Engine Cranks But Does Not Run
Engine Cranks But Does Not Run
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Initial Inspection and Diagnostic Overview prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Initial Inspection and Diagnostic Overview for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Initial Inspection and Diagnostic Overview provides an overview of each diagnostic category.
Circuit/System Description
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. Fuel level and fuel quality must be determined for correct diagnosis.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Connector Views
Description and Operation
Starting System Description and Operation Description and Operation
Electrical Information Reference
* Circuit Testing Component Tests and General Diagnostics
* Connector Repairs Component Tests and General Diagnostics
* Testing for Intermittent Conditions and Poor Connections Component Tests and General Diagnostics
* Wiring Repairs Component Tests and General Diagnostics
* Battery Inspection/Test Battery Inspection/Test
* Engine Cranks Slowly Engine Cranks Slowly
* Electrical Center Identification Views Application and ID
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Programming and Relearning for scan tool information
Special Tools
* CH-48027 - Digital Pressure Gauge
* CH-48027-100 - Digital Pressure Gauge
* J 26792 (SA91992) - HEI Spark Tester
Circuit/System Verification
Attempt to start the engine. The engine should start and run.
Circuit/System Testing
1. Crank the engine while observing the scan tool vehicle DTC information.
• If any of the following DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle to diagnose those DTCs: P0016, P0201-P0206, P0230, P0335, P0336, P0351-P0353, P0449, P0601, P0602, P0603, P0604, P0606, P0607, P060D, P062F, P0685, P0689, P0690, P1516, P1682, P2610
2. 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 DTC P0106 P0106 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 Altitude Versus Barometric Pressure Altitude Versus Barometric Pressure.
3. Verify the following scan tool parameters indicate OK when the engine is cranked:
* Cylinder 1-6 Injector Circuit Short to Ground Test Status
* Cylinder 1-6 Injector Circuit Open Test Status
• If the parameters do not indicate the specified values, refer to DTC P0201, P0202, P0203, P0204, P0205, or P0206 P0201.
4. Verify the scan tool parameter Cylinder 1-6 Injector Circuit Short To Volts Test Status changes from Not Run to OK when the engine is cranked.
• If the parameters do not indicate the specified values, refer to DTC P0201, P0202, P0203, P0204, P0205, or P0206 P0201.
5. Crank the engine while observing the scan tool engine speed parameter.
• If engine RPM is not indicated, refer to DTC P0335 P0335.
6. Install a J 26792 (SA91992) - Spark Tester.
7. Crank the engine while observing the spark tester. The spark tester should spark.
• If spark is not observed, refer to Electronic Ignition System Diagnosis Electronic Ignition System Diagnosis.
8. With the ignition ON and the engine OFF, test the fuses that are supplied by the powertrain relay for voltage.
• If the test lamp does not illuminate on at least one side of each fuse, refer to DTC P0685, P0689, or P0690 P0685.
Note: Additional DTCs may set when using the fuel pump output control.
9. Command the fuel pump ON and OFF. The 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 Fuel Pump Electrical Circuit Diagnosis.
10. Turn OFF the ignition.
11. Install the CH-48027 - Gauge or the CH-48027-100 - Gauge. Turn ON the ignition and command the fuel pump ON while observing the CH-48027 - Gauge or the CH-48027-100 - Gauge. 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 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 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 Alcohol/Contaminants-in-Fuel Diagnosis for non-E85 vehicles.
* Inspect the spark plug and spark plug wires. Refer to Spark Plug Inspection Testing and Inspection and Spark Plug Wire Inspection Testing and Inspection.
* Test the exhaust system for restrictions. Refer to Restricted Exhaust Restricted Exhaust.
Repair Verification
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Spark Plug Wire Replacement Service and Repair
* Spark Plug Replacement Service and Repair