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Evaporative Emissions small leak detected. Smoke testing the system I get smoke out of the filter for the evaporative emissions pump. This pump connects to the Evap. Canister. I have replaced the evap pump and smoke still comes out the filter. Is there supposed the be some sort of check valve in the canister to keep smoke from coming out the pump. If I block off the filter my flow meter drops to zero.

even a minimum amount of pressure will push past the pump and out of "intake" filter. if that were the leak it wouldn't be a small one. take a good look at the filler neck and the braided hose that v.w, uses is prone to leaking because of dry rot. i would replace those hoses associated with the evap system before i went any further.

According to the flow meter on my smoke machine there is zero flow in the line going to the filler neck. There is nothing in the evap pump to restrict flow once it leaves the canister. Is there supposed to be some sort of check valve built into the evap canister?

from what i read in my shop system it said that if there is smoke coming from vent it's a bad leak detection pump. the only thing that i may suggest you do is to test system through the fuel filler neck since the diagnostic charts that i read all tested from there. i checked the tsb's and such and the majority pointed to the pump. as i mentioned before i really suggest that the braided lines be replaced either before you settle on the pump or before you return it to the customer to eliminate the possibility of a problem in the future.

Replaced lines from canister to tank. Did not fix problem still shows evaporative emissions small leak

what about if you isolate the leak detection pump and then test the system?

having the same problems on my jetta also showing that, thanks for the picture too. I haven't checked it through the fuel filler neck as i am currently busy. would update this soon. thanks!

welcome to the forum. looking forward to hearing from you.