Vapor Canister Rebuild - A new how to

[nograin]

It may be different. Take a look at the photos my canister above. From the top, looking into purge valve housing you can see the .030" bleed to the cylindrical chamber. Looking inside there is a dot of light coming through both .030" bleed and the .040" passage (which goes up the center of the purge valve housing).

Was yours was arranged differently? Your photo of the inside looks similar, but its hard to be sure. Did they just change materials of the
housing from off white to black, or was there also a design change?

The parts book from cfsja shows the same p/n for 1981-1985 US sold v-8 wags and most J-10s.*
The p/n for the 1986 US sold SJ V-8 is the same as the 1981-85 6 cyl. SJ & J10.
(There is also an additional "restrictor plug" generically listed with the hoses - not clear for what application or which hose lines /ports it fits. Wasn't on my '85 which was pretty factory orignal in this respect when I got it.)

I agree there also a draw on the vapor separator. But that bleed is much much smaller. In terms of area its around a tenth of the main purge. It just isn't flowing very much because the .030" restriction is a much easier path for the air.

Further, when the secondary purge opens, the vapor separator gets exposed to additional manifold vacuum through the far less restrictive .040" passage in the the top of the charcoal canister.

*edit: The number stamped or molded into the top of my vapor canister housing is 3232956 and matches the parts book number for the 81-85 SJ v-8s.

[twmattox]

On mine, that smaller passage (the one located at about 11 o'clock) is sealed. More accurately, it looks like it was never "drilled" open. All of the charcoal canisters I have ever opened have been like this. They aren't clogged...it is solid plastic.

When you place a vacuum on the purge tube, it holds. There is no purging until you place a vacuum on the purge signal (the tube in the lid).

From what I had read in FSMs over the years, this smaller passage was moved from the charcoal canister to the vapor separator.

[nograin]

Whether you realize it or not, you are coming across as if I am misrepresenting this 1985 vapor recovery system. We ought to be colloborating on figuring out why the ones you opened are different than the one I documented here. If you have you have specific years, part numbers or page references this would be helpful.

[twmattox]

Sorry, I am not meaning to contradict believe me, my goal is to help everyone figure these things out. My experience is with '88 and later (for Grand Wagoneer) and '81, '83, '84, '85 (for CJs).

I just went through my parts manuals and pulled this:

8 Cylinder SJ Canister:
81-83 Part Number J 323 2956
84-85 Part Number J 323 2956
86 Part Number J 323 9479
88-90 Part Number J 323 9479

8 Cylinder SJ Liquid Trap:
81-90 Part Number 3300 1586

What I can say is that all of the ones I have ever torn apart are the J 323 9479 canisters (those were what were used in the '81 - '86 CJs).

[twmattox]

The information I have from the '90 FSM:

'90, pages 25-7 through 25-8
YJ Vehicles with 4.2L Engine and SJ Vehicles with 5.9L Engine
The vacuum supply for the canister purge signal is controlled by coolant temperature. A coolant temperature operated (CTO) valve restricts the purge signal vacuu flow to the canister until the engine coolant reaches a predetermined temperature. The CTO used with 4.2L engines opens at 67*-68*C. The CTO used with 5.9L engines opens at 51*-53* C.

Once the CTO valve has opened purge signal vacuum flows through the purge signal to line to the canister. Vacuum from the purge signal opens a one-way valve int eh canister. When the valve is open, fuel vapors stored in the canister are drawn into the engine by intake manifold.

Page 25-9
The evaporative canisters used on vehicles equipped with 4.2L or 5.9L engines have two inlet ports. One port connects to the fuel tank rollover/pressure relief valves and the other connects to the carburetor bowl vent valve.

When the engine is operating and the canister purge function is activated, manifold vacuum draws fresh air through the filter at the bottom of the canister causing the stored vapors to be drawn out of the canister and into the intake manifold along with the crankcase vapors from the PCV outlet. The vapors are then consumed during combustion.

Page 8D-63
Shows the SJ vacuum schematic. This page does NOT indicate orifice diameter (though for many of the other canisters for other models it does).

[twmattox]

Given that you have been working on an '85 and I have been working on an '88. As posted above, they are different part numbers for the canister. So, I did some more digging:

'82 FSM

Page 1J-6:
Vapor Canister
This component is used on all vehicles. The canister is filled wit granules of activated charcoal. Vapor entering the canister is absorbed by the granules.

