Mitsubishi S12U Operation & Maintenance Manual page 98

Chapter 9
TROUBLESHOOTING
Problem
(1) Improper fuel injection timing
a Malfunction of camshaft drive
b Deviation of fuel ignition timing due to
worn fuel injection pump tappet roller or
camshaft cam
(2) Poor spray condition of fuel injection nozzles
a Sticking of needle valve in fuel injection
nozzle, or improper valve seat sealing
b Fuel injection nozzle valve opening
pressure is low
c Damaged or broken nozzle spring
d Large amount of fuel leaks from nozzle
C
Engine emits
(3) Insufficient compression pressure (cylinder internal temperature does not reach igni-
large amount of
exhaust smoke.
(Check the
cause of igni-
tion failure a Inadequate rotation speed
despite suffi-
cient amount of
injected fuel.)
b Inlet/exhaust valve not contacting valve
seat properly
c Valve remaining open
d Leaking of compression pressure due to
worn cylinder liners or sticking of piston
rings
e Leaking of compression pressure from
cylinder cover
(4) Inappropriate fuel
a Inappropriate fuel or water in fuel
9-4
Table 9-2 Engine turns, but it does not start (2 / 2)
Cause
tion temperature)
Remedy
Inspect camshaft drive section, and adjust
fuel injection timing correctly.
Replace if worn.
Check with nozzle tester, and disassemble
and repair, or replace.
Using nozzle tester, adjust adjustment
screw so that fuel is injected at specified
valve opening pressure.
Replace if damaged.
Clean mounting surfaces of nozzle and
holder. Replace if necessary.
If starting air pressure is low, increase
pressure.
If engine oil viscosity is high, heat oil or
change oil to one with appropriate viscos-
ity.
Repair if there are other abnormalities.
Disassemble and repair by lapping valve
in valve seat, or replace if necessary.
Check for sticking of valve and valve
guide, incorrect tappet assembly, and
valve clearance, and correct abnormalities
if necessary.
Disassemble and repair, or replace if nec-
essary.
Check for gas leaks, and tighten cylinder
cover properly. Repair gas seal surface or
replace gas seal ring, if necessary.
Drain fuel and check. Change to higher-
quality fuel, if necessary.