This Engine Cranks but Does Not Run is an organized approach to identify a condition which causes the engine to crank but not start. This diagnostic directs the technician to the appropriate system diagnosis.

This diagnostic assumes the system voltage levels are adequate for starter motor operation. Refer to Battery Inspection/Test , and Engine Cranks Slowly . Fuel level and fuel quality should be determined for correct diagnosis.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Special Tools

Attempt to start the engine. The engine should start and run.

1. Crank the engine for up to 30 seconds.
2. Observe the vehicle DTC information with a scan tool.

⇒	If any of the following DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to diagnose those DTCs: P0016, P0201-P0206, P0335, P0336, P0351-P0353, P0601, P0602, P0604, P0606, P0685, P1516, P2610

3. Ignition OFF for 90 seconds, determine the current vehicle testing altitude. Ignition ON, observe the scan tool MAP Sensor parameter. Compare the parameter to the Altitude Versus Barometric Pressure table. The MAP Sensor Pressure parameter should be within the specified range indicated in the table.

⇒	If the reading is not correct for your altitude, diagnose the MAP sensor. Refer to DTC P0106 .

4. Ignition ON, verify the scan tool injector circuit status parameters indicate Incomplete.

⇒	If the parameters do not indicate Incomplete, refer to DTC P0201, P0202, P0203, P0204, P0205, or P0206 .

5. Observe the engine speed parameter while cranking the engine.

⇒	If engine RPM is not indicated, refer to DTC P0335 or P0336 .

6. Install a J 26792 .
7. Crank the engine for 15 seconds. Spark should be observed from the J 26792 .

⇒	If spark is not observed refer to Electronic Ignition (EI) System Diagnosis .

8. With the ignition ON and the engine OFF, test the fuses that are supplied by the powertrain relay for voltage. The test lamp should illuminate at each test point for the following fuses:

•	Emission Fuse

•	Ignition 1 Fuse

⇒	If the test lamp does not illuminate on at least one side of each fuse, refer to DTC P0685, P0689, or P0690 .

Important: Additional DTCs may set when using the fuel pump output control.

9. Command the fuel pump ON and OFF. Fuel pump should energize when commanded ON and De-energize when commanded OFF.

⇒	If the fuel pump does not respond refer to Fuel Pump Electrical Circuit Diagnosis .

10. Turn OFF the ignition.
11. Install the CH-48027 Digital Pressure Gage. Turn ON the ignition and command the fuel pump ON while observing the CH-48027 . The fuel pressure should be between 384-425 kPa (56-62 psi).

⇒	If the fuel pressure is not within 384-425 kPa (56-62 psi) refer to Fuel System Diagnosis .

12. Inspect for the following conditions:

•	Compare the actual engine coolant temperature to the ECT parameter.

•	Air filter and air intake system for restrictions and obstructions

•	Test the fuel for ethanol content. Refer to Fuel Composition Diagnosis for 3.5L (RPO LZE), VIN Code K, E85 compatible engines only.

•	Test the fuel for contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis for non-E85 vehicles.

•	Inspect the spark plug and spark plug wires. Refer to Spark Plug Inspection and Spark Plug Wire Inspection .

•	Test the exhaust system for restrictions. Refer to Restricted Exhaust .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.