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Engine Cranks But Does Not Run

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    • Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The engine cranks but does not run is an organised 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 : Scan Tool  → Special 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 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 - Inlet 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 workshop. 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 garage 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

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Special Tools

    • CH 48027 Digital Pressure Gauge
    • EN 36012-A Ignition System Diagnostic Harness
    • EL 26792 HEI Spark Tester

For equivalent regional tools, refer to Special Tools .

Circuit/System Verification

Note: This diagnosis assumes the following:

    • The battery is completely charged. Refer to Battery Inspection/Test .
    • The engine cranking speed is acceptable. Refer to Engine Cranks Slowly .
    • 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 00, P0118 00, P0122 00, P0123 00, P0222 00, P0223 00, P0335 00, P0336 00, P0513 00, P0562 00, P0563 00, P0601 00, P0602 00, P0603 00, P0604 00, P0606 00, P062F 00, P0633 00, P0685 00, P0689 00, P0690 00, P1516 00, P1631 00, P1682 00, P16F3 00, P2101 00, P2119 00, or P2610 00 are not set.
    2. ⇒If any of the following DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
  2. Ignition ON, observe the Theft Deterrent LED located in the driver information centre. The LED should be OFF.
    3. ⇒If the LED is ON, or blinking, refer to Symptoms - Theft Deterrent .
  3. Engine cranking, observe the scan tool Engine Speed parameter. The scan tool should indicate an engine speed greater than 0 RPM.
    4. ⇒If the engine speed is 0 RPM, refer to DTC P0335 or P0336

    Note: It may be necessary to secure the EN 36012-A Ignition System Diagnostic Harness to the spark plug boots with electrical tape.

  4. Install the EN 36012-A Ignition System Diagnostic Harness to the spark plug boots.
  5. Connect the EL 26792 HEI Spark Tester between the boot of a spark plug wire and ground.
  6. Connect the remaining wires to the appropriate cylinders.

    7. Note: An erratic or weak spark is considered a no spark condition.

  7. Engine cranking, verify the spark tester sparks.
    8. ⇒If there is no spark, refer to Electronic Ignition System Diagnosis .
  8. Ignition OFF, disconnect the harness connector at a Q17 Fuel Injector.
  9. Connect a test lamp between the control circuit and the ignition voltage circuit. Engine cranking, the injector test lamp should flash.
    10. ⇒If the injector test lamp does not flash, refer to DTC P0201, P0202, P0203, or P0204 .
  10. Ignition OFF, install the CH 48027 Digital Pressure Gauge.

    11. 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.

  11. Ignition ON, command the fuel pump ON with a scan tool. The fuel pressure should be between 365-414 kPa (53-60 PSI).
    12. ⇒If not within the specified range, refer to Fuel System Diagnosis .
  12. Verify the following conditions do not exist:
    13. • Collapsed air inlet duct to the throttle body
    • Air filter and air inlet system for restrictions and obstructions
    • Spark plugs for being gas or coolant fouled
    • A skewed manifold absolute pressure (MAP) sensor.
    • A skewed engine coolant temperature (ECT) sensor.
    • Test the exhaust system for restrictions. Refer to Restricted Exhaust : Diesel .
    • Test the fuel for contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Engine mechanical condition, for example, worn timing belt or low compression. Refer to Symptoms - Engine Mechanical .
         ⇒If you find any of the above conditions, repair as necessary.

Repair Verification

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Spark Plug Replacement

   


© Copyright Chevrolet. All rights reserved
   


© Copyright Chevrolet. All rights reserved