Warning: a 2007 Civic's EVAP leak took me three days to find
The smoke machine showed nothing, but a pinched hose under the charcoal canister was the culprit. Anyone else have a simple fix that turned into a marathon?
Man, those evap leaks can be pure evil. The smoke test is supposed to be the answer, but sometimes the leak is so small it just won't show. Had a similar thing on an old Accord where the leak was only under a specific vacuum condition. Ended up spraying soapy water on every single line and connector while the system was pressurized. Found a tiny crack in a purge valve nipple you couldn't even see. Sometimes you gotta go back to the simple stuff when the fancy tool lies to you.
Gotta admit, the soapy water trick is a classic for a reason. But calling a smoke machine a "fancy tool that lies" seems a bit strong. In my experience, if the smoke test shows nothing, maybe the leak isn't in the usual spots, or the machine itself needs a check. Those tiny vacuum-only leaks are a special kind of headache, though.
Tbh the soapy water trick is underrated. My buddy's shop still uses it as a final check even after a clean smoke test. Those tiny cracks only show up under pressure.