Engine Cranks But Does Not Run
Engine Cranks but Does Not RunDescription
The diagnostic table identities a condition that causes an engine to not start. The diagnostic table directs the service technician to the appropriate system diagnosis. The diagnostic table assumes the following conditions are met:
- The battery is completely charged.
- The engine cranking speed is within specification.
- There is adequate fuel in the fuel tank.
Diagnostic Aids
Inspect for 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 Coil Test and Fuel Injector Balance Test with Tech 2.Component Tests and General Diagnostics
- 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 PCM 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 malfunctioning EFI relay, also called ENGINE CONTROL relay, or a malfunctioning fuel pump relay can cause a no start. Inspect the each relay for the following conditions:
- Check the electrical resistance of the relay. The resistance across the coil side terminals is 65-95 ohms at 20°C (68'F). Measure for infinite resistance across the switch side terminals.
- The relay electrical contacts may be pitted or sticking. Replace the relay if tapping gently on the relay or wiggling the relay causes a change in the relay's operation.
- The performance of the relay may be affected by temperature. Test the relay after sitting outside overnight and after running the engine 30 minutes.
- The mass air flow (MAF) is compared to a calculated mass air flow based upon the manifold absolute pressure (MAP), the throttle position (TP), and the engine RPM. A skewed or unresponsive MAP sensor at key on will cause the predicted air flow value to be inaccurate. Compare the MAP and TP readings to that of a known good vehicle.
- A faulty engine coolant temperature (ECT) sensor. Use a scan tool in order to compare the ECT with the intake air temperature (IAT) on a completely cooled engine. The ECT should be within 3°C (5°F) of the IAT.
- An intermittent malfunction may be caused by fault in any of the critical information or component electrical circuits. Inspect the wiring harness and the components for an intermittent condition. Refer to Intermittent Conditions.Symptom Related Diagnostic Procedures
Use the following relay cavity table in order to locate the correct cavities to probe during diagnosis. The table layout corresponds to the cavity layout of the relay block, with the bottom of the table representing the front of the vehicle.
Test Description
Engine Cranks But Does Not Run 1 Of 3:
Engine Cranks But Does Not Run 2 Of 3:
Engine Cranks But Does Not Run 3 Of 3:
The number below refers to the step number on the diagnostic table.
4 If a DTC B0576 is present, the EFI relay, also called ENGINE CONTROL relay, may be malfunctioning. The EFI relay supplies voltage to the fuel injectors, ignition coils, and other vehicle components. When the EFI relay is not operating properly, a no start condition occurs.