986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - How to remove charcoal canister and not get CEL?

rezanourai · 06-28-2021, 07:37 PM

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:

06-28-2021, 07:37 PM	#59
rezanourai Registered User Join Date: Oct 2020 Location: California Posts: 76	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: