S-7 Engine Runs Rough Or Is Unstable - Komatsu PC88MR-10 Shop Manual

40 Troubleshooting
Troubleshooting of engine (S-mode)

S-7 Engine runs rough or is unstable

Engine runs rough or is unstable.
Failure
Related
If any failure code is displayed, perform troubleshooting for that code first.
information
No. Cause
1 Insufficient fuel in tank
Clogged air breather hole in
2
fuel tank cap
Clogged fuel filter element
3
Foreign material in fuel
4
Air in fuel piping system
5
Leakage from fuel piping
6
system
Fuel leakage from boost
7
system
Defective mass air flow and
8
temperature sensor
40-524
(D37-A40-400-A-Z0-A)
Point to check, remarks
Fuel tank is empty.
Air breather hole in fuel tank cap is clogged.
Check used hours of fuel filter. If used
beyond specified hours, fuel filter element
may be clogged.
Rust and water are found in fuel drained
from fuel tank.
Air is bled during air bleeding of fuel system.
(Reference: See Testing and adjusting,
"Bleeding air from fuel system".)
Fuel leaks from fuel piping.
(Reference: See Testing and adjusting,
"Testing fuel circuit for leakage".)
Check boost system (between turbocharger
outlet and aftercooler, aftercooler and air
intake manifold) for fuel leakage.
Replace sensor and check whether
symptom disappears.
(Failure code may not be generated if
sensor is covered with dust.)
Remedy
Add fuel.
Flush air breather hole
in fuel tank cap and
clean surrounding
area.
Replace fuel filter
element.
Replace fuel.
Perform air bleeding.
Repair or replace fuel
piping.
Repair or replace fuel
piping related parts.
Repair or replace
boost piping related
parts.
Replace mass air flow
and temperature
sensor.
PC88MR-10