How to remove charcoal canister and not get CEL?

[ike84]

Originally Posted by akbaradeli

This is just forward of the gas tank and has several plastic fuel-line connections running into it. Disconnect those lines using the flathead screwdriver. Unbolt the charcoal canister from the frame using a 3/8-inch ratchet and socket. Slide the canister out of the bracket and remove it from the vehicle.

Akbar, have you done this? The real question is what to do with the disconnected hoses.

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[rezanourai]

Sorry for the big delay guys, I finally got a used motor swapped in for the one I blew. Did the IMS & deep sump kit right out the gate this time so fingers crossed this one lasts longer

Back to the EVAP now, I took the fender off and did a bit of poking around to come up with a plan, and then will try to sort this out next month. Here's what I think I know so far:

1. There are 3 hoses to the top of my charcoal canister. 2 larger diameter (looks like maybe 1/2" or 5/8"), and one smaller diameter (looks like 3/8").

2. One of the larger ones goes over to the valve housing (the thing that has 2 large tubes coming in the front, and one smaller (3/8"?) coming out the side, with 2 wires connected in the back to control the individual (purge?) valves inside

3. the 3/8" side hose coming out of the valve housing seems to be the one that goes to the rear bumper. I had the rear bumper off and asked my wife to listen & watch as I blew compressed air into this and she confirmed she saw a puff of dust & noise come out when blowing into this tube.

4. the 2 larger hoses in the valve housing are to the canister (as mentioned in #2 above) and to the fuel filler cup (not the neck, but a hole directly into the cup underneath the flip open lid). This leads me to believe that this valve housing is likely both "eject" valves to purge out air to the atomosphere. My guess is that normally the one to the fuel cup is open so any built up fumes there vent out to the rear of the car, and when the canister is full & intake isn't doing it's thing, maybe it closes that one & opens the one from the canister to eject that to rear? Not sure yet on this...

5. This leaves 2 hoses (1 larger and 1 smaller) on the canister. Using the completely not trust-worthy "sniff" test of these two, it appears the thicker one has a light fuel vapor smell coming from it, and the smaller does not. My guess is larger is teh fuel tank vent, and the smaller is the path back to the intake

6. There are also 2 smaller hoses connected to the fuel filler neck itself. I believe these are for venting out air from the tank while filling fuel so that the gas can fit in the tank (displacing air), but I am not certain exactly how these two work. There is also a wire to the fuel filler neck, so this has some electronic control or valve?

Anyways, I'm trying to find a bit more info on the fuel filler neck ones, and verify the other data I have and then going to try to tackle this. Maybe something like: plug the intake hose, use a Y-fitting to connect the fuel tank vent & fuel cup vent to the rear bumper hose, with a simple rollover valve inline of the fuel tank one, and maybe a pressure activated valve on the exit side towards rear bumper end to prevent fumes from just filling up my garage unless enough have built up. But I'm not yet certain on this yet.

Here are some pictures I took:

[rezanourai]

Oh, forgot one more piece of important info which I think supports the rest of the theory. One of the hoses to the filler neck, which has the blue diaphram looking thing on it, just connects back into the main large tube coming from inside car to the evap canister (which I'm suspecting is the tank vent). This means as fumes are venting from the tank, they can either go to the charcoal canister, or if the blue diaphram thingie is open & the valve on the filler neck is open, it can vent into the neck to allow gas to go in.

This video seems to confirm that the valve is activated by just inserting the gas pump nozzle, not electronically controlled. Also seems to confirm the one end (through blue thing) to the tank and the other end goes to charcoal canister (I didn't see that, but maybe it goes further down and connects, will need to recheck)
https://www.youtube.com/watch?v=zulI06TPBVc

And actually, the more I think about it.... if the vent to the gas filler cup while refueling is just there to let air out of the tank when gas is going in, and this is connected to the same hose coming out of the tank as the normal line to the canister, then when I vent that out to atomosphere, won't that "automatically" solve the venting while fueling issue? In other words, can I just get rid of the hoses & fuel filler neck valve altogether? I really wish there was more information on the web about this stuff from people who've done this before. It's like the one area of the boxster that doesn't seem to be heavily covered!

[trygve]

I think you are on the right track in general -- wish I had concrete info and could recall, but I am pretty certain that I connected the tank vent line to that line that feeds out the tail of the car. You want the vent fumes, however minor they may be, to go out the back of the car rather than into the filler area where you may smell them wafting into the cabin while driving and make you wonder if there's a leak!

