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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 diagnostic table is an organised approach to identifying a condition that causes an engine not to start. This diagnostic directs the service technician to the appropriate system 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 Balance Test with 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.
    • 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.
    • 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.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Starting System Description and Operation

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

EN 34730-1A Fuel Pressure Gauge

For equivalent regional tools, refer to Special Tools .

Circuit/System Verification

Note: This diagnostic assumes the following:

    • The battery is completely charged. Refer to Battery Inspection/Test .
    • The engine cranking speed should be at least 100 RPM cold and 180 RPM hot. Refer to Engine Cranks Slowly .
    • There is adequate fuel in the fuel tank.
  1. Engine cranking for 15 s, observe the DTC information with a scan tool. Verify that no DTC is set.
    2. ⇒If any DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
  2. Ignition ON, observe the scan tool Theft Immobiliser parameter. The reading should display Disabled.
    3. ⇒If Enabled is displayed, refer to Symptoms - Immobiliser .
  3. Visually inspect the fuel system from the high pressure pump to the fuel tank for leaks.
    4. ⇒If a fuel leak is present, refer to Fuel Leak Diagnosis .
  4. Ignition ON, command the fuel pump ON with a scan tool. You should hear the fuel pump turn ON.
    5. ⇒If the fuel pump does not turn ON, refer to Fuel Pump Electrical Circuit Diagnosis .
  5. Ignition OFF, install the EN 34730-1A Fuel Pressure Gauge to the fuel supply pipe at the fuel filter assembly.

    6. 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.

  6. Ignition ON, command the fuel pump ON with a scan tool. The fuel pressure should be between 415-535 kPa (60-78 psi).
    7. ⇒If not within the specified range, refer to Fuel System Diagnosis .
  7. Verify the following conditions do not exist:
    8. • Collapsed air inlet duct to the throttle body
    • Restricted air filter element
    • A skewed engine coolant temperature sensor. Refer to DTC P0116-P0119 : LNP or LNQ .
    • Exhaust system restricted. Refer to Restricted Exhaust : Diesel .
    • Fuel contamination. Refer to Contaminants-in-Fuel Diagnosis .
    • Engine mechanical condition, for example, worn timing belt or low compression. Refer to Symptoms - Engine Mechanical or refer to Engine Compression Test .
         ⇒If you find any of the above conditions, repair as necessary.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

   


© Copyright Chevrolet. All rights reserved
   


© Copyright Chevrolet. All rights reserved