Fuel System - Doosan DX140R Shop Manual

Fuel System

When servicing any fuel system components, which can be
exposed to potential contaminants, prior to disassembly, clean
the fittings, mounting hardware, and the area around the
component to be removed. If the surrounding areas are not
cleaned, dirt or contaminants can be introduced into the fuel
system.
The internal drillings of some injectors are extremely small and
susceptible to plugging from contamination. Some fuel injection
systems can operate at very high pressures. High pressure fuel
can convert simple particles of dirt and rust into a highly
abrasive contaminant that can damage the high pressure
pumping components and fuel injectors.
Electrical contact cleaner can be used if steam cleaning tools
are not available. Use electrical contact cleaner rather than
compressed air, to wash dirt and debris away from fuel system
fittings. Diesel fuel on exposed fuel system parts attracts
airborne contaminants.
Choose lint free towels for fuel system work.
Cap and plug fuel lines, fittings, and ports whenever the fuel
system is opened. Rust, dirt, and paint can enter the fuel system
whenever a fuel line or other component is loosened or removed
from the engine. In many instances, a good practice is to loosen
a line or fitting to break the rust and paint loose, and then clean
off the loosened material.
When removing fuel lines or fittings from a new or newly-painted
engine, make sure to remove loose paint flakes/chips that can
be created when a wrench contacts painted line nuts or fittings,
or when quick disconnect fittings are removed.
Fuel filters are rated in microns. The word micron is the
abbreviation for a micrometer, or one millionth of a meter. The
micron rating is the size of the smallest particles that will be
captured by the filter media. As a reference, a human hair is
0.003 mm (3/1000 in) in diameter. One micron measures
0.00004 mm (4/100,000 in). The contaminants being filtered out
are smaller than can be seen with the human eye, a magnifying
glass, or a low powered microscope.
The tools used for fuel system troubleshooting and repair are to
be cleaned regularly to avoid contamination. Like fuel system
parts, tools that are coated with oil or fuel attract airborne
contaminants. Remember the following points regarding your
fuel system tools:
• Fuel system tools are to be kept as clean as possible.
• Clean and dry the tools before returning them to the
tool box.
• If possible, store fuel system tools in sealed
containers.
• Make sure fuel system tools are clean before use.
QSB4.5 Engine
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