Abstract
This paper discusses an evaporative emissions control system which significantly reduces diurnal evaporative emissions in walk behind lawnmower engines equipped with float carburetors. The system also maintains engine startability, run quality, and a simplistic user interface. The system consists of low-permeation fuel line and a multi-layer fuel tank using an EVOH barrier as well as a carbon canister integrated in the lawnmower´s push-handle and an Automatic Bowl Drain System (ABDS). A prototype of the system resulted in a 90% reduction in diurnal evaporative emissions when compared to a pre-regulation walk behind lawnmower using the CARB TP-902 sealed housing for evaporative determination test. This paper demonstrates a practical solution to reduce diurnal evaporative emissions and hydrocarbon running losses below the level emitted from a state of the art, float carbureted, walk behind lawnmower engine.
Keywords: Pollution, Diurnal Evaporative Emissions, Fuel Permeation, Lawnmower, Small Engine