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
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:
* When attempting to start the engine, the mechanical portion of the vehicle key must be locked in the fully extended position with the fob parallel to the key. Leaving the key partially retracted or folded over when starting may interrupt transponder authentication and result in an intermittent no-start condition. In such instances, DTC B3055 may also be set. If an intermittent no-start complaint is received, it may be necessary to discuss with the customer their starting habits and verify they are locking the key in the fully extended position, fob parallel to the key, before starting.
* 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.
* The fuel injectors are calibrated to begin operating when fuel pressure reaches 0.7 MPa (101.5 psi) at 20-32°C (68-90°F). This specification will vary when the temperature is outside of this range.
* Fuel injectors with partially blocked and restricted nozzles, or a malfunctioning solenoid, can cause a no start condition. Refer to Fuel Injector Solenoid Coil Test Fuel Injector Solenoid Coil Test.
* 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 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.
* 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 Sunshade - Left
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 Control Module References for scan tool information
Special Tools
* CH-48027 - Digital Pressure Gauge
* J 26792 - HEI Spark Tester
For equivalent regional tools, refer to Special Tools Tools and Equipment.
Circuit/System Verification
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. Engine cranking, observe the DTC information with a scan tool. Verify the following DTCs are not 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, engine OFF, observe the Theft Deterrent LED located on the instrument panel cluster. The LED should illuminate momentarily and then go out.
• If the LED stays ON or is flashing, review the scan tool DTC information for Immobilizer system DTCs-Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle. For more information, refer to Immobilizer Description and Operation Immobilizer.
3. Engine cranking, observe the scan tool Engine Speed parameter. The scan tool should indicate an engine speed greater than 0 RPM.
• If the engine speed is 0 RPM refer to DTC P0335 or P0336 P0335 for further diagnosis.
Note: Use the J 26792 - HEI spark tester to verify the output of each T8 ignition coil.
4. Ignition OFF, disconnect the T8 ignition coil from the cylinder and spark plug.
5. Connect the J 26792 - HEI spark tester to the boot of the T8 ignition coil and ground.
Note: An erratic or weak spark is considered a no spark condition.
6. Engine cranking, verify that the spark tester sparks.
• If there is no spark on any cylinder tested, refer to Electronic Ignition System Diagnosis Electronic Ignition (EI) System Diagnosis.
7. Ignition OFF, install the CH-48027 - digital pressure 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.
8. Ignition ON, engine OFF, command the Fuel Pump Enable ON with a scan tool. Verify the fuel pressure is between 345-690 kPa (50-100 psi) with the fuel pump running.
• If the fuel pump does not run, or if the fuel pump runs but the fuel pressure is not within the specified range, refer to Fuel System Diagnosis Fuel System Diagnosis.
9. Verify that the fuel pressure, after the fuel pump has turned off, decreases to 500-599 kPa (72-87 psi), and does not decrease more than 34 kPa (5 psi) in 1 minute from that point.
• 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 gas or coolant fouled
* A skewed B74 manifold absolute pressure (MAP) sensor-Refer to DTC P0106 P0106.
* A skewed B74 engine coolant temperature (ECT) sensor-Refer to Temperature Versus Resistance Electrical Specifications.
* Exhaust system restricted-Refer to Restricted Exhaust Restricted Exhaust.
* Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis Testing and Inspection.
* Engine mechanical condition, for example, worn timing chain and gears 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.