This paper mainly concentrates on pre-combustion process to increase fuel burning efficiency, decreases fuel consumption and to reduce exhaust pollutants. In the experiment comprises the use of permanent magnets (Neodymium) with different intensities (4000 and 8000 gauss) in the fuel flow line before the carburetor. Hydro carbon fuels are initially in Para state and cluster structure has more intermolecular force of attraction. So, it has fewer tendencies to interlock with oxygen molecules. By providing magnetic field these changes to Ortho state which has less intermolecular forces hence fuel particles are finely divided which results better atomization producing a more complete burn. It has been practically tested and for the purpose of comparing results necessitated to conduct the experiment with and without use of magnets. It was found that the percentages of exhaust components (CO2, HC and NO) are decreased by 30.57%, 97% and 36.08% respectively and carbon monoxide (CO) is increased by 30.57% at 8000 gauss. It means internal combustion engines getting maximum energy per specific volume as well as reduces pollutants to lowest possible level.