Isn’t my filter supposed to keep my fuel system clean?

Written by Capt. Jeff Werner

Filtration simply cannot and will not do that. At best, filters, separators and centrifuges remove debris suspended in fuel before fuel reaches the engine. Stopping, preventing or reversing the process of fuel breakdown is a completely different matter that can be addressed by and resolved with a combination of magnetic and chemical fuel conditioning.

It is not very likely that filtration (either an external filter or a filter on the engine), will remove the sludge coating from the walls and baffles of your storage tank and the use of biocides will almost always aggravate the situation. Filtration has no effect on the fuel break down processes whatsoever.

Filters are primarily designed to remove inorganic debris from the fluid stream and they become clogged with organic debris, resulting from fuel degradation. The water separator is designed to remove free water. However, a separator and filter combination or a centrifuge cannot remove emulsified water. But a filter and water separator combination is essential in any diesel application. Most of the debris you see on the filter elements, the stuff that clogs your filters, is the result of the fuel having begun to form solids.

Capt. Jeff Werner, a Licensed USCG Master, has sailed professionally throughout the world. ┬áHe is also the Diesel Doctor, helping to keep your boat’s fuel clean and bright.

If you have additional questions for Capt. Jeff Werner, please email him