Engine Cranks But Does Not Run
Diagnostic Instructions
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. |
• |
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
Electrical Information Reference
Scan Tool Reference
Control Module References
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. |
- Engine cranking for 15 s, observe the DTC
information with a scan tool. Verify that no DTC is set.
- Ignition ON, observe the scan tool Theft Immobiliser
parameter. The reading should display Disabled.
- Visually inspect the fuel system from the high
pressure pump to the fuel tank for leaks.
- Ignition ON, command the fuel pump ON with a scan
tool. You should hear the fuel pump turn ON.
- Ignition OFF, install the EN 34730-1A
Fuel Pressure Gauge to the fuel supply pipe at the fuel filter
assembly.
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. |
- Ignition ON, command the fuel pump ON with a scan
tool. The fuel pressure should be between 415-535 kPa
(60-78 psi).
- Verify the following conditions do not exist:
• |
Collapsed air inlet duct to the throttle body |
• |
Restricted air filter element |
⇒ |
If you find any of the above conditions, repair as
necessary. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
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