Mazda MX-5 1990 Workshop Manual page 203

TROUBLESHOOTING GUIDE
F
STEP
INSPECTION
15 Check for correct fuel line pressure at idle
c::?
page F-103
Fuel line pressure:
265-314 kPa (2.7-3.2 kg/cm
2
,
38-46 psi)
(Vacuum hose to pressure regulator dis-
connected)
ACTION
Yes Check if fuel line pressure decreases
when accelerating quickly
No
q
If decreases, check fuel pump
maximum pressure
LT
page F-l08
If OK, check fuel line and filter for
clogging
q
If no decreases, go to next step
Low pressure
Check for fuel line pressure while pinch-
i ng fuel retu rn hose
q
If fuel line pres:re quickly in-
creases, check pressure regulator
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page F-lll
¢
If fuel line pressure gradually in-
creases, check for clogging be-
tween fuel pump and pressure
regulator
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page F-112
If not clogged, check fuel pump
maximum pressure
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page F-108
16 Run engine several minutes at idle and check if Yes
fuel line pressure is held after ignition switch
High pressure
Check if vacuum hose to pressure
regulator is damaged or poorly con-
nected
turned OFF
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page F-1 02
Fuel line pressure: More than
147 kPa
(1.5 kg/cm
2
,
21 psi) for 5 min.
PRESSURE
MINIMUM
I~ ~I
IGNITION 5 MIN. TIME
SWITCH OFF
17 Disconnect each injector connector at idle and
check if engine speed decreases equally each
time
18 Try known good ECU and check if condition im-
proves
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page F-127
No
q
If OK, replace pressure regulator
¢
If not OK, repair or replace hose
Check injector for fuel leakage
Yes Go to next step
No Replace injector
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page
F-112
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page F-113
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page F-112
05UOFX-041
F-59