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 procedure is an organized approach to identify a condition which causes the engine to crank but not start. This diagnostic procedure 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 sensors to determine engine speed and position when there is a crankshaft position sensor condition.
* The engine will operate with a crankshaft position sensor condition only if the ECM has stored the learned reference position of the camshafts in memory. With a crankshaft position sensor condition in the signal circuit, the engine will go into a limp home mode after a hard restart. The ECM then calculates engine speed from one of the camshaft position sensors.
* The fuel pump control module controls and monitors the operation of the in-tank fuel pump. If the fuel pump control module detects a fault, a DTC sets in the fuel pump control module. The fuel pump control module will then send a serial data message to the engine control module (ECM) requesting the illumination of the malfunction indicator lamp (MIL).
* The fuel injectors are calibrated to begin operating when the fuel rail pressure reaches 2 MPa (290 psi) at 20-32°C (68-90°F). This specification will vary when the temperature is outside of this range.
* 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 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 Connector End Views By Name
Description and Operation

* Electronic Ignition System Description Description and Operation
* Fuel System Description Fuel System Description
* Immobilizer Description and Operation Immobilizer

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.
* J 26792 HEI Spark Tester.

Circuit/System Verification

Note: This diagnostic assumes the following:

* The battery is completely charged. Refer to Battery Inspection/Test Battery Inspection/Test.
* There is adequate fuel in the fuel tank.

1. Engine cranking for 15 s, observe the DTC information with a scan tool. Verify DTCs P0116, P0118, P0119, P0191, P0192, P0193, P0231, P0232, P023F, P025A, P0335, P0336, P0351-P0356, P0601, P0602, P0603, P0604, P0606, P06A6, P062B, P062F, P069E, P0627, P0628, P0629, P0641, P064A, P1255, P1631, P2534, P2635, or U0109 are not set.

• If any DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for diagnosis.

2. Ignition ON, observe the Security Indicator on the instrument cluster. The security indicator should illuminate momentarily and then go out.

• If the security indicator 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 additional information, refer to Immobilizer Description and Operation Immobilizer

3. Engine cranking, observe the Engine Speed parameter with a scan tool. The reading should show engine speed greater than 175 RPM.

• If the cranking speed is slow, refer to Engine Cranks Slowly Testing and Inspection.
• If the cranking speed is 0 RPM, refer to DTC P0335 (LF1, LFW, or LFX) P0335 for crankshaft position sensor diagnosis.

4. Disconnect the B75B mass airflow (MAF) sensor and attempt to start the engine. The ECM will ignore MAF sensor input, default to calculated airflow, and the engine should start and run if the MAF sensor is faulted.

• If the engine starts and runs, and the MAF sensor circuits and connections test OK, replace the B75B MAF sensor. Refer to Mass Airflow Sensor with Intake Air Temperature Sensor Replacement Service and Repair.

5. Ignition ON, observe the BARO parameter with a scan tool. Determine your altitude and compare the BARO reading to the Altitude Versus Barometric Pressure Altitude Versus Barometric Pressure table. The reading should be within the range specified.

• If the reading is not within the specified range in the table, refer to DTC P2227-P2230 (LFW) P2227 for further diagnosis.

6. Install the J 26792 HEI Spark Tester between the boot of a spark plug wire and ground.

Note:
* Perform this test on at least one cylinder of each cylinder bank.
* An erratic or weak spark is considered a no spark condition.

7. Engine cranking, verify the spark tester sparks.

• If the spark tester does not spark for any cylinder tested, refer to Electronic Ignition System Diagnosis Electronic Ignition (EI) System Diagnosis.

8. Ignition OFF, install a CH-48027 Digital Pressure Gauge-Refer to Fuel Pressure Gauge Installation and Removal Testing and Inspection.
9. 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) while the fuel pump is running.

• If the fuel pressure is not the specified value, refer to Fuel System Diagnosis (Except China) Fuel System Diagnosis (Except China)Fuel System Diagnosis (China) Component Tests and General Diagnostics.

10. Verify that the following conditions do not exist:

* Collapsed air intake duct to throttle body
* Restricted air filter element
* A skewed engine coolant temperature (ECT) sensor-Refer to DTC P0116 P0116.
* Spark plugs gas or coolant fouled-Refer to Spark Plug Inspection Testing and Inspection and Coolant in Combustion Chamber Coolant in Combustion Chamber.
* Exhaust system restricted-Refer to Restricted Exhaust Restricted Exhaust.
* Fuel contaminated-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.

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

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

Mass Airflow Sensor with Intake Air Temperature Sensor Replacement Service and Repair