Doosan D20S-5 Operation & Maintenance Manual page 133

HARD START
Checks
DEFINITION: The engine cranks OK, but does not start for a long time. The engine does eventually run, or
may start but immediately dies.
Preliminary Checks
Sensor Checks
Fuel System
Checks
Ignition System
Checks
Make sure the vehicle's operator is using the correct starting procedure.
• Check the Engine Coolant Temperature sensor with the DST. Compare the
engine coolant temperature with the ambient air temperature on a cold engine. If
the coolant temperature reading is more than 10 degrees greater or less than the
ambient air temperature on a cold engine, check for high resistance in the
coolant sensor circuit. Check the cam angle sensor.
• Check the Throttle Position (TPS) and Foot Pedal Position (FPP) sensor
connections.
Important: A closed LPG manual fuel shut off valve will create an extended crank
OR no start condition.
• Verify the excess flow valve is not tripped or that the manual shut-off valve is not
closed.
Check mixer assembly for proper installation and leakage.
• Verify proper operation of the low pressure lock-off solenoid.
• Verify proper operation of the EPR.
• Check for air intake system leakage between the mixer and the throttle body.
Check the fuel system pressures. Refer to the Fuel System Diagnosis.
Note: LPG being a gaseous fuel requires higher secondary ignition system voltages
for the equivalent gasoline operating conditions.
• Check for the proper ignition voltage output with J 26792 or the equivalent.
• Verify that the spark plugs are the correct type and properly gapped.
Check the spark plugs for the following conditions:
• Wet plugs.
• Cracks.
• Wear.
• Burned electrodes.
• Heavy deposits
• Check for bare or shorted ignition wires.
• Check for moisture in the distributor cap.
• Check for loose ignition coil connections.
Important:
1. If the engine starts but then immediately stalls, check the cam angle sensor.
2. Check for improper gap, debris or faulty connections.
Action
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Operation Section