[ike84]

Originally Posted by rezanourai

Oh, forgot one more piece of important info which I think supports the rest of the theory. One of the hoses to the filler neck, which has the blue diaphram looking thing on it, just connects back into the main large tube coming from inside car to the evap canister (which I'm suspecting is the tank vent). This means as fumes are venting from the tank, they can either go to the charcoal canister, or if the blue diaphram thingie is open & the valve on the filler neck is open, it can vent into the neck to allow gas to go in.

This video seems to confirm that the valve is activated by just inserting the gas pump nozzle, not electronically controlled. Also seems to confirm the one end (through blue thing) to the tank and the other end goes to charcoal canister (I didn't see that, but maybe it goes further down and connects, will need to recheck)
https://www.youtube.com/watch?v=zulI06TPBVc

And actually, the more I think about it.... if the vent to the gas filler cup while refueling is just there to let air out of the tank when gas is going in, and this is connected to the same hose coming out of the tank as the normal line to the canister, then when I vent that out to atomosphere, won't that "automatically" solve the venting while fueling issue? In other words, can I just get rid of the hoses & fuel filler neck valve altogether? I really wish there was more information on the web about this stuff from people who've done this before. It's like the one area of the boxster that doesn't seem to be heavily covered!

I also think you're on the right path here. If you vent the fill neck to atmosphere you should be fine.. in your case, anything you vent to atmosphere should probably have a rollover check valve in front of it, just in case. It might also be neat to write in a controllable valve that you can close for storage. Also, make sure you block of the line going from the purge valves back to the intake so you don't get a vacuum leak. I'll be curious to see if this causes the cel to go on... Keep us posted!

Happy to see the car back together, btw. If you get a minute, will you share how you removed the fender?

[rezanourai]

I'll take some pictures and post something proper up next time I take the fender off, but it basically boils down to:

1. lift car, remove wheel
2. remove wheel liner (couple of those push-tabs and some plastic 10mm nuts)
3. disconnect and remove the charcoal canister (this allows access to the 3 bolts holding the fender on near door hinge)
4. reach up and unplug the wire to the gas filler door lock mechanism (I no longer have this lock mechanism or wiring on my car, but other cars will have it)
5. open the fuel filler door and remove the 10mm bolt in there (not 100% sure this one was required or not)
6. from the backside of the fuel filler cup, press on the black plastic tabs that hold the plastic cup to the fender-portion of the fuel filler area
7. remove the headlight. The headlight tray comes out as part of the fender, so make sure you unplug the wiring & vent hose for the headlight

8. now time to unbolt the fender from the car... start with all the torx screws up top (with frunk lid open) between fender & frunk. The last one is on a piece of the fender that's tucked in under the hinge for the frunk lid.
9. open the 3 that are exposed behind the charcoal canister (all 10mm) top middle and bottom back near the door hinge area. The top one is a bit of a pain to reach, I needed a couple of extensions connected together to get my socket up there.
10. I found that loosening the bolts (but not fully opening them!) holding the frunk hinge to the frunk was necessary to gently rock the fender loose from under it.

NOTE: I have removed a bunch of wiring, trim, etc... from this car, so there might be additional steps required for other cars, but I don't think so. I think that's about it above.

[ike84]

Originally Posted by rezanourai

I'll take some pictures and post something proper up next time I take the fender off, but it basically boils down to:



1. lift car, remove wheel

2. remove wheel liner (couple of those push-tabs and some plastic 10mm nuts)

3. disconnect and remove the charcoal canister (this allows access to the 3 bolts holding the fender on near door hinge)

4. reach up and unplug the wire to the gas filler door lock mechanism (I no longer have this lock mechanism or wiring on my car, but other cars will have it)

5. open the fuel filler door and remove the 10mm bolt in there (not 100% sure this one was required or not)

6. from the backside of the fuel filler cup, press on the black plastic tabs that hold the plastic cup to the fender-portion of the fuel filler area

7. remove the headlight. The headlight tray comes out as part of the fender, so make sure you unplug the wiring & vent hose for the headlight



8. now time to unbolt the fender from the car... start with all the torx screws up top (with frunk lid open) between fender & frunk. The last one is on a piece of the fender that's tucked in under the hinge for the frunk lid.

9. open the 3 that are exposed behind the charcoal canister (all 10mm) top middle and bottom back near the door hinge area. The top one is a bit of a pain to reach, I needed a couple of extensions connected together to get my socket up there.

10. I found that loosening the bolts (but not fully opening them!) holding the frunk hinge to the frunk was necessary to gently rock the fender loose from under it.



NOTE: I have removed a bunch of wiring, trim, etc... from this car, so there might be additional steps required for other cars, but I don't think so. I think that's about it above.

Thanks a bunch man! That's a great instructional, much appreciated.

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