Handling Fuel System Parts; Releasing Residual Pressure In Fuel System - Komatsu 114E-3 Series Shop Manual

SEN00455-01

Handling fuel system parts

a Precautions for testing and maintaining fuel
system
The common rail fuel injection system (CRI)
consists of more precise parts than the con-
ventional fuel injection pump and nozzle. If for-
eign matter enters this system, it can cause a
trouble.
When testing and maintaining the fuel system,
take care more than the past. If dust, etc. sticks
to any part, wash that part thoroughly with
clean fuel.
a Precautions for replacing fuel filter cartridge
Be sure to use the Komatsu genuine fuel filter
cartridge.
Since the common rail fuel injection system
(CRI) consists of more precise parts than the
conventional fuel injection pump and nozzle, it
employs a high-efficiency special filter to pre-
vent foreign matter from entering it. If a filter
other than the genuine one is used, the fuel
system may have a trouble. Accordingly, never
use such a filter.
12
1 Releasing residual pressure in
fuel system
a Pressure is generated in the low-pressure cir-
cuit and high-pressure circuit of the fuel sys-
tem while the engine is running.
Low-pressure circuit:
Feed pump – Fuel filter – Fuel supply
pump
High-pressure circuit:
Fuel supply pump – Common rail –
Fuel injector
a The pressure in both low-pressure circuit and
high-pressure circuit lowers to a safety level
automatically 30 seconds after the engine is
stopped.
a Before the fuel circuit is tested and its parts are
removed, the residual pressure in the fuel cir-
cuit must be released completely. Accordingly,
observe the following.
k
Before testing the fuel system or removing
its parts, wait at least 30 seconds after stop-
ping the engine until the residual pressure
in the fuel circuit is released. (Do not start
the work just after stopping the engine
since there is residual pressure.)
30 Testing and adjusting
114E-3 Series
1