Engine Cranks But Does Not Run

Engine Cranks But Does Not Run

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The 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.

Diagnostic Aids

Inspect for any of the following conditions:

* Insufficient fuel can cause a no start condition. Thoroughly inspect the fuel delivery system for sufficient fuel volume to the fuel injectors. Inspect the fuel supply components for partial blockage or restrictions.

* Fuel injectors with partially blocked and restricted nozzles, or a malfunctioning solenoid, can cause a no start condition. Refer to Fuel Injector Diagnosis Fuel Injector Diagnosis.

* There may be fuel spray at the fuel injectors and the indicated fuel pressure may be correct, yet there may not be enough fuel to start the engine. If the fuel injectors and the injector circuit are OK, and fuel spray is detected, the fuel injector ON time may be inadequate. If the ECM receives incorrect inputs from the various information sensors, the fuel delivered by the fuel injectors may be inadequate to start the engine. Check all the engine data parameters with a scan tool and compare the values indicated with the expected values or the values from a known vehicle in good condition.

* Check the crankshaft position sensor engine reference signal with a scan tool. Observe the engine speed parameter while cranking the engine. The scan tool should indicate a steady 200-300 RPM while cranking. If erratic values, such as sudden spikes in the engine speed, are displayed, the engine reference signal is not stable enough for the engine to start and run properly.

* Inspect the engine for good secure electrical grounds.

* If the engine almost starts and then stalls, check for an open in the ground circuits of the crankshaft position sensor and the camshaft position sensor - Intake or camshaft position sensor - Exhaust.

* Water or foreign material in the fuel can cause a no start or engine will not stay running condition. During freezing weather water can freeze inside the fuel system. The engine may start after 30 min in a heated repair shop. The malfunction may not recur until parked overnight in freezing temperatures. Extreme weather conditions can cause contaminated fuel to prevent the vehicle from starting.

* A vehicle that starts and runs after being brought to the repair shop for a no start condition, may have an ignition system that is susceptible to moisture. Spray water on the ignition system components and the wiring in order to check for an engine starting or will not stay running concern.

Reference Information

Schematic Reference

Engine Controls Schematics [1][2]Electrical Diagrams

Connector End View Reference

Component Connector End Views Fuel Pump and Level Sensor Assembly

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Special Tools

* CH 48027 - Digital Pressure Gauge

* EN 36012-A - Ignition System Diagnostic Harness

* EL 26792 - HEI Spark Tester

* J 34730-2C - Injector Test Lamp

For equivalent regional tools, refer to Special Tools Tools and Equipment.

Circuit/System Testing

Note: This diagnostic assumes the following:

* The battery is completely charged.

* The engine cranking speed is acceptable.

* There is adequate fuel in the fuel tank.

1. Crank the engine for up to 15 s.

2. Verify that DTC P0117, P0118, P0122, P0123, P018C, P018D, P0222, P0223, P0231, P0232, P023F, P025A, P0335, P0336, P0513, P0562, P0563, P0601, P0602, P0603, P0604, P0606, P0628, P0629, P062F, P0633, P0685, P0689, P0690, P1516, P1631, P1682, P16F3, P2101, P2119, or P2610 are not set.

• If a DTC is set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.

• If a DTC is not set

3. Ignition ON

4. Verify the security indicator on the instrument cluster illuminates momentarily.

• If the security indicator stays ON or is flashing
Review the Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for Immobilizer system DTCs. For additional information, refer to Immobilizer Description and Operation Immobilizer.

• If the security indicator does not stay ON and is not flashing

5. Engine cranking, verify the scan tool Engine Speed parameter indicates an engine speed greater than 0 rpm.

• If the engine speed is not greater than 0 rpm.
Refer to DTC P0335 or P0336 P0335.

• If the engine speed is greater than 0 rpm.

Note: It may be necessary to secure the EN 36012-A to the spark plug boots with electrical tape.

6. Install the EN 36012-A Ignition System Diagnostic Harness to the spark plug boots.

7. Connect the EL 26792 Spark Tester between the boot of a spark plug wire and ground.

8. Connect the remaining wires to the appropriate cylinders.

Note: An erratic or weak spark is considered a no spark condition.

9. Engine cranking, verify the spark tester sparks.

• If the spark tester does not spark
Refer to Electronic Ignition System Diagnosis Electronic Ignition (EI) System Diagnosis for diagnosis of the ignition coil.

• If the spark tester does spark

10. Ignition OFF, all accessories OFF, install the CH 48027 Digital Pressure Gauge.

11. Ignition ON.

Note:

* The fuel pump may need to be commanded ON a few times, in order to obtain the highest possible fuel pressure.

* Do not start the engine for this test.

12. Verify that the fuel pump runs and that the fuel pressure is between 345-414 kPa (50-60 PSI) when commanding the Fuel Pump Enable ON with a scan tool.

• If the fuel pump does not run or if the fuel pressure is not within the specified range
Refer to Fuel System Diagnosis Fuel System Diagnosis.

• If the fuel pump runs and the fuel pressure is within the specified range

13. Ignition OFF, disconnect the harness connector at a Q17 Fuel Injector.

14. Connect the J 34730-2C - Injector Test Lamp between the control circuit and the ignition voltage circuit.

15. Verify the injector test lamp flashes while cranking the engine.

• If the injector test lamp does not flash
Refer to Fuel Injector Diagnosis Fuel Injector Diagnosis.

• If the injector test lamp does flash

16. Verify the following conditions do not exist:

* Air intake duct to the throttle body collapsed

* Air filter or air intake system restricted

* Gas or coolant fouled spark plugs. Refer to Spark Plug Inspection Testing and Inspection.

* A skewed manifold absolute pressure (MAP) sensor.

* A skewed engine coolant temperature (ECT) sensor.

* Exhaust system restricted. Refer to Restricted Exhaust Restricted Exhaust.

* Contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis Testing and Inspection.

* An engine mechanical condition, for example, worn timing belt or low compression. Refer to Symptoms - Engine Mechanical Symptoms - Engine Mechanical.

• If a condition exists
Repair as necessary.

• If a condition does not exist

17. All OK.

Repair Verification

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

Spark Plug Replacement Service and Repair