Failure Diagnosis - Doosan DP158L Series Operation & Maintenance Manual

8. Fuel system

Failure Diagnosis

Symptom
1. Engine does not start
A. Fuel is not supplied from the
fuel delivery pump
B. Fuel is not injected from the
fuel injection pump
C. Improper fuel injection timing
D. Fuel injection nozzle not
working
2. Engine starts but stops imme-
diately
3. Insufficient engine power
4. Engine knocking occurs
5. Excessive engine smoke and
knocking
6. Unstable engine power
7. Engine cannot reach the max.
speed
8. Unstable engine idling
Causes
• Clogged fuel pipe, or air entered the fuel pipe line
• Defective delivery pump valve
• Seized delivery pump piston or push rod
• Clogged fuel filter cartridge
• Air entered to the fuel filter or injection pump
• Seizure or defect in the plunger or delivery valve
• Defective installation of fuel injection pump bracket
• Defective adjustment of the fuel injection pump tappet
• Excessively worn cam of camshaft
• Seizure of needle valve of nozzle
• Fuel leakage between nozzle and needle valve
• Improper fuel injection pressure
• Clogged fuel filter or clogged pipe between fuel
delivery pump and injection pump
• Air entered into fuel
• Insufficient supply of oil by fuel delivery pump
• Clogged air breather in fuel tank, causing insufficient
fuel supply.
• Excessively work plunger
• Improper injection timing
• Defective delivery valve
• Excessive fuel leakage in injection nozzle
• Nozzle not working properly
• Early injection timing
• High nozzle injection pressure
• Nozzle not working properly
• Defective injection timing
• Too low nozzle injection pressure
• Broken nozzle spring
• Nozzle not working properly
• Excessively work plunger
• Defective delivery valve seat
• Excessive fuel supply
• Insufficient fuel supply
• Air entered into fuel
• Water entered into fuel
• Defective plunger operation
• Defective actuator operation
• Defective nozzle
• Injection start pressure different between cylinders
• Defective controller
• Nozzle not working properly
• Defective operation of actuator or controller
• Defective controller operation
• Defective plunger operation
• Defective magnetic pickup sensor
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Troubleshooting
• Correct
• Replace
• Disassemble / correct
• Clean / replace
• Bleed
• Disassemble / correct
• Inspect / correct
• Inspect / correct
• Replace
• Service or replace
• Service or replace
• Adjust
• Clean or replace
• Air bleeding
• Disassemble / correct
• Replace breather
• Replace
• Adjust
• Replace
• Service or replace
• Disassemble / correct
• Adjust
• Adjust
• Disassemble / correct
• Adjust
• Adjust
• Replace it
• Replace it
• Adjust
• Replace it
• Check feed pump
• Check feed pump
• Air bleeding
• Replace fuel
• Disassemble / correct
• Disassemble / correct
• Disassemble / correct
• Adjust
• Adjust
• Disassemble / correct
• Adjust
• Adjust
• Disassemble / correct
• Inspect or replace