No.4 Hard To Start/Long Crank/Erratic Start/Erratic Crank[L3 With Tc] - Mazda CX-7 2007 Workshop Manual

SYMPTOM TROUBLESHOOTING [L3 WITH TC]

NO.4 HARD TO START/LONG CRANK/ERRATIC START/ERRATIC CRANK[L3 WITH TC]

4 HARD TO START/LONG CRANK/ERRATIC START/ERRATIC CRANK
• Starter cranks the engine at normal speed but the engine requires excessive cranking time before
DESCRIPTION starting.
• Battery is operating normally
• Vacuum leakage
• Poor fuel quality
• Starting system malfunction
• Erratic signal to ignition coils
• Spark plug malfunction
• Air leakage from intake-air system
• Improper air/fuel mixture ratio control
• Incorrect fuel injection timing
• Erratic signal from CKP sensor
• Erratic signal from CMP sensor
• Front and/rear HO2S sensor or related circuit malfunction
• ECT sensor or related circuit malfunction
• MAF sensor or related circuit malfunction
• Intake-air system restriction
• Improper operation of electronic throttle control system
• PCV valve malfunction
• Inadequate fuel pressure (high or low pressure side)
• Relief valve malfunction (built-in delivery pipe)
• Spill valve control solenoid valve malfunction (built-in high pressure fuel pump)
• Fuel filter clogging
• Fuel line restriction
• Fuel leakage
• Fuel pump (low-side) resister or related circuit malfunction
• Fuel injector malfunction
• Fuel pressure sensor malfunction
POSSIBLE CAUSE
• High pressure fuel pump malfunction
• Exhaust system or three-way catalytic converter restriction
• EGR valve malfunction
• Purge solenoid valve malfunction
• Low engine compression
• Improper valve timing
Warning
The following troubleshooting flow chart contains the fuel system diagnosis and repair
procedures. Read the following warnings before performing the fuel system services:
• Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always
• Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injury or
Caution
• Disconnecting/connecting the quick release connector without cleaning it may possibly
01-03–20
keep sparks and flames away from fuel.
death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete
"BEFORE REPAIR ROCEDURE" and "AFTER REPAIR PROCEDURE" described in this
manual.
(See01-14-4 BEFORE REPAIR PROCEDURE[L3 WITH TC].)
(See01-14-4 AFTER REPAIR PROCEDURE[L3 WITH TC].)
cause damage to the fuel pipe and quick release connector. Always clean the quick release
connector joint area before disconnecting/connecting, and make sure that it is free of
foreign material.
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