Komatsu 75001, Shop Manual

Page: 987 / 1293

SEN03850-00
40-600
6
WA250, 250PZ-6
600 Troubleshooting of engine (S-mode)
S-1 Starting performance is poor
S-1 Starting performance is poor
1
*1: Failure codes [CA559] and [CA2249] in the display of code
General causes why starting performance is poor
q
Defective electrical system
q
Insufficient supply of fuel
q
Insufficient intake of air
q
Improper selection of fuel
a The common rail fuel injection system (CRI) controls the
fuel injection timing electrically. Accordingly, even if the
starting operation is carried out, the engine may not start
until the crankshaft revolves 2 turns at maximum. This phe-
nomenon does not indicate a trouble, however.
Causes
C
log
ge
d
air
cl
ea
ne
r e
le
m
en
t
D
e
fe
ct
iv
e
c
o
nt
ac
t of
va
lv
e an
d
v
a
lv
e
s
e
at
W
o
rn
pi
st
on
r
ing
, c
y
lin
d
e
r
C
log
ge
d
air
br
e
at
he
r h
ol
e o
f f
ue
l t
a
nk
c
ap
Le
ak
in
g or
cl
og
ge
d f
ue
l p
ip
in
g,
en
tr
y
o
f
a
ir
C
log
ge
d f
ue
l f
ilt
er
,
e
le
m
e
nt
S
tuc
k,
sei
z
e
d
su
pp
ly
p
u
m
p
pl
un
ge
r
D
e
fe
ct
iv
e
in
je
c
tor
D
e
fe
ct
iv
e
in
ta
ke
ai
r he
at
er
sy
st
em
D
e
fe
ct
iv
e
al
te
rn
a
tor
(
re
g
u
lat
or
se
ct
io
n)
D
e
fe
ct
iv
e
al
te
rn
a
tor
(
g
e
ner
a
tor
se
ct
io
n)
D
ef
ec
ti
v
e
or
de
te
ri
o
rat
e
d ba
tt
e
ry
Q
u
es
ti
on
s
Confirm recent repair history
Degree of use of machine Operated for long period E E E
Starting performance
Became worse gradually
Q w w Q
Engine starts easily when warm w w
Non-specified fuel is being used Q Q Q
Replacement of filters has not been carried out according to Operation and
Maintenance Manual
w w Q Q
Oil must be added more frequently w
When engine is preheated or when temperature is low, preheating monitor does not
indicate normally
w
During operation, charge level monitor indicates abnormal charge w w
Dust indicator is red w
Air breather hole of fuel tank cap is clogged w
Fuel is leaking from fuel piping w Q
When priming pump is operated, it makes no reaction or it is heavy w Q
Starting motor cranks engine slowly w
Ch
e
c
k i
te
m
s
While engine is cranked
with starting motor,
If air bleeding plug of fuel filter is removed, fuel does not
flow out
w
Much fuel returns from the injector w
When exhaust manifold is touched immediately after starting engine, temperature of
some cylinders is low
w
Engine does not pick up smoothly and combustion is irregular
Q Q w
There is hunting from engine (rotation is irregular) Q w Q
Blow-by gas is excessive w
T
rou
bl
es
ho
ot
ing
Inspect air cleaner directly
q
When compression pressure is measured, it is found to be low q q
When air is bled from fuel system, air comes out q
Inspect fuel filter, strainer directly q
Carry out troubleshooting according to “No-pressure feed by supply pump (*1)” in display
of code
q
When a cylinder is cut out for reduced cylinder mode operation, engine speed does not
change
q
When starting switch is turned to HEAT, intake air heater mount does not become warm q
Is voltage 20 – 30 V between alternator terminal B and terminal E with
engine at low idle?
Yes q
No q
When specific gravity of electrolyte and voltage of battery are measured, they are low
q
Remedy
Cl
e
a
n
R
e
pl
ac
e
R
e
pl
ac
e
Cl
e
a
n
Co
rre
c
t
R
e
pl
ac
e
R
e
pl
ac
e
R
e
pl
ac
e
R
e
pl
ac
e
R
e
pl
ac
e
R
e
pl
ac
e
R
e
pl
ac
e