Modern common rail diesel engines such as the Yanmar 40hp & 57hp have a far more sophiticated fuel system than the older, more traditional diesel engines. As a result, they have a lower tolerance for dirty fuel however precautions can be made to counter this concern.
Traditional diesel engines rely on the fuel pressure from the fuel pump to dictate the timing and quantity of fuel which is delivered to a pre-combustion chamber. With a common rail engine, the fuel is delivered through a high pressure rail, with solenoid valves controlling the timing and amount of fuel injected. This high pressure delivery gives a much larger number of smaller droplets of fuel, increasing the surface area to volume ratio and increasing performance. It brings advantages in increased fuel efficiency power whilst reducing noise and emmissions. This line or "rail" of pressurised fuel is where the "common rail" engine gets its name, and can be seen the the below Yanmar engine diagram.
Using the digitally controlled fuel injectors and a higher pressure fuel line, clean fuel is more ciritcal on a common rail diesel engine. Contaminents or miro-organisms (bacterial/yeast/mould) can serious damage or clog the injectors that run with far finer tolerances due to their high pressure requirement.
So how much of an issue it this? Ultimately fuel in many developed countries such as Australia, US and many European countries are consistantly high quality and therefore not of great concern. However, if cruising in countries where the quality of the fuel is unknown or known to be of low quality, then there are two recommendations to help this issue:
1) Fuel Additives:
There are many fuel additive products available in most chandleries. Additives are often useful for both lubrication and anti corrosion however in a marine environment, the critical aspect needed is to stop any biological growth in the fuel tank, fuel lines and injectors.
2) A Fuel polishing system:
This is an optional extra that can be fitted at the factory and works through a system of additional high pressure filters, circulating the fuel from the fuel source (the tank). This is opposed to filtering at the end of the fuel system in the engine room where the standard boat fuel filters are located.
The system offers a programmable fuel pump to schedule routine fuel cycles, circulating fuel in both the port and starboard tanks through an independent set of dual Racor filters. This process removes particles from the fuel before they enter the engine fuel line thus protecting both the engine and extending the life of the dedicated engine fuel filters.
For the Seawind 1370, the fuel polishing system can be found on the options page by searching options More informaiton can be found in the 1370 options page by searching "Fuel Polishing" in the options search to find Part number: 1370-15-07
https://www.seawindcats.com/options/seawind-1370/
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