Cranks Normally But Will Not Start (Partial Combustion) - Mazda MX-5 1990 Workshop Manual

F
TROUBLESHOOTING GUIDE
3 CRANKS NORMALLY BUT WILL NOT START (PARTIAL COMBUSTION) - WHEN ENGINE IS COLD
DESCRIP-
TION
• Engine cranks at normal speed but shows partial combustion and will not continue to run
• Battery in normal condition
• Fuel in tank
[TROUBLESHOOTING HINTS]
CD
Air/Fuel mixture too rich
• Air cleaner element clogged
• Airflow meter stuck
@
Air/Fuel mixture too lean
• Fuel injection control malfunction
(Correction for coolant temperature)
• Low fuel line pressure
• Air leakage of intake air system
STEP INSPECTION
2
3
Check if "00" is displayed on Self-Diagnosis
Checker with ignition switch ON
SELECT SW A
L7'
page F-78
Check if strong blue spark is visible at each
disconnected high-tension lead while cranking
engine \ \
~
' . • 0 _ "
~\
Connect diagnosis connector terminal F/P and
GND with jumper wire and check for correct fuel
line pressure with ignition switch ON
u
page F-103
Fuel line pressure:
265-314 kPa (2.7-3.2 kg/cm\ 38-46 psi)
~
kJJI~
GND F/P
4 Check if ECU terminal voltages are OK
(20, 20 and 20)
®
Low engine compression
ACTION
Yes Go to next step
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)
~
If OK, replace ECU
¢
If
not
OK,
check wiring between
ECU and Self-Diagnosis Checker
Yes Go to next step
No Check ignition system (Refer to
L7'
page F-80
L7'
page F-128
c:=r
page F-127
c:::r page F-7
Troubleshooting "Misfire")
L7'
page G-18
Yes Go to next step
No Low pressure
Check fuel line pressure while pinching
fuel return hose
¢
If fuel line pressure quickly in-
creases, check pressure regulator c:=r page F-111
¢
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
u
page F-108
High pressure
Check if fiJel return hose is clogged or
restricted
~
If OK, replace pressure regulator
c:::r page F-112
c:::;;>
If not OK, repair or replace
Yes Go to next step
c:=r page F-129 No Check for cause (Refer to "Check Point
for Each Terminal")
L7'
page F-132
F-22