Simple Fuel System Checks to Keep Your Marine Diesel Healthy

by Ian Kuhl on April 16, 2016

in Diesel Engines Stories, Marine Safety, Workshops

Your Diesel Fuel is your Boat’s Blood
Good Fuel  = Healthy Engine 

Marine Fuel System Basics

  • Fuel tanks should be clean and full. Try not to run tanks too low, as this makes it easier to pick up water.
  • Use a quality fuel additive each time you fuel to prevent algal growthFuel Filters on Shy Alba
  • Tanks must be well secured in the boat.
  • Always have a combination primary fuel filter / water trap and an engine fuel filter.
  • Primary fuel filters should be changed regularly – the same time as an oil change – every 100 hours. Secondary filters may not require changing as regularly.
  • Some engine filters can be replaced with a standard fuel filter / water trap unit, e.g. CAV.
  • Keep spare fuel filters (plus two extras!) in a clean and dry place, in a plastic bag.
  • Use only high quality fuel lines. They must be clean, internally and externally, and easily removable with quality twin hose clamps.
  • Check your fuel tank breather line is not blocked or letting water in. Check deck fillers to see if the o-ring is sealing correctly.
  • Makes sure you know where the engine bleeding points and the fuel lift pump are and how to bleed the engine if it runs dry.
  • Don’t rely solely on your fuel gauge; use the logged fuel taken aboard and hours run to check. Sight Gauges and Dipsticks are great.

Would you like to learn even more about your Marine Diesel Engine?

Click here for our Marine Diesel Engines for Beginners course.

Tips to prevent ‘Diesel Bugs’Shy Alba Engine Room

  • Keep a constant eye on the condition and colour of your fuel. If it goes dark it could be getting the ‘bug’.
  • Always use a biocide fuel additive when refueling, this prevents ‘Diesel Bugs’. These is a specific algae that grow in fuel tanks and they can rapidly block fuel filters.
  • Ask around for the best fuel dock that sells fresh diesel with biocide added to their holding tanks.


How about you? Any more fuel system tips you’d like to share – or war stories you have learned from?

Please share them in the comments below or send us an email –

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