Spectrum 3.0L GM, Parts & Service Manual

Page: 40 / 327

40
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 engine’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/crank
sensors.

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 a no start
condition.

Check Venturi assembly for proper installation and leakage.

Verify proper operation of the Shut-off solenoid Valves.

Verify proper operation of the system low pressure Regulator.

Check for air intake system leakage between the Throttle Body and Air
Filter Assembly. Check the fuel system pressures. Refer to the
Fuel
System Diagnosis
.
Ignition System Checks
NOTE: LPG requires higher secondary ignition system voltages for the
equivalent gasoline operating conditions.

Check for the proper ignition voltage output with
J 26792
tool 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 (oil fouling).

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/crank sen-
sor.
2. Check for improper gap, debris or faulty connections.