Failed smog - EVAP test

[Brob]

Looking for advice, after a number of months working on my 81 320i to get it road worthy I attempted to pass smog today in Southern Cal. Unfortunately it did not pass due to a failed evap test. Is the solution just changing out the charcoal canister or is there something more U should be looking at?
Thanks for any input
Bruce

[320iAman]

No, It could be the gas cap wont hold vacuum( rubber seal piece is gone or cracked) or the top hose that connects the left and right gas tanks and any hoses in the evaporation system,, ask the tech what failed,, they started to due a 2 psi test on evaporation system- if the top hose that connects left and right gas tanks is cracked it wont hold a vacuum of 2 psi.. I changed out my top hose plus all the hoses in the evaporation- no problem, I also installed a new BMW carbon canister before that.

Randy

[Brob]

Thanks Randy, I was planning to drop the fuel tanks to replace the vent hoses at some point, the charcoal canister is probably original so I thought is start there. Thanks for your help

[320iAman]

Sure, When I took down the driver side left tank, I found the cloth hose linking the left and right gas tanks was cracked, you'll see left and right tanks are connected by two hose pieces thru a "Y" connector-open the inspection plate under the back seat passenger side tank-where the in tank fuel pump, ect is accessed, the other leg of the Y connector has cloth hose as well that go to the expansion tank in the trunk and then there is a few more cloth hoses from there that need to renewed. It will keep you busy for a while.

Randy

[Brob]

When I replaced the in tank fuel pump I could see the old cloth vent hose was still there. I replaced all of the fuel lines but left the vent hoses and the main hose connecting the two tanks for later. I didn't realize it could affect my smog test or I would have done it sooner. I Learn something new about this car every day

[Abazal]

I failed EVAP a while back and ended up replacing all the vent hoses and dropping the tanks to get those last few tricky houses. You should know if your gas cap failed because they should test the cap itself. They usually pinch off the charcoal canister line so I don’t think that could be an issue as well.
Dropping the tanks and doing the lines takes maybe half a day with a buddy.
Hope this helps


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[amarino]

I almost failed on the gas cap earlier this year. The tech let me into the shop and showed me the machine and test process. Luckily everything else was good so he let me run to the auto parts store to buy a new one and come back to show him. Then he gave my papers back and submitted it.

Pic of what would fail:
IMG_20190831_094630.jpg

[Brob]

Thanks Amarino, good to know about pinching off the charcoal canister, I saw them use pincher clams but that didn't register with me when they did it. I'm sourcing all the hoses now. The one that kills me is the hose from the filler to the tank. Approx $75 domestically and $27 from Walloth nesch.
the guy doing the inspection used his own cap to pressurize the tank so it's not my filler cap.
Thanks again for everyone's help

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Abazal thanks for your info, I appreciate it

[amarino]

They should / do also remove the gas cap and test it individually, like so https://www.youtube.com/watch?v=fmH39CSye10

But it also has a separate line item on the Test Results to call out if it was just that. But worth looking at to see if the seal looks dried or cracked.

[Abazal]

I got all my hoses from Napa auto parts. No need to go through online sources.


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[Brob]

The only hoses I'm concerned about are the one that connects the filler tube to the tank and the hose that goes between the 2 tanks. All the others are pretty easy

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The only hoses I'm concerned about are the one that connects the filler tube to the tank and the hose that goes between the 2 tanks. All the others are pretty easy

[mxl556]

I'd make sure to get metric sized hoses as it makes job much easier than getting standard hoses to fit. I have done that job twice and second time used metric hoses, made it easy and did not break any plastic connectors/junctions. There is no need to drain fuel and drop tanks completely, lowering some is enough.

[Somjuan]

I replaced the y fitting entirely with a brass one, and like Abazal it was all the nicest fuel rated-hoses I could get from ACE. Passed smog for three years like that, and probably would have continued passing like that if my head gasket hadn’t popped.

[Brob]

Thanks again everyone, great help. I think at this point I'm going to drop the tanks completely and clean them up. i believe they are in good condition but I might as well we'll I'm at it