 21, 20231 yr by matt90gt
clean up

10 hours ago, matt90gt said:

 I see why the screw as you said was wrong.  The port is in the side of the chamber.  Sealed the top on now .  I cut the 2nd one I had with same issue open:

And from under the top for reference it is on the side , the tank vent is in the center:

Exactly. The only way the port into the side neck of the canister gets down into the carbon part of the can is through the little hole you plugged with a screw.

I suspect that many of the original purge valves built into the cans don't work correctly anymore and I think your use of a new aftermarket purge valve is a cool innovative way to get around that. You just missed the mark a little bit with your original implementation.

10 hours ago, matt90gt said:

Following you now.   Thanks for that tip.

Glad to help.

@matt90gt, A lot of folks search the forum as you well know looking for problem solving clues. By chance did you have an opportunity to go back and edit your strategy for the vacuum canister. Reason I mention is it’s human nature to not read the entire thread. I know I’m guilty of that myself. Thanks for the input and welcome to the forum.

I believe I updated it all.  Let me know if I missed something.

FYI - opening the second unit I had (which was the original 1977 unit) all the internals were in fine shape.  nothing wrong with the filter pads, charcoal or segregation grates (dont know technical term here)

Are you going to try to utilize that one?

1 minute ago, Yarb said:

Are you going to try to utilize that one?

The second vapor canister?  no, I cut it open for my knowledge.

 

wrong thread

Edited September 21, 20231 yr by Dave WM