Mazda 626 Station Wagon, Workshop Manual

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TROUBLESHOOTING
NO.3 HARD TO START/LONG CRANK/ERRATIC START/ERRATIC CRANK
3 Hard to start/long crank/erratic start/erratic crank
DESCRIPTION
• Starter cranks engine at normal speed but engine requires excessive cranking time before start.
• Battery is in normal condition.
POSSIBLE
CAUSE
• Spark leakage from high-tension leads
• Vacuum leakage
• Poor fuel quality
• Starting system malfunction
• Spark plqg malfunction
• Air leakage from intake-air system
• Erratic signal from CKP sensor
• Air cleaner restriction
• PCV valve malfunction
• Inadequate fuel pressure
• Purge solenoid valve malfunction
• MAF sensor contamination
• Restriction in exhaust system
• EGR valve malfunction
• Malfunction of pressure regulator control (PRC) system
Warning
• Following troubleshooting flow chart contains fuel system diagnosis and repair
procedures. Read following warnings before performing fuel system service:
— Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage.
Always keep sparks and flames away from fuel.
— Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries
or death and damage. Fuel can also irritate skin and eyes. To prevent this, always
complete “BEFORE REPAIR PROCEDURE” and “AFTER REPAIR PROCEDURE”. (See
Section F)
Caution
• Disconnecting/connecting the quick release connector without cleaning it may possibly
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.
Diagnostic Procedure
STEP INSPECTION RESULTS ACTION
1 Inspect for following:
• Vacuum leakage
• Fuel quality (e.g. proper octane,
contamination, winter/summer blend)
• Loose bands on intake-air system
• Cracks on intake-air system parts
• Air cleaner restriction
Are all items okay?
Yes Go to next step.
No Service as necessary.
2
Connect NGS tester to DLC.
Turn ignition switch on.
Retrieve any DTC.
Is any DTC displayed?
Yes DTC is displayed:
Go to appropriate DTC test.
No No DTC is displayed:
Go to next step.
3 Is engine overheating? Yes Go to symptom troubleshooting No.16 for
“Cooling system concerns - Overheating”.
No Go to next step.
4 Inspect for cracks on high-tension leads
Is there any crack on high-tension leads?
Yes Repair suspected high-tension leads.
No Go to next step.
5 Inspect spark plug conditions.
Is spark plug wet, covered with carbon or gray­
ish white? Yes Spark plug is wet or covered with carbon:
Inspect for fuel leakage from fuel injector.
Spark plug Is grayish white:
Inspect for clogged fuel injector.
No Install spark plugs on original cylinders.
Go to next step.
F1-107