2008 Cayman Fuel Fill Charcoal Canister

I have a 2008 Cayman base with the dreaded fuel fill vent charcoal canister problem where when filling the gas tank, the pump constantly shuts down over and over and it takes about 10 minutes to put a half tank of gas in the car. Took it to my local Indy shop and they said my Charcoal Canister was plugged and super heavy meaning it is bad and that the part number 99720122104 is no longer made. I checked myself and every parts supplier is listing these as discontinued and the only ones for sale are used on Ebay. Does anyone know of the replacement part for these or if there is a work around to eliminate this completely and to code it so any fault lights don't come on? I live in the USA. Odd that Porsche would stop making this part is this is a somewhat common issue on many 987 Caymans .

I just put your vehicle info into Pelicans website and it seems they may have the part. Good luck.

Tried that but their site comes up with the 997-201-221-06 canister which is wrong. I need the 997-201-221-04 part number.

Just contacted the dealership. Part 997-201-221-04 has been discontinued and has not been superseded. Only avenues are Ebay or Porsche scrap yards or deal with issue and spend 10 minutes putting in a 1/4 tank of gas due to venting issue. Dealership said numerous inquiries have been made about this part and all are sent to Porsche Germany so if enough inquiries are made Porsche may start sourcing these units again down the road but for me that doesn't help. Wish you could just eliminate the unit altogether and code it out, so no faults are thrown.

Oh crap, its hard to imagine them just abandoning a critical part of the emissions system. In most states that have an annual safety/emissions testing it would fail and the vehicle could not be registered/renewed.

I agree. The parts guy immediately knew about the exact part number and part that I was referencing. He shared the same sentiments as you. Very hard to imagine that they would discontinue this part but they have.

Just poking around I see on Sunset that 996-201-221-03 fits a base 08 Boxster , but not Cayman . That seems wrong - should be identical. I wonder if this is just some screw-up with Porsche 's part system. Vapor Canister - Porsche (996-201-221-03)

No that will not work. That model along with the 997-201-221-06 part number is tall and skinny. The 997-201-221-04 is like a box.

Hello, I believe you can use the following internal part to service your original canister. 997-201-501-01 Vapor Canister Filter for Carbon Canister Below is a picture I found on R3nnlist Paul

Yes, but unfortunately the problem with these canisters or the ones that go bad is the charcoal that fills all of the compartments outside of this paper filter area gets solidified and turns to pretty much stone and is next to impossible to chip out enough of it to get proper flow to stop the venting issue. Regards

I snagged a used but tested on off of Ebay with somewhat low miles for cheap. Hopefully this will give me years of no vent issues seeing that I only drive the Cayman a few months out of the year here in Michigan.

Has anyone noticed a correlation between topping off the tank and failures of these canisters? The charcoal only turns to stone when it's repeatedly soaked by liquid fuel. On BMW motorcycles (I know - but it is an opposed engine) they had ones that would fail due to gasoline overfill - fill the tank cold, then park it in a hot garage, and the expanded fuel was pushed into the charcoal filter. The answer there was to eliminate the canister and plumb the vacuum plumbing like it was on euro bikes. I wonder if the same charcoal canister/filter is used world wide on Porsches, or only on US Porsches? If only on US Porsches, It might be possible to code the car as a euro car and eliminate the canister. And don't overfill the fuel. NJ gas stations - where uniformed attendants with years of specialized training pump you fuel for you - and the driver isn't allowed to pump their own fuel - the attendants always used to top off the tank - usually filling the filter tube right up to the top, and causing the charcoal canisters to get plugged up. Someone must have changed their training now since they no longer do this. BTW - at one time - Porsche had a retrofit sleeve that fit into the fuel intake to provide a "to-air" vent of the tank as you fill it. If you have fume capture nozzles like the ones mandated in NJ and most states now - it really doesn't vent "to-air" - it vents into the gas stations vapor recovery system and getting rid of it is their problem. I bought that sleeve once figuring I'd be prepared, but I am fairly clueless on where I put it. So far 78,000 miles and it hasn't failed yet.

Is the charcoal media in the canister a solid block to start with from the factory, or small granules of activated charcoal that have turned into a block? If the latter, I'd open it up and replace the depleted block with granules which can be had from many sources inexpensively. If appropriate to maintain functionality.

This is a known issue and it’s frustrating Porsche discontinued 99720122104. No official replacement exists, so most either source a clean used canister or retrofit one from a 997.2 / 987.2 . Bypassing it is possible, but it risks CELs unless you tune out emissions codes. Some have had luck cleaning/re-routing vent lines to temporarily relieve the issue. Keep an eye on reputable dismantlers for low-mileage used parts. Would be great if the aftermarket stepped in with a reliable solution.