Complete In-Line Fuel Filter (33629) by WIX®. One Off-Set Line. The fuel filter is often the forgotten filter. Yet the fuel put into diesel and off-road equipment, more often than not, contains contaminants such as dirt, rust, scale and water. These impurities can plug fuel injectors and carburetors, resulting in engine malfunction or deterioration. These contaminants often originate from dirty and rusty storage tanks, and as the vehicle ages, from corrosion within the fuel system components. All the more reason to invest in high-quality WIX fuel filters and to maintain them at recommended intervals.