Gas Filler Neck

[smallfry]

How important is that metal flap/disk on the gas filler neck cause it's missing on my 4runner?

 

[JohnsD90]

How important is that metal flap/disk on the gas filler neck cause it's missing on my 4runner?

I wouldnt worry about it unless you leave the cap off often, my rover has no flap at all, its just a big hole hole.

 

[Socco]

How important is that metal flap/disk on the gas filler neck cause it's missing on my 4runner?

Not incredibly. It helps to minimize fuel evaporation and keep debris out. It wont hurt the fuel pump as it cant get past the sock. In my neck of the woods, there was a time where they would check for the flap as part of emissions testing, but not anymore. For the amount of work it takes to replace it, I personally wouldn't bother.