Mazda MX-5 1990 Workshop Manual page 187

TROUBLESHOOTING GUIDE
F
STEP
INSPECTION
5 Check if ECU terminal voltages are OK
(20, 20 and 20)
ACTION
Yes Go to next step
c:::r
page F-129 No Check for cause (Refer to "Check Point
6 Check if strong blue spark is visible at each dis-
connected high-tension lead while cranking
engine
~
for Each Terminal")
L7
page F-132
Yes Go to next step
No Check igniti n system (Refer to Trouble-
shooting" isfire")
L7
page
G-18
7 Check for injector operating sound at each injec- Yes
tor at idle
No
8 Check if approx. 12V exists at injector connector Yes Check if injlj3ctor resistance is OK.
(W/R) wire with ignition switch ON
c:::T
page
F-112
9 Check if spark plugs are OK
WEAR AND CARBON BUILDUP
PLUG GAP
1.0-1.1mm
(0.039-0.043 in)
I~~
____
BURNS
~~~~DAMAGEAND
DETERIORATION
DAMAGE
10
Connect diagnosis connector terminals
F/P
and
GND with jumper wire and check for correct fuel
line pressure with ignition switch ON
c:::T
page
F-103
I~
W
GND F/P
11
Try known good ECU and check if condition im-
proves c::r page F-127
Resistance: Approx_ 140
~
If OK,
~heck
wiring between injec-
tor anq ECU
¢
If not
C»K,
replace injector
L?
page F-112
No Check
wiri~g
between main relay and
injector
L?
page
F-7
Yes Go to next istep
No Repair or replace
Yes Go to next step
No
Low pressure
Check fuel line pressure while pinching
fuel return hose
c::>
If fuel line pressure quickly in-
L7
page
G-20
creases, check pressure regulator
L?
page F-111
¢
If fuel line pressure gradually in-
creases, check for clogging be-
tween fuel pump to pressure
regulator
If not clogged, check for fuel pump
maximum pressure c::r page F-108
05UOFX-032
F-43