Gas tank top off amount?

[BlackCloud]

I believe that is the charcoal canister (EVAP vent) everyone has been talking about. Someone with more knowledge please correct me if I'm wrong. But, overfilling fuel into the neck causes damage to the charcoal (saturation) and results in CELs. You will get fuel odors and the seeping carcinogens from it as well.

Well what kind of damage could result? If I fill up to the tippy top and drive off, it's only a matter of minutes before I use enough fuel to drain the fuel out of the neck. I don't think many people fill up and then park across the street for 3 days.

 

[blaniac22]

doubtful. the 23ish manufacturer number would be well below the vent hose, which is somewhere on the top of the tank. below the fill neck.

EVAP Evaporative Emission Control System

If you continually overfill it to the point where fuel gets down the vent tube and into the canister you run the risk of saturating the charcoal inside. There are systems in place to prevent the fuel from getting to the canister, but why risk it? It’s a matter of shortening its life, not an instant failure and you will only know something is wrong when you get the CEL. For that reason, topping off to the top of the filler neck is not recommended.

I haven’t had to replace one on the 4Runner, but I did in a ‘99 Camry. It cost around $400 and I did the work myself.

On my 4runner, the EVAP canister runs around $700 for the part alone.