Repair Section
2
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92
(2) White Smoke
White smoke: Uncombusted fuel that has been vaporized and then discharged.
• White smoke is generated when combustion occurs at a relatively low temperature, resulting in the exhaust of un-
combusted fuel and oil particles. White smoke is most likely to be generated when combustion chamber temperature
is low.
Source of White Smoke
(3) Black Smoke
Black smoke: Fuel that has been baked into soot and discharged.
• Black smoke is often referred to as just "smoke". Black smoke is generated when the injected fuel is poor in oxygen.
As the fuel is exposed to high temperatures, thermal breakdown occurs, leaving carbon behind. Black smoke occurs
when the injected fuel quantity is too large, or when the air-fuel mixture is rich due to an insufficient quantity of air.
Source of Black Smoke
1.2 Troubleshooting
Troubleshooting cautions
z Observe the following cautions to avoid decreased engine performance and fuel injector malfunctions.
• Use the designated fuel.
• Avoid water and foreign material intrusion into the fuel tank.
• Periodically check and clean the filter.
• Do not unnecessarily disassemble sealed components.
Troubleshooting notes
z The cause of malfunctions is not necessarily limited to the pump itself, but may also be related to the engine and/or fuel
systems. Further, the majority of malfunctions are the result of user error, and often can often be resolved through simple
checks and maintenance. Avoid any hasty removal of system components.
Basic Check Items
1 Late Injection Timing Fuel is injected when the piston is in the down stroke.
2 Cold Engine
Ignition occurs late and combustion is prolonged.
3 Poor Fuel Combustibility
4 Rise and Fall of Oil Pressure Oil undergoes partial thermal breakdown.
1 Large Fuel Injection Quantity Air-fuel mixture becomes rich.
2 Low Intake Air Quantity Air quantity is insufficient due to air filter clogging.
3 Poor Fuel Atomization The ratio of fuel to air worsens.
4 Retarded Fuel Injection Timing Air-fuel mixing time is insufficient.
1 Engine Oil 7 Fuel Supply to the Pump
2 Coolant 8 Injector Injection Status
3 Fan Belt 9 Supply Pump Timing Mark
4 Air Cleaner 10
Check for Loose or Disconnected Connectors, and
Modifications
5 Battery and Terminals 11 Idle Speed Status
6 Fuel System Leaks
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