The invention relates to an in-tank evaporative emission control system. The evaporative emission control system includes a fuel vapor adsorption unit in physical contact with a heat generator inside a fuel tank. The heat generator can be a fuel pump that heats the adsorption unit during a purge cycle, thereby increasing the rate of desorption of captured fuel vapor during the purge cycle. The fuel vapor adsorption unit and/or an additional fuel vapor adsorption unit may be located inside the tank volume proximate a tank inlet opening so that incoming fuel can cool the adsorption unit(s) during a refueling event, thereby increasing the adsorption efficiency of the adsorption unit(s) during the refueling event.