fuel tank nyo sir baka po madumi na.... nakakasip ng dirty fuel kaya pag 1/4 tank nalang dirty fuel na ang nasusunog.... check nyo po fuel filter.... or replace it with a new one, then after 2 weeks or 350kms. inspect it again kung madumi na agad kahit kunti or dark na color agad ng fuel, it means its time to pull down your fuel tank for cleaning....