Charcoal canister- how does it work

[gclark]

I have a 72 with 350 cid Quadrajet. It has the original evap canister mounted next to the battery.

The canister has a valve on top with 3 hose connections. It also has a filter on the bottom.

The three hose connections are:
Canister to fuel tank
Canister to PCV and carburetor manifold vacuum
Canister to carburetor ported vacuum

Questions: what is the function of the valve on top of the canister? Why is the ported vacuum line necessary?

Thanks in advance.

[Gromit]

http://www.ifsja.org/forums/vb/showthread.php?t=174213

Here you go - was just looking at this myself.. trying to sort out a fuel supply problem.

There is a Tpub about this as well from the military International Harvester tech

http://firetrucksandequipment.tpub.c...-14P-1_788.htm

[Gromit]

Sorry - I neglected to credit 71shortbed402 for that excellent link to the FJ vapor canister info:

http://67-72chevytrucks.com/vboard/s...d.php?t=686040

He - (71shortbed402) is the one to thank - it was an excellent find and I only knew of it due to his efforts on behalf of the board..

[gclark]

Thanks that answered my questions!

Any idea where i can find correct replacements for the pcv line, tee, vacuum line, and evap line?

[gclark]

Thanks for pointing this out. I had read 71shortbed402's post but did not notice the link until you pointed it out. Very helpful.

I have not found a source for the rubber lines associated with this canister. If anyone knows of a source i would appreciate a nudge in that direction.

[Gromit]

Fuel Supply lines for the V-8 Chevys are 3/8" - in my neighborhood I just go to Oreilly or Autozone for hose of that size - unless I'm feeling generous and like paying 1-1/2 times more then I can go to CarQuest or Napa or even more local types.

As far as fittings really it was so rare and so state by state for EEC stuff in 1970 that you are better off just fabbing the fittings that you need

The EVAP lines are 5/16ths and same ting - Oreilly / Autozone are best unless you can get free shipping from somewhere else somehow

Only problem is I notice my local stores don't pay much attention to their bulk hose stock - so even though they buy a 100' roll of the stuff it is beyond them to plan sufficiently in advance for their stockouts..Doh!

So 1 out of 2 they will be all out when you ask...Homer Simpson must be in charge I think..

Might as well pop a Duff beer with him and hope for the best

[71CHEVYSHORTBED402]

I've researched them pretty extensively:


http://67-72chevytrucks.com/vboard/s...d.php?t=686040
http://67-72chevytrucks.com/vboard/s...d.php?t=569115
http://67-72chevytrucks.com/vboard/s...d.php?t=682939
http://67-72chevytrucks.com/vboard/s...d.php?t=690745

Page 34 of this: Click on the icon that reads: Chevelle SS Restoration Guide, 1964-1972
https://books.google.com/books?id=Cc...nister&f=false


Original Canisters:
7028129 Early 1971ish.
7030541 Later 1971ish. Mine has this.

GM Replacement: 7030605

Works: 17063011. "Carb Bowl" sealed on at least some of these canisters.

Other:
7026014: Filter filler pad.

729150: Standard Canister Filter Element: May work for inside as well, because it's stiff.

7021739: Filter filler pad with bottom NOTE: Some canisters may have come with the bottom "funnel cover" and some without. Either way the bottom attaches to the canister. The bottom filter lays at the bottom of the canister or inside the "funnel cover". Found these instructions for similar.........."Install new filter assembly by aligning the slot in the cross bars with the single crossbar on the bottom of canister, and snap into place".

AF-450: Another Filter filler pad with bottom funnel.

Unknown Part No: Inside "foam rubber" filter elements, top and bottom.


Only thing I haven't done yet is rebuild one. That and answer the question, is that other line to my fuel pump for the tank expansion? I'm guessing so, meaning I'll need a new fuel pump with the restore. See, I pulled my canister off with the rebuild a long time ago, which was led by my buddy. I forget, and by no means am knowledgeable about emissions/carb.


Incidentally, if anyone wanted to earn a buck, seems an OER vapor canister for our trucks is in order. Not just our trucks, but LOTS of vintage GMs. Many used the same canister.

[Rich72C10]

Thanks for this posting and its information!

My canister was plugged up - at the fitting where the spring & rubber membrane are at. My brother was debugging some fuel things and it lead him to this canister. He ended up just leaving the connections off after he gave up on trying to figure it out.

Sadly, my brother put the top, spring, retainer, and membrane in a bag and the nipple on the top lid got broken off while bouncing around in the box of bigger parts.... grrr. Though to be honest whatever is plugged up in there is not coming out.

Luckily I found one on eBay listed as 1973 Chevrolet Corvette Fuel Vapor Canister (CHARCOAL CANISTER) GM7030605. Was a little pricey but listed as in good shape/etc. So between it and mine - I could rebuild it if I need to.