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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 Instructionsprovides an overview of each diagnostic category.

Circuit/System Description

This Engine Cranks but Does Not Run diagnostic 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.

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 (With J39021 or With Tech 2) Fuel Injector Diagnosis (With J39021 or With Tech 2)Fuel Injector Diagnosis (With CH47976) Fuel Injector Diagnosis (With CH 47976).
* 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 engine control module (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 good vehicle.
* Check the crankshaft position (CKP) 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 CKP sensor and the camshaft position (CMP) sensor.
* 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 minutes 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 Connector End Views By Name
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

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 Relearningfor scan tool information
Special Tools

* CH 48027 - Digital Pressure Gauge
* CH 48027-100 - Digital Pressure Gauge
* J 26792 (SA91992) - Spark Tester
* J 43244 - Relay Puller Pliers

Circuit/System Verification

Note: This diagnostic assumes the following:

* The battery is completely charged. Refer to Battery Inspection/Test Battery Inspection/Test.
* The engine cranking speed is acceptable. Refer to Engine Cranks Slowly Engine Cranks Slowly.
* There is adequate fuel in the fuel tank.

1. Crank the engine for 15 seconds. Observe the DTC information with a scan tool. The following DTCs should not be set:
DTC P0016, P0017, P0201-P0204, P0230, P0335, P0336, P0351-P0354, P0601, P0602, P0603, P0604, P0606, P0607, P060D, P062F, P0685, P0689, P0690, P1516, P1682, P2610.

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

2. Ignition ON, observe the VTD Fuel Disable parameter with a scan tool. The parameter should display Inactive.

• If Active is displayed, refer to Symptoms - Engine Controls Symptoms - Engine Controls.

3. Ignition OFF, disconnect the fuel pump relay using the J 43244 - Pliers.
4. Connect a J 26792 (SA91992) - Tester to the boot of an ignition coil of a cylinder and ground.

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

5. While cranking the engine, verify that the spark tester sparks.

• If there is no spark, refer to Electronic Ignition System Diagnosis Electronic Ignition System Diagnosis.

6. Ignition OFF, install the fuel pump relay.
7. Ignition ON, command the fuel pump ON with a scan tool. You should hear the fuel pump turn ON.

• If the fuel pump does not turn ON, refer to Fuel Pump Electrical Circuit Diagnosis Fuel Pump Electrical Circuit Diagnosis.

8. Ignition OFF, install the CH 48027 - Gauge or CH 48027-100 - Gauge. Refer to Fuel Pressure Gauge Installation and Removal Fuel Pressure Gauge Installation and Removal.

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.

9. Ignition ON, command the fuel pump ON with a scan tool. The fuel pressure should be between 345-414 kPa (50-60 psi).

• If the fuel pressure is not within the specified range, refer to Fuel System Diagnosis Fuel System Diagnosis.

10. Verify that the following conditions do not exist:

* Collapsed air intake duct to the throttle body
* Restricted air filter element
* Spark plugs for being gas or coolant fouled
* A skewed manifold absolute pressure (MAP) sensor-Refer to DTC P0106 P0106.
* A skewed engine coolant temperature (ECT) sensor-Refer to Temperature Versus Resistance Temperature Versus Resistance.
* Exhaust system restricted-Refer to Restricted Exhaust Restricted Exhaust.
* Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis Alcohol/Contaminants-in-Fuel Diagnosis.
* Engine mechanical condition, for example, worn timing belt or low compression-Refer to Symptoms - Engine Mechanical Symptoms - Engine Mechanical or Engine Compression Test Testing and Inspection.

• If you find any of the above conditions, repair as necessary.

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