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
The engine cranks but does not run 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.
This diagnostic assumes the system voltage levels are adequate for starter motor operation. Fuel level and fuel quality must be determined for correct 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 Fuel Injector Diagnosis.
* 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 vehicle in good condition.
* 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 - intake or camshaft position sensor - exhaust.
* 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 (D61)
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
* EL 26792 - HEI Spark Tester
* EN 36012-A - Ignition System Diagnostic Harness
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. 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.
Circuit/System Testing
1. Crank the engine for up to 15 s, observe the DTC information with a scan tool. Verify that DTC P0117, P0118, P0122, P0123, P0222, P0223, P0335, P0336, P0513, P0562, P0563, P0601, P0602, P0603, P0604, P0606, P062F, P0633, P0685, P0689, P0690, P1516, P1631, P1682, P16F3, P2101, P2119, or P2610 are not set.
• If any of the DTCs are set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle
• If no DTCs are set
2. Ignition ON.
3. Verify the security indicator on the instrument panel cluster illuminates momentarily.
• If the indicator stays illuminated or is flashing
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle and Immobilizer Description and Operation Immobilizer
• If the indicator does not stay illuminated or is not flashing
4. Verify the scan tool Engine Speed parameter is greater than 0 RPM while cranking the engine.
• If the Engine Speed parameter is 0 RPM
Refer to DTC P0335 or P0336 P0335 for further diagnosis.
• If the Engine Speed parameter is greater than 0 RPM
Note: It may be necessary to secure the EN 36012-A - ignition system diagnostic harness to the spark plug boots with electrical tape.
5. Install the EN 36012-A - ignition system diagnostic harness to the spark plug boots.
6. Connect the EL 26792 - HEI spark tester between the boot of a spark plug wire and ground.
7. Connect the remaining wires to the appropriate cylinders.
Note: An erratic or weak spark is considered a no spark condition.
8. Verify that the spark tester sparks while cranking the engine.
• If the spark tester does not spark
Refer to Electronic Ignition System Diagnosis Electronic Ignition System Diagnosis for further diagnosis.
• If the spark tester does spark
9. Ignition ON, verify the fuel pump turns ON when commanded ON with a scan tool.
• If the fuel pump does not turn ON
Refer to Fuel System Diagnosis Fuel System Diagnosis.
• If the fuel pump does turn ON
10. Ignition OFF, disconnect the harness connector at a Q17 Fuel Injector.
11. Connect a test lamp between the control circuit and the ignition voltage circuit.
12. Verify the injector test lamp flashes while cranking the engine.
• If the injector test lamp does not flash
Refer to Fuel Injector Circuit Diagnosis for further diagnosis Fuel Injector Circuit Diagnosis.
• If the injector test lamp does flash
13. Ignition OFF, install the CH 48027 - digital pressure gauge.
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.
14. Ignition ON, command the fuel pump ON with a scan tool.
15. Verify that the fuel pressure is between 365-414 kPa (53-60 PSI) while the fuel pump is running.
• If the fuel pressure is not within the specified range
Refer to Fuel System Diagnosis Fuel System Diagnosis for further diagnosis.
• If the fuel pressure is within the specified range
16. Verify the following conditions do not exist:
* Collapsed air intake duct to the throttle body
* Restricted or obstructed air filter or air intake system
* Spark plugs 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 DTC P0116 P0116
* A restricted exhaust system. Refer to Restricted Exhaust Restricted Exhaust.
* Contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis Alcohol/Contaminants-in-Fuel Diagnosis.
* Engine mechanical condition, for example, worn timing chain and gears or low compression-Refer to Symptoms - Engine Mechanical Symptoms - Engine Mechanical.
• If a condition is found
Repair as necessary.
• If a condition is not found
17. All OK
Repair Verification
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
Spark Plug Replacement Service and Repair