regulations have led to engines with high-pressure
fuel systems. Th e internal components of modern
fuel injectors are oft en extremely small and very
susceptible to wear or sticking due to particles
and other kinds of contamination.
Unclean fuel can decrease the life of these
components and may even cause malfunctions
that could result in severe damage to other parts
of a vehicle’s fuel system and engine.
Th at’s why premium fuel fi ltration is a must.
When injectors are functioning at the optimum
level and delivering clean diesel fuel to the
engine, the result is peak performance in these
three areas:
Improved fuel economy – Clean fuel moves
smoothly through today’s high-pressure fuel injectors,
which translates to more miles per gallon.
Proper fuel system function – Eliminating even
the smallest particles, down to 1 to 3 microns,
can prevent signifi cant damage to fuel pumps
and injectors.
Reduced downtime – Fleets spend more time
on the road when fuel system components reach
or surpass their expected service intervals.
Fuel Filters
Fuel fi lters naturally build resistance to the fl ow
of fuel as they go about their job of removing
unwanted contaminants from the fuel system.
Fuel fi lters will become restricted or plugged
over the course of their lives. Th is is an expected
result.
Service personnel should conduct a thorough
investigation of the fi lter and the fuel source
anytime a fuel fi lter is suspected of delivering
less than its expected life.
However, in no case should a more “open” fi lter
be substituted to fi x a perceived problem with
premature plugging. Substitution of a more “open”
fi lter may prolong a fi lter’s life before plugging
occurs, but it will also allow unwanted contaminants
to pass downstream. Th at will eventually
impact the life of other, more expensive fuel
system components.
Common Fuel Contaminants
Th e most common fuel contaminants are:
1.Water. Water is the greatest concern to fl eets
and service personnel because it is the most
common form of contaminant. Water may be
introduced into the fuel supply during fueling
22 Fleet Maintenance | AUGUST 2017
when warm, moisture-laden air condenses on the
cold metal walls of fuel storage tanks, or from poor
housekeeping practices.
Water can introduce rust into the fuel system,
damage fuel injectors or reduce the lubricity of the
fuel, which can cause seizure of close-tolerance
assemblies such as plungers.
2. Fungus and bacteria. Th ese organisms
live in water and feed on the hydrocarbons
found in fuel. Called “humbugs” for short,
the active and multiplying colonies will spread
throughout a fuel system and quickly plug a fuel
fi lter. Th e result will be a slime coating over the
surface of the fuel fi lter’s media, dramatically
reducing the service life of the fi lter.
3. Wax. Wax is desirable as a source of energy
in diesel fuel, but it can cause problems
in cold weather conditions. Wax crystals form
as a result of cold temperature precipitation
of paraffi n.
» Service personnel should conduct a thorough
investigation of the fuel filter and the fuel
source anytime a fuel filter is suspected of
delivering less than its expected life.
Photo courtesy of Luber-finer
Never substitute a
more “open” filter.