The cansiter has a staged dual purge feature (fig 1J-8). Two inlets are provided, one for fuel tank vapor and one for carburetor bowl vapor The outlet is connected to an intake manifold vacuum source. The fourth nipple is connected to the carburetor spark port (ported vacuum).

When the engine is operating, fresh air enters through the inlet filter in the bottom of the canister and purges the stored vapor. When the ported vacuum reaches 12 in. Hg, the secondary purge circuit is opened and the canister is purged at a much higher rate.




This supports your diagnosis of two different purge levels in the canister. When looking at the vacuum diagram for this set-up (1982), there is not a vapor separator listed. What I find really interesting is that your '85 does have the vapor separator.

I seem to recall reading (I can't find the source right now) that the air bleed that allowed for low rate purge was moved from the canister to the vapor separator. Which would make sense for the '82 vs '88. Dual purge rate canister without vapor separator vs single purge rate canister with vapor separator.

But, the '85 uses the same canister part number (which presumabely would be dual purge rate) AND a vapor canister that has the same part number as the '88 (3300 1586).

[nograin]

TWMattox - that's awsome! Thanks for looking that all that up and typing it in. I've been through my MR 253 a few times and just can't find a darn thing on the any part of the vapor recovery system. Nor anything in the supplementals, which includes 1986 - which according to our part books definately changed canisters. That said, the MR 253 can be kind of jumbled compared to the earlier FSMs I've seen. Sometimes I find things in places I don't expect and other times, just not to be found...

I've made up some diagrams of how the '85 system worked, but from what you've dug up, its probably not the most common system. Similar, but not the same.

I came up with the same p/n as you for the vapor separator from Figure 25-2800 in the parts book, 3300 1586 Liquid Trap. I need to see if I saved the original one that came on my wag and examine it. The blue one I measured is a new old stock replacement.

I bought the replacement from Kennedy American when I first got the Jeep in 2000. I can't recall if I gave Jeff Kennedy a part number or an application. The part I received had an AMC logo on it and the number EF-8933002029 which I wrote down. It looked just like these on ebay.
All that is long winded way of saying I'm not 100% sure on whether the vapor seperator I have is an exact replacement. Everything else I'm sure is factory stock.

EDIT: ADDITION BELOW

I can't fully explain why the '85 has dual purge canister with a vapor separator. However, I have noticed that vacuum routing was a moving target from '84 through '86. Not only did '85 get a change in EGR control connections from '84, but according to the supps, '86 had an in service fix recommended. So that's 4 changes in 3 years. Looks like a work in progress as they tried to stay ahead of emmissions and maybe also simplify and standardize?

[nograin]

Inside the Vapor Separator

In further response to JeepJeepster's question about the inside of the blue can. Here's a sketch of the insides of the vapor separator.

[nograin]

Canister Operation Diagram - 1985

Below are diagrams of how the charcoal canister works. They show the entire recovery system which should make it easier to understand.

More precisely, these diagrams are for a system using the off-white four port canister marked 3232956, and a vapor separator. If for any reason the images no longer appear here, try going directly the page on my website with this link.

[nograin]

Based on what TWMattox has described, in the black four port canisters (J 323 9479) there is no connection from the manifold vacuum in the purge valve to the center chamber. So for those systems, one could alter the above diagrams by deleting the upward pointing orange arrows in the center chamber. Air either moves toward the fuel tank as fuel is consumed or out into the charcoal and then through the purge valve or the vapor separator.
At least that's my understanding.

[twmattox]

I LOVE those diagrams. Makes understanding these things so much easier!!! Thanks!

[nograin]

Diagrams for 86+ v-8s

Ok. Here's the same diagrams now showing operation for the systems that used canister J 323 9479. This is the all black canister like TWMattox cut apart. It also has four ports on the top but internally it has no idle purge passage. Therefore, purge at idle for recovery systems with this can is done entirely through the vapor separator.

It was used on CJs, 1981-1985 6 cylinder SJs, and to the best of our knowledge (so far) on all SJs from 1986 to at least 1989.

[Strode]

I moved this to the tech archives. Good stuff here, thanks guys.

I need to experiment with mine. I bought a new one per one of the writeups, and it doesn't function as I thought it would. Finding out they are not all designed to operate the same.