Checks
| Action
|
DEFINITION: Engine
cranks OK, but does not start for a long time. Does eventually run, or may
start but immediately dies.
|
Preliminary
|
| • | Refer to Important Preliminary Checks Before Starting in
Symptoms
. |
|
Sensor/System
|
| • | Test the Engine Coolant Temperature (ECT) sensor for being shifted
in value. Connect a scan tool. Compare the Engine Coolant Temperature against
the Intake Air Temperature (IAT) on a cold engine. The ECT and
IAT sensor values should be within ± 3°C (5°F) of
each other. If the ECT sensor is out of range with the IAT sensor,
test the resistance of the ECT sensor. Refer to Temperature vs Resistance
for resistance specifications.
Replace the ECT sensor if the resistance is not within the specification.
If the sensor is within the specification, repair ECT signal circuit
for high resistance. |
| • | Inspect the Mass Air Flow sensor installation. A MAF sensor that
is incorrectly installed may cause a hard start. Important: The embossed arrows
on the MAF sensor indicate the direction of the intake air flow.
The arrows must point toward the engine. Install the MAF in the
proper direction. Refer to
Mass Airflow Sensor Replacement
. |
| • | The Camshaft Position Sensor (CMP) may cause a long engine crank
time if the PCM does not receive a CMP signal. |
|
Fuel System
|
| • | A faulty in-tank fuel pump check valve allows the fuel in the
lines to drain back to the tank after the engine stops. To test for this
condition, refer to
Fuel System Diagnosis
. |
| • | Inspect both injector fuses for being open. An open injector fuse
causes four injectors and four ignition coils not to operate. Replace the
fuse. Inspect the injector circuits and the ignition coil circuits
for an intermittent short to ground. |
| • | Test for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis
. |
|
Ignition System
|
| • | Inspect both injector fuses for being open. An open injector fuse
causes four ignition coils and four injectors not to operate. Replace the
fuse. Inspect the ignition coil circuits and the injector circuits for
an intermittent short to ground. |
| • | Remove the spark plugs and inspect for the following: |
Refer to
Spark Plug Visual Diagnosis
in Engine Electrical.
|
Engine Mechanical
|
| • | Test for low cylinder compression. Refer to Engine Compression Test
in Engine Mechanical-5.7L.
|
| • | Combustion chambers for excessive carbon buildup. Clean the chambers
using top engine cleaner. Follow the instructions on the can. |
| • | For incorrect basic engine parts. Inspect the following: |
Refer to Engine Mechanical-5.7L.
|
