A fuel tank cap includes a casing; a main chamber disposed in the casing; a vapor vent channel disposed in the casing and communicating with the main chamber; annular partition walls disposed in the main chamber and configured to divide the main chamber into troughs, each partition wall including a cut so that the troughs are capable of communicating with each other via the cut; and activated carbon filled in the troughs. The vapor vent channel includes the cuts and the troughs. The activated carbon captures fuel vapors and absorbs VOCs in the fuel vapors when the fuel vapors pass through the vapor vent channel. The invention eliminates the low efficiency problem of capturing the harmful VOCs of the fuel vapors by the conventional activated carbon canister.

Filler cap for fuel tank which can further prevent environmental pollution without releasing harmful gas evaporated from fuel in fuel tank and can improve fuel efficiency is provided. When vaporized gas is generated in fuel tank, inner pressure of fuel tank is increased to pressure for deformation strength prescribed to valve body or more, a central part of valve body enters into third space thereby causing deformation so to shorten outer diameter of valve body to form wrinkles, and in peripheral part of valve body are formed a portion contacting to pivot of cylinder main body when deforming and concave portion not contacting thereto, second space and third space are connected via space of this concave portion and air passage channel formed in wall surface forming second space to release excessive pressure to outside fuel tank thereby bringing pressure inside fuel tank to lower than the pressure for deformation strength.

A fuel cap is described as having a top assembly and a bottom assembly slidably engaged with, and concentric to, the top assembly. The top assembly having a cap cover and a cylindrical cap body concentric with and protruding substantially perpendicularly from, an underside surface of the cap cover. The bottom assembly having a vacuum valve operatively coupled with a valve body. A wire-form keeper may slidably secure the bottom assembly to the top assembly. A pressure spring may impart a force that biases said bottom assembly away from said top assembly.

A vent having a vent housing defining a mounting structure, a first opening between a first end and a second end of the vent housing, a first airflow pathway from the first opening, a second airflow pathway from a second opening, and a draining pathway from the first airflow pathway through the first end of the vent housing. The first airflow pathway has a first segment and a second segment extending in opposite axial directions. An inlet relief valve and an outlet relief valve are arranged in parallel between the first and second airflow pathways. The inlet relief valve opens upon exceeding a first threshold pressure differential of the second relative to the first airflow pathway. The outlet relief valve opens upon exceeding a second pressure differential of the first relative to the second airflow pathway. A filter assembly is disposed in the vent housing across the second airflow pathway.