Engine Cranks But Does Not Run
Diagnostic Instructions
Circuit/System Description
The Engine Cranks but Does Not Run diagnostic table is an
organized 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 System 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 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 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. |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
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 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. |
Ignition ON, observe the scan
tool Theft Immobilizer parameter. The reading should display
Disabled. |
| 3. |
Visually inspect the fuel
system from the high pressure pump to the fuel tank for
leaks. |
| 4. |
Engine cranking for 15 s,
observe the scan tool Fuel Rail Pressure Sensor parameter. The
reading should be greater than 20 MPa (2 900 PSI). |
| 5. |
Verify the following
conditions do not exist: |
| |
• |
Collapsed air intake duct to
the throttle body |
| |
• |
Restricted air filter
element |
| |
• |
Fuel contamination. Refer to
. |
| ⇒ |
If you find any of the above conditions, repair as
necessary. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
|
