Mazda MX-5 1990 Workshop Manual page 211

TROUBLESHOOTING GUIDE
F
STEP
7
INSPECTION
Check for correct fuel line pressure at idle
c:::r page F-103
Fuel line pressure:
265-314
kPa
(2.7-3.2
kg/cm2,
38-46
psi)
(Vacuum hose to pressure regulator dis-
connected)
8 Check for correct ignition timing at idle
c:::r page F-75
Ignition timing: 10 0 ± 1 0 BlOC
~
9
Check if cooling system is OK
c:::r page E-3
10 Try known good ECU and check if condition
improves
L7
page
F-127
ACTION
Yes Check if fuel line pressure decreases
when accelerating quickly
No
¢
If decreases, check for clogging
between fuel pump and pressure
regulator
9
If no decrease, go to next step
Low pressure
Check for fuel line pressure while pinch-
ing fuel return hose
¢
If fuel line pressure quickly in-
creases, check pressure regulator c:::r page F-111
9
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 cr page F-l08
Yes Check if ignition timing advances when
accelerating
No
Yes
No
Yes
No
¢
If advances, go to next step
¢
If no advance, replace ECU
Adjust
Go to next step
Repair or replace
• Thermostat
• Electric cooling fan
• Radiator
Replace ECU
Change fuel to another brand or use
higher octane fuel
c:::r page F-127
cr page
F-75
c:::r page E-8
cr
page B-ll
u
page
E-7
05UOFX-044
F-67