Why Are My Fuel Filters Blocked?

Are blocked filters bugging you? Fuel filter problems are on the increase. We explain why your filters are becoming blocked with slime and sludge and what you can do to stop it.

If you are suffering from the headache of constantly changing blocked filters then be assured, you are not the only one.  As many of you tell us at the exhibitions we attend such as Skipper Expo and Seaworks International, more fishermen and boat owners across all sectors including yachts are      reporting an increase in blocked filters.

The cause is simple to pinpoint and simple to solve.  The main culprit is something known as ‘Diesel Bug’.  This is the collective name for the bacteria, yeasts and moulds that the fuel absorbs from the air.  The bugs attach themselves to the water droplets found in the fuel and sink to the bottom of the tank where they feed from the diesel above.  They double in number every 20 minute- yes, every 20 minutes, living for just 18 hours they secrete waste before dying.  It is the combination of this waste and dead bugs which cause the sludge that is blocking your filters.  

One of the things you are probably now asking is how has water found its way into my fuel tank?  It gets there through condensation, absorption and can even be present when you purchased it.  For a more detailed look at water in fuel read our article How Does Water get into my fuel tank?  However water has found its way into your tank the only way to ensure peace of mind is to remove the water from the fuel.

Using Biocide to Combat Diesel Fuel Contamination

Biocides can most certainly help; however,  as we are all constantly buying new fuel or topping up our tanks this would require us to constantly dose our tanks so the problem won’t go away.  Also consider water is heavier than diesel and will always sink to the bottom of  your tank, so with every new intake of fuel the problem just starts again.  You could easily find yourself paying a fortune for biocides and additives that will never truly eliminate diesel bug.  Some biocides work and they do have a place in good fuel management.  In the good old days  sulphur levels were much higher and the sulphur itself acted as a natural biocide,  so its removal is the reason why filters are becoming increasingly blocked by diesel bug.  To be effective you would have to dose every time you filled up, which, as we have already eluded, to will be expensive.

Staying Diesel bug Free

Consider, however, an alternative approach – what if you simply removed the water from your tank and made sure it could never return?  If you can do this easily and cheaply and have full peace of mind that your filters were going to be sludge and slime-free and your engine safe then don’t you think it’s worth investigating?  

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Peter Weide is MD of MarShip UK, a UK based company specializing in optimising the efficiency of marine diesel engines. Advising on maintaining the cleanliness of Air, Fuel and Lubricating oil, we regularly recommend solutions to operators and appear regularly in industry press, with our full range of diesel additives DieselAid we can offer solutions for most operating conditions and wont advise them if you don’t need them.

Prolonging Efficiency in Your Diesel Engine