Checks
| Action
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DEFINITION: The engine cranks OK but does not start for a long time.
The engine does eventually run, or may start but immediately dies.
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Preliminary
Checks
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| • | Ensure that the vehicle's operator is using the correct starting
procedure. |
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Sensor Checks
|
| • | Inspect the Engine Coolant Temperature (ECT) sensor with the scan
tool. Compare the engine coolant temperature with the ambient air temperature
on a cold engine. Inspect for high resistance in the coolant sensor circuit
if the coolant temperature reading is more than 5 degrees greater
or less than the ambient air temperature on a cold engine. Refer to DTC P0118
ECT Sensor Circuit High Voltage or DTC P1115 ECT Sensor CKT Intermittent
High Voltage in Engine Controls - 5.0, 5.7L in the C/K Truck Service
Manual. |
| • | Inspect the Throttle Position (TP) sensor. The control module
will not control the idle if a sticking throttle shaft or binding linkage
causes a high TP sensor voltage (open throttle indication). The scan
tool should display less than 0.85 volt with the throttle closed
while monitoring the TP sensor voltage. |
| • | Inspect the Crankshaft Position Sensor (CKP). |
| • | Inspect the Mass Air Flow (MAF) sensor. |
|
Fuel System Checks
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Important:: A closed CNG manual fuel shut-off valve will create an extended crank
condition.
| • | Verify proper operation in the fuel pump relay. (The fuel pump
relay circuit supplies a voltage signal to the AF system ECU and lock-off
relay.) Refer to Fuel Pump Circuit Diagnosis in Engine Controls -
5.0, 5.7L in the C/K Truck Service Manual. |
| • | Inspect the Gas Distribution Adapter (GDA) for proper installation
and leakage. |
| • | Inspect for an open NGO enable circuit. |
| • | Inspect for a skewed or disconnected Fuel Sending Unit (FSU). |
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