Check Fuel Cap light on

I’m trying to get 2001 ford focus zx3 to pass smog. Well, the mechanical does, the ‘emissions’ reads are all passing…its just this &*% check fuel cap light wont’ go away! I changed the cap, it fits and is right part. and now? today? the check engine light comes on and as you know won’t pass the monitor reading test. I can’t afford to keep having it smog tested if the light pops on 10 min before the test! What is the procedure for checking the 'canister and what is the schematic for the evap system so I can follow and check for cracks lose, etc…

You have a leak somewhere in the Evaporative Emissions syetm. The best wya to find it is with a smoke test. That’s a test where smoke is pumped into the system and leaks out where he leak is.

The first test is to pull a vacuum in the system and see if it holds. There is a test port for this under the hood protected with a green cap. Next, a smoke test is performed. Smoke is pumped into the evap system and a visual inspection attempts to locate evidence of smoke leaking out of the system.