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 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).
* 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 (CH47976) Fuel Injector Diagnosis (CH47976)Fuel Injector Diagnosis (J 39021 or Scan Tool) Fuel Injector Diagnosis (J 39021 or Scan Tool).
* 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
Connector End View Reference

Component Connector End Views Connector Views
Description and Operation

* Electronic Ignition System Description Description and Operation
* Fuel System Description Fuel System Description
* Immobilizer Description and Operation (with ATH) Immobilizer Description and Operation (with ATH)Immobilizer Description and Operation (without ATH) Immobilizer Description and Operation (without ATH)

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. See Battery Inspection/Test.
* There is adequate fuel in the fuel tank.

1. Ignition ON, test the fuses that are supplied voltage by the powertrain relay. The test lamp should illuminate for each test point of the fuses.

• If the test lamp does not illuminate for at least one test point of each fuse, refer to DTC P0685, P0689, P0690, or P1682 P0685 for powertrain relay system 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 (with ATH) Immobilizer Description and Operation (with ATH)Immobilizer Description and Operation (without ATH) Immobilizer Description and Operation (without ATH).

3. Engine cranking, observe the scan tool Engine Speed parameter. The parameter should indicate an engine speed greater than 175 RPM.

• If the cranking speed is slow, refer to Engine Cranks Slowly Testing and Inspection.
• If cranking speed is 0 RPM, refer to DTC P0335 P0335 and DTC P0336 P0336 for crankshaft position sensor diagnosis.

4. Ignition ON, observe the ECT Sensor parameter with a scan tool. Compare the parameter reading to the actual engine coolant temperature. The readings should be within ±3°C (±5°F).

• If the temperature readings are not within the ±3°C (±5°F) of each other and the ECT sensor circuits test OK, replace the ECT sensor.

5. Disconnect the mass airflow (MAF) sensor. 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 test OK, replace the MAF sensor.

6. 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, and the barometric pressure sensor circuits test OK, replace the barometric pressure sensor.

7. Ignition OFF, inspect the engine air filter, intake duct, and MAF sensor. The air way should be clear.

• If the intake duct is blocked or collapsed, or the filter is restricted or water saturated, repair or replace as necessary.
• If the MAF sensor is damaged or contains water, replace it.

8. Install the J 26792 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.

9. 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.

10. Collect a fuel sample from the fuel tank. The sample should be bright and clear, free of water, dirt, or other debris. Also, verify the fuel is the correct type for this engine. Refer to Alcohol/Contaminants-in-Fuel Diagnosis Testing and Inspection.

• If the fuel is contaminated with water, dirt, or other debris, replace the fuel filter and refer to Fuel System Cleaning Service and Repair.
• If the fuel is not the correct type, drain the fuel system and the fuel tank and replace with the correct type.

11. Ignition OFF, install a CH-48027 Digital Pressure Gauge-Refer to Fuel Pressure Gauge Installation and Removal Fuel Pressure Gauge Installation and Removal.
12. Ignition ON, command the Fuel Pump Enable ON with a scan tool. Verify the fuel pressure is between 380-520 kPa (55-76 psi).

• If the fuel pump runs but the pressure is not the specified value, refer to Fuel System Diagnosis Fuel System Diagnosis.
• If the fuel pump does not run, refer to Fuel Pump Electrical Circuit Diagnosis Fuel Pump Electrical Circuit Diagnosis.

13. Verify the following conditions do not exist:

* Spark plugs gas or coolant fouled
* Skewed manifold absolute pressure (MAP) sensor
* Skewed engine coolant temperature (ECT) sensor
* Restricted exhaust system. Refer to Restricted Exhaust Restricted Exhaust Restricted Exhaust.
* Engine mechanical condition, for example, worn timing chain and sprockets or low compression. Refer to Symptoms-Engine Controls.

• 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.

* Air Cleaner Element Replacement (LSA) Service and Repair
* Air Cleaner Resonator Outlet Duct Replacement Service and Repair
* Spark Plug Replacement Service and Repair
* Fuel Tank Fuel Pump Module Replacement - Right Side Fuel Tank Fuel Pump Module Replacement - Right Side for fuel filter replacement which is not serviced separately.
* Mass Airflow Sensor with Intake Air Temperature Sensor Replacement (LSA) Service and Repair
* Barometric Pressure Sensor Replacement Service and Repair
* Engine Coolant Temperature Sensor Replacement Service and Repair