Handling Fuel System Equipment; Releasing Residual Pressure In Fuel System - Komatsu WA250-6 Shop Manual

110 Testing and adjusting, Part 1

Handling fuel system equipment

Handling fuel system equipment

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 replacement of fuel filter car-
tridge
The fuel filter cartridge used must be a genuine
Komatsu part.
The fuel injection pump and nozzle of the com-
mon rail type fuel injection system (CRI) are
consisted of more precision parts than those
used for the current pumps and nozzles. This
system, therefore, employs a special filter with
highly efficient filtering performance to prevent
mixing of foreign substances. Thus, substitut-
ing it with a non-genuine filter could cause
troubles in the fuel system. It is strictly prohib-
ited to use such part.
WA250, 250PZ-6
Releasing residual pressure in
1
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 – Supply pump
High-pressure circuit:
Supply pump – Common rail – 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.)
SEN03836-01
1
23
30-110