Cranks Normally But Hard To Start - Mazda MX-5 1990 Workshop Manual

F
TROUBLESHOOTING GUIDE
CRANKS NORMALLY BUT HARD TO START - ALWAYS
• Engine cranks at normal speed but requires excessive cranking time (more than 5 sec.) before starting
• Battery in normal condition
[TROUBLESHOOTING HINTS]
CD
Air/Fuel mixture too lean
• Fuel injection control malfunction
(Correction for coolant temperature)
• Low fuel line pressure
• Air leakage
STEP INSPECTION
Check if "00" is displayed on Self-Diagnosis
Checker with ignition switch ON
c::::r page
F-78
@
Air/Fuel mixture too rich
• Air cleaner element clogged
• Airflow meter stuck
@ Poor ignition spark
Yes Go to next step
ACTION
No Malfunction Code No. displayed
Check for cause (Refer to specified
check sequence)
"88" flashes
Check ECU terminal 1 F voltage
Voltage: Approx. 12V
(Ignition switch
ON)
c:7
page F-80
c::::r page F-128
¢
If OK, replace ECU c::::r page F-127
S>
If not OK, check wiring between
ECU and Self-Diagnosis Checker
c::::r page
F-7
2 Check for correct intake manifold vacuum at idle Yes Go to next step
3
4
F-26
Vacuum: More than 450 mmHg (17.7 inHg)
Check if air cleaner element is clean
c:::r
page F-75
Check for correct fuel line pressure at idle
c::::r page
F-103
Fuel line pressure:
265-314 kPa (2.7-3.2 kg/cm\ 38-46 psi)
(Vacuum hose to pressure regulator dis-
connected)
No Check for air leakage of intake air sys-
tem components
c:::r
page F-93
Yes Go to next step
No Replace air cleaner element
Yes Go to next step
No
Low pressure
Check fuel line pressure while pinching
fuel return hose
c:::>
If fuel line pressure quickly in-
c:7
page F-92
creases, check pressure regulator c:::r
page F-111
S>
If fuel line pressure gradually in-
creases, check for clogging be-
tween fuel pump and pressure
regulator
If not clogged, check fuel pump
maximum pressure
CT
page
F-108