Mitsubishi S12U User Manual

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

Mitsubishi S12U Specifications

General

Brand	Mitsubishi
Model	S12U
Category	Engine
Language	English