Buick Regal: 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

This 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.

Diagnostic Aids

Inspect for any of the conditions listed below:

• If equipped with a key type ignition system, a partially retracted or folded over ignition key. When attempting to start the engine, the mechanical portion of the vehicle key must be locked in the fully extended position with the fob parallel to the key. Leaving the key partially retracted or folded over when starting may interrupt transponder authentication and result in an intermittent no-start condition. In such instances, DTC B3055 may also be set. If an intermittent no-start complaint is received, it may be necessary to discuss with the customer their starting habits and verify they are locking the key in the fully extended position, fob parallel to the key, before starting.
• A crankshaft position sensor condition. When this condition is present, the engine control module (ECM) uses the camshaft position sensors to determine engine speed and position. If the condition exists in the signal circuit of the sensor, 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.

  However, 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.

• An in-tank fuel pump condition. 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. 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. Refer to Fuel Injector Diagnosis and Fuel Injector Circuit Diagnosis for diagnosis.
• Fuel injector ON time inadequate. When this condition is present, 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 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.

• Loose unsecured engine electrical grounds. Inspect the engine for good secure electrical grounds.
• Water or foreign material in the fuel, which can cause either a no start or a 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.
• An ignition system that is susceptible to moisture. An engine that starts and runs after being brought into a warm, dry repair shop, may be susceptible to moisture. Spray water on the ignition system components and wiring while cranking the engine in order to check for an engine starting or will not stay running concern.

Reference Information

Schematic Reference

Engine Controls Wiring Schematics (LTG)

Connector End View Reference

Component Connector End View Index

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Starting System Description and Operation

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 26792 HEI Spark Tester

For equivalent regional tools, refer to Special Tools (Diagnostic Tools) and Special Tools (Mechanical Tools).

Circuit/System Verification

NOTE:

This diagnostic assumes the following:

• The battery is completely charged.
• The engine cranking speed is acceptable.
• There is adequate fuel in the fuel tank.

1. Crank the engine for up to 15 s.

2. Verify that P0201 - P0204, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P1248, P1249, P124A, P124B, P2147, P2148, P2150, P2151, P2153, P2154, P2156, P2157, P0335, P0336, P0351 - P0354, P0601, P0602, P0603, P0604, P0606, P0607, P060E, P062F, P0685, P0689, P0690, P069E, P1516, P1682, P2610, or P2635 is not set.

• If any of the DTCs are set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle.

• Go to next step: If none of the DTCs are set

3. Ignition ON.

4. Verify the security indicator on the instrument panel cluster illuminates momentarily.

• If the indicator stays ON or is flashing

Refer to Diagnostic Trouble Code (DTC) List - Vehicle and Immobilizer Description and Operation.

• Go to next step: If the indicator does not stay ON and is not flashing

5. Verify the scan tool Engine Speed parameter is greater than 0 RPM while cranking the engine.

• If 0 RPM

Refer to DTC P0335 or P0336 for further diagnosis.

• Go to next step: If greater than 0 RPM

6. Ignition OFF.

7. Disconnect a T8 ignition coil from a cylinder and spark plug.

8. Connect a J 26792 HEI Spark Tester between the boot of the ignition coil and ground.

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

9. Verify that the spark tester sparks while cranking the engine.

• If the spark tester does not spark

Refer to Electronic Ignition System Diagnosis for further diagnosis.

• Go to next step: If the spark tester sparks

10. Ignition ON.

NOTE:

• If the engine is too hot, high fuel pressure readings may result due to hot soak fuel boiling. Allow the engine coolant temperature to cool to less than 60º C (150º F) before attempting to verify fuel pressure.
• The Fuel Pump Enable may need to be commanded On a few times in order to obtain the highest possible fuel pressure.
• Additional DTCs may set when using the fuel pump output control.

11. Command the Fuel Pump Enable On several times with a scan tool.

12. Verify that the scan tool Fuel Pressure Sensor parameter is between 345 - 650 kPa (50 - 94 psi) while the fuel pump is running.

• If not within the specified range

Refer to Fuel System Diagnosis.

• Go to next step: If within the specified range

13. Verify that the scan tool Fuel Pressure Sensor parameter, after the pump has turned OFF, decreases to less than 600 kPa (87 psi), and does not decrease greater than 34 kPa (5 psi) in 1 minute.

• If not within the specified range

Refer to Fuel System Diagnosis.

• Go to next step: If within the specified range

14. Verify that the conditions listed below do not exist:

• Collapsed or restricted air intake duct to the throttle body
• Restricted air filter
• Gas or coolant fouled spark plugs
• A skewed manifold absolute pressure (MAP) sensor. Refer to DTC P0106
• A skewed engine coolant temperature (ECT) sensor. Refer to DTC P0117, P0118, or P0119
• A restricted exhaust system. Refer to Restricted Exhaust.
• Contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis.
• An engine mechanical condition, for example, worn timing chain and gears or low compression. Refer to Symptoms - Engine Mechanical or Engine Compression Test
  • If a condition exists

    Repair as necessary.

  • Go to next step: If no conditions exist

15. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

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