speedkar9

Here's how the EVAP system works in your car to ventilate harmful gasoline vapors from escaping into the atmosphere:






I took apart the entire EVAP system to examine how it works on an Infiniti G35.



The most visible part of the EVAP system is the fuel filler neck:




But looking underneath, the gas tank, vacuum and filler tubes and EVAP canister comprise the majority of the system, seen here with the rear subframe removed:





Here's the EVAP canister, behind the rear right wheel area:






Inside the vehicle, the fuel pump (right) and fuel sending unit (left) are accessible underneath the rear seat:



Here's the gas tank dropped out:



Here's the entire EVAP system removed from the vehicle, from the gas tank and lines, the filler neck and tube to the charcoal canister and vacuum lines.




Here's the charcoal canister. The left most line is the vent, the right most is the purge line that goes to the air intake in the front of the vehicle, and the middle one leads from the gas tank.




Before cutting open the gas tank, I pumped out all the gasoline.




Fuel pump and sending unit removed:





I manually pumped another 3L of fuel after the fuel pump couldn't pump anymore.


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I filled the tank with water and cut it open. Here you can see the baffles and the valving at the top of the tank:



A closer look at where the vent line and evap canister line connect to the gas tank. The smaller device (top) is the vapour cut off, and the larger device below is the fuel liquid separator, which prevents liquid gasoline from entering the charcoal canister.



Here's the tank cut open:



The float inside the liquid separator rises and shuts off the exit for any vapour that vents during refuelling.




Here's the charcoal canister chopped open. It's responsible for absorbing gasoline vapours and acts like a holding tank before it can be purged to the engine.






The gas cap is essential to holding pressure in the system during a self check. It features a spring loaded pressure relief valve as a safety in case pressure builds too much, it can vent.




The vent solenoid is simply an on/off air switch. When cut open, it is simply a coil that is energized to move a plunger in and out:





And that's all the main components of the EVAP system and how it works! Next time I'll open up the fuel pump and sending unit and go into deeper detail.




Enjoy