Operation Section
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HARD START
Checks Action
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 Make sure the vehicle’s operator is using the correct starting procedure.
Sensor Checks
• 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.
Fuel System
Checks
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.
Ignition System
Checks
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.
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