How to remove charcoal canister and not get CEL?

[ike84]

No, don't delete the purge valve. I don't know this for for sure but i think it will be far too much trouble to do so than what it's worth. just delete the canister and route the vent lines directly to the purge valve.

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[rezanourai]

Originally Posted by ike84

No, don't delete the purge valve. I don't know this for for sure but i think it will be far too much trouble to do so than what it's worth. just delete the canister and route the vent lines directly to the purge valve.

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Hmm, ok. I'll need to splice back in some of that wiring (I had cut out all the wiring related to EVAP) to get the purge valve to work again. I'm assuming that the default state of the valve if no power on it is closed?

I guess what I still don't understand is when the purge valve is closed, how does air get in or out (ie, what prevents it from being a closed loop system?).

[ike84]

Originally Posted by rezanourai

Hmm, ok. I'll need to splice back in some of that wiring (I had cut out all the wiring related to EVAP) to get the purge valve to work again. I'm assuming that the default state of the valve if no power on it is closed?



I guess what I still don't understand is when the purge valve is closed, how does air get in or out (ie, what prevents it from being a closed loop system?).

I just saw your build thread. I didn't realize your building a racer.

You can probably get away with removing the whole thing but you will likely get a CEL. A lot of racers will though, just check your codes prerace. If it's that big of a deal you may be able to delete it with piwis but I don't know for sure. Also, your garage will probably smell a bit like gasoline. As long as your garage isn't too hot it probably won't be horrendous but that's hard to say.

Don't block off the tank vent or filter neck vent lines, you'll regret that. If you delete the purge valve, I would block off the tube going back to the intake or else you'll likely have a vacuum leak.

I don't know the answer to your last question. There may be a valve built into the charcoal canister as a burp valve? It may just act as a resivoir and not actually vent. Not sure about though.

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[ike84]

Originally Posted by rezanourai

Hmm, ok. I'll need to splice back in some of that wiring (I had cut out all the wiring related to EVAP) to get the purge valve to work again. I'm assuming that the default state of the valve if no power on it is closed?



I guess what I still don't understand is when the purge valve is closed, how does air get in or out (ie, what prevents it from being a closed loop system?).

How is this going for you so far? Any progress?

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[rezanourai]

Originally Posted by ike84

How is this going for you so far? Any progress?

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Unfortunately blew the motor at the track a few weeks ago, so have been focused on sourcing and swapping motor lately, will finish the canister stuff after that. My plan was to use a combination of a rollover check valve and a light pressure opened valve to vent to atmo but not stink up garage, and avoid leaking fuel I'm the event of (hopefully never) rollover

[ike84]

Damn, I just realized that was your post about the blown motor. Sorry again to hear about it.

You've got an interesting idea though about those check valves, I never even thought about a rollover check valve.

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[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.

[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?