P
roblems with the fuel supply are some of the
most common causes of breakdowns and poor
performance with marine diesel engines. This can
also lead to dirty or contaminated fuel plugging
filters, damage to the injection pump or injectors, or
accidently running out of fuel. However, ensuring a
reliable supply of clean diesel all the way from the deck
fill, through the tank to the engine’s injection pump is
not complicated. With minimal time and money, you
can ensure a reliable supply and prevent the expense
and dangers of a breakdown.
Clean fuel is essential for a diesel engine to perform
well and operate trouble free. Tolerances can be down
to less than two microns (2/1,000,000 of a metre),
allowing no space between working parts for particles
to pass without blocking the flow of fuel.THREE CAUSES OF CONTAMINATION
Water
Water in any form – vapour or droplets – is harmful
to a diesel engine. Even tiny amounts of water in
the injection pump or injectors can cause significant
damage.
Water can get into a fuel tank through several
sources: fuel from a filling station’s contaminated
tanks, a missing or damaged O-ring in the fuel deck
filler cap or failure to tighten, and poor fuelling
practices. For example, it’s important to avoid fuelling
in the rain or with spray. Condensation in the tank is
rarely a source of any significant water.
Water can cause damage in several ways. In some
cases it displaces diesel, exposing metal surfaces to
abrasion. It can also lead to etching – when combined
water and sulphur in the fuel produces acid which
‘eats’ into metal surfaces.Spalling is another common problem when water
forced into cracks causes microscopic flaking, while
the collapsing water vapour bubbles involved in
cavitation is often responsible for causing metal
fatigue and pitting.Above:Check the
O-ring each time
you open the fuel
filler cap. Missing,
damaged or badly-
seated O-rings are
a common cause of
water in a fuel tank.
Below:There are
four types of primary
fuel filters.bluewatermag.com.au 51A reliable diesel supply