Doosan D439E - Page 158

D439E Service Manual 4. Fuel system
156
Unstable idle or engine stall.
Check fuel system
NG
Check injection timin
g
• Supply pump
• Fuel filter
• Fuel pressure regulator NG
Check fuel pressure
OK
Injection state
NG
Check injector
OK
• Wiring connection
• Power to ECU
1. Fusible link
2. Fuse
3. Control relay
• Engine coolant temperature
sensor
• Injection signal circuit
1. Injector wiring
2. ECU
NG
Check engine control system
OK
OK
Self dia
g
nosis
Trouble code
• Use Hi-scan
Check fuel supply to injector
• Fuel in the tank
• Fuel pressure
• Fuel line (Leakage, deformation)
• Fuse
• Supply pump
• Fuel filter
• Fuel pressure
OK
NG
NG
Check air cleaner element Clean or replace element
Check idle speed
Standard : 750rpm (A/C OFF)
850rpm (A/C ON)
Check ECU
OK
OK
NG
NG