Mazda MX-5 1990 Workshop Manual page 168

F
TROUBLESHOOTING GUIDE
4
CRANKS NORMALLY BUT WILL NOT START (PARTIAL COMBUSTION) - AFTER WARM-UP
DESCRIP·
TION
• Engine cranks at normal speed but shows partial combustion and will not continue to run after running and
hot soaked
• Battery in normal condition
• Engine starts normally when cold
[TROUBLESHOOTING HINTS)
G)
Air/Fuel mixture too rich
• Fuel injection control malfunction
(Correction for coolant temperature)
-Injector fuel leakage
STEP
INSPECTION
Check if "00" is displayed on Self-Diagnosis
Checker with ignition switch ON
CJ'
page
F-78
------'""- SELECT SW A
~
\u SYSTEM SELECT
~1~J17"'~ ~
1
2 Check if ECU terminal voltages are OK
(2D and 20)
3
F-24
c::::r
page F-129
Connect diagnosis connector terminals F/P and
GND with jumper wire and check for correct fuel
line pressure with ignition switch ON
CT
page F-l03
Fuel line pressure:
265-314 kPa (2.7-3.2 kg/cm2, 38-46 psi)
I~
"
GND F/P
®
Vapor lock
• Fuel pressure not held in fuel line after engine stops
• High RVP (winter) fuel used in warm weather
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
c::> If not OK, check wiring between
ECU and Self-Diagnosis Checker
Yes Go to next step
No Check for cause (Refer to "Check Point
C7'
page F-80
CJ'
page F-128
c::::r
page F-127
L7
page F-7
for Each Terminal")
CJ'
page F-132
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 fuel line and filter
for clogging
If not clogged, check fuel pump
maximum pressure
c::::r
page F-108
High pressure
Check if fuel return hose is clogged or
restricted
¢
If OK, replace pressure regulator
c::> If not OK, repair or replace hose
c::::r
page F-112