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:
* The engine control module (ECM) uses the camshaft position (CMP) sensors to determine engine speed and position when there is a crankshaft position (CKP) sensor condition.
* The engine will operate with a CKP sensor condition only if the ECM has stored the learned reference position of the camshafts in memory. With a CKP sensor condition in the signal circuit, the engine will go into a limp home mode after a restart. The ECM then calculates engine speed from one of the CMP sensors.
* The bank 1 intake camshaft position sensor is used by the ECM to determine camshaft to crankshaft relationship in order to control fuel injector and ignition system synchronization. If a condition occurs to the sensor or sensor wiring, the camshaft may not be able to synchronize with the crankshaft and the engine may crank but not run with no DTCs set.
* The fuel pump flow control module (FPCM) controls and monitors the operation of the in-tank fuel pump. If the FPCM detects a fault, a DTC sets in the FPCM. The FPCM will then send a serial data message to the engine control module (ECM) requesting the illumination of the malfunction indicator lamp (MIL).
* 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 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.
* Inspect the engine for good secure electrical grounds.
* 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
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 Programming and Relearning for scan tool information
Special Tools
* CH 48027 - Digital Pressure Gauge
* J 26792 - Spark Tester
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 Testing and Inspection.
* There is adequate fuel in the fuel tank.
1. Crank or start the engine. Observe the DTC information with a scan tool. Verify that DTCs P0116, P0118, P0119, P0335, P0336, P0338, P0351-P0356, P0601, P0602, P0604, P0606, P0627, P0628, P0629, P062B, P0651, P0652, P0653, P069E, P167D, P1629, P1631, P1632, P2105 or U0109 does not set.
• If any of the listed DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
2. Observe the fuel pump control module (FPCM) DTC information with a scan tool. Verify FPCM DTC P0191, P0192, P0193, P0231, P0232, P023F, P025A, P0601-P0604, P0606, P062F, P0641, P064A, P06A6, P1255, P2534, or P2635 is not set.
• If a DTC is set refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
3. Ignition ON, observe the Theft Deterrent parameter with a scan tool. The parameter should display Disabled.
• If Enabled is displayed, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
4. Test the ignition system for spark. Refer to Electronic Ignition System Diagnosis Electronic Ignition (EI) System Diagnosis.
5. Ignition ON, command the in-tank 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 System Diagnosis Fuel System Diagnosis.
6. Ignition ON, observe the FPCM fuel line pressure sensor scan tool parameter. Command an increase in the fuel line pressure with a scan tool. Verify the fuel line pressure increases to greater than 410 kPa (60 psi) as commanded.
• If less than the specified range, refer to Fuel System Diagnosis Fuel System Diagnosis.
7. Disconnect the MAF sensor. The engine control module (ECM) will ignore the MAF sensor and default to the calculated air flow.
• If disconnecting the MAF sensor corrects the condition and the connections are OK, replace the MAF sensor. Refer to Mass Airflow Sensor with Intake Air Temperature Sensor Replacement Service and Repair.
Note: The ECM uses the bank 1 intake camshaft position sensor to determine camshaft to crankshaft relationship in order to control fuel injector and ignition system synchronization. This step determines if the intake camshaft position sensor - bank 1 is the cause of the no start.
8. Ignition OFF, install the Intake Camshaft Position Sensor - Bank 1 into the Exhaust Camshaft Position Sensor - Bank 1 position and the Exhaust Camshaft Position Sensor - Bank 1 into the Intake Camshaft Position Sensor - Bank 1 position and connect the harness connectors.
9. Attempt to start the engine. The engine should start.
• If the engine starts, replace the intake camshaft position sensor - bank 1.
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-Refer to Spark Plug Inspection Testing and Inspection.
* A skewed engine coolant temperature (ECT) sensor-Refer to Temperature Versus Resistance - Engine Coolant Temperature Sensor Temperature Versus Resistance - Engine Coolant Temperature Sensor.
* 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, low compression-Refer to Symptoms - Engine Mechanical Symptoms - Engine Mechanical.
• If you find any of the above conditions, repair as necessary.
Repair Instructions
Camshaft Position Sensor Replacement - Bank 1 (Right Side) Intake Camshaft Position Sensor Replacement - Bank 1 (Right Side) Intake
Repair Verification
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.