My new to me wagon passed every part of CA smog except for the EVAP test. Previous owner said it was the breather hose, idk what or where that is.


According to what Ive found online the entire system consists of a hose running from the gas tank to a rollover valve then the charcoal canister, then from there two lines come out and go into the intake. Ive inspected all these lines (3) and they look pretty good along with the connections. Where else could it be leaking from? Are there any other hoses coming from the gas tank?


If i'm not mistaken they pressurize the fuel system with nitrogen to see if there are any leaks. Could I plug the line going into the charcoal canister somewhere out of site so that the pressure is good for it to pass or can they detect this somehow?

Update: I plugged the hose that comes out the filler tube and goes to the charcoal canister and still failed. Where else could it be leaking? Filler tube itself? where fuel pump is? really dont want to spend 150 to get smoke tested

 

Volvosurf, it could be your filler tube, They are an alloy material , and can get cracks in them from years of careless drivers jamming in the gas hose and manhandling said hose to get it to seal properly in order to pump the fuel. Inspect the inside of the filler pipe carefully...see if there are circumferential cracks up near the fill end. Also, they can become slightly out of round for the same reason I mentioned earlier. When this happens , the "Cap" from the EVAP machine won't fit properly. Sometimes if don't use the right "cap" fitting, it does not make a good seal, also. And, make sure that your fuel cap on your vehicle is a known good cap. The EVAP machine also tests your cap, and will tell the smog tech if your cap is not good. Often, they will sell you a replacement if necessary. The smoke test, though, is a definitive diagnostic tool; even if $150 seems too much.

 

Check the vacuum valve on the canister as well, it could be stuck open. You don't have to take the canister off, if you sure the hose is fine, pull off the larger tube at the throttle, and try blow into it. When the car is off, the valve should be shut and you can not blow air through, the valve only opens when you acceralate (the small tube at the throttle opens the valve with vacuum). Also check the filter at the bottom of the canister(tho it doesn't look like to be causing your problem), clean/change it if its all dirty and pluged. Cheers!