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Yanmar Pleasure Boat Marine Engine Help

Water in the Fuel

Why does water in the fuel give us problems

Firstly, if there is too much it will not burn in the combustion chamber and your engine will not run.
Secondly, it supports rust / corrosion of the internal parts of the fuel system.
Thirdly, if there is but a drop or two it can burn with the diesel as hydrogen and oxygen, a very powerful combination, and blow a hole in the top of the piston, blow the tips off injectors, etc., all very depressing and expensive.
Fourthly, a microbiological organism, commonly called 'DIESEL BUG', can grow at the interface between the water and the fuel. This organism can block fuel filters and bring you to a stop anywhere. It is most common in warm, humid climates. This organism also generates acids. These acids attack highly polished metal surfaces like the inside of fuel injection pumps and injectors and can cause high fuel leakages past the plungers into the oil system. The oil system on the engine becomes seriously diluted with diesel, which may show up as a crankshaft or main bearing failure amongst other things. This nasty little bug has been know to totally destroy large engines!

How does water get in there?

...Every air space contains water vapour to one degree or other. In a metal tank the water vapour laden air touches the exposed inside area, and as the metal is cooler, condenses the moisture from the air. The water then runs down the sides to the bottom of the tank. Presto! This happens in every fuel storage tank from the refinery to, and including, your boat. The less fuel you keep in the tank, especially during high humidity months, the more water will accumulate.
Dont always run on EMPTY. If you're a racing fanatic, install a small tank and re-install the bigger one when you want to go cruising. If you're too poor to buy fuel you're too poor to own the boat, stuff happens!
...Rain gets into the filler while you're refuelling, keep it covered.
...You have two filler points on the deck, both look very sexy and exactly the same, except for the writing. I will bet money that one day 'someone' will put the wrong product in the wrong hole. This will ruin more than your weekend, whichever way it happens !
Install totally different looking fillers for water and fuel, preferably at different levels.

Once water is in there, how do I get rid of it?

Operate the water drains on the tank and the fuel filter / water separator regularly. If you are a commercial operator you should do it before the first start every day.
For accidental intakes, WAIT (24hrs) for the fuel and water to separate and drain the water from the tank and fuel filter drains.
If you need to clean out the tank or lines with something use methyl alchohol ( methylated spirits ) as it absorbs water. Dont run it through the engine though, it doesnt like it !

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