Subaru Legacy 2003 Service Manual page 1954

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
5 CHECK FUEL PRESSURE.
After connecting pressure regulator vacuum
hose, measure fuel pressure.
Is the measured value within the specified
value?
Warning:
Before removing the fuel pressure gauge,
release fuel pressure.
NOTE:
•If the fuel pressure does not increase,
squeeze fuel return hose 2 to 3 times, then
measure fuel pressure again.
•If out of specification as measured at this
step, check or replace the pressure regulator
and pressure regulator vacuum hose.
6 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1) Start the engine and warm-up completely.
2) Read the data of engine coolant tempera-
ture sensor signal using Subaru Select
Monitor.
Does the measured value exceed the spec-
ified value?
NOTE:
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4DOSTC)-26, Subaru Select Monitor.>
7 CHECK INTAKE MANIFOLD PRESSURE
SENSOR.
1) Start the engine and warm-up engine until
coolant temperature is greater than 60°C
(140°F).
2) Place the shift lever in neutral position.
3) Turn the A/C switch to OFF.
4) Turn all accessory switches to OFF.
5) Read the data of intake manifold pressure
sensor signal using Subaru Select Monitor.
NOTE:
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4DOSTC)-26, Subaru Select Monitor.>
Is the measured value within the specified
value?
Value
206 — 235 kPa (2.1 — 2.4 kg/
2
cm , 30 — 34 psi)
60°C (140°F)
Ignition ON 73.3 — 106.6 kPa
(550 — 800 mmHg, 21.65 —
31.50 inHg) Idling 24.0 — 41.3
kPa (180 — 310 mmHg, 7.09
— 12.20 inHg)
EN(H4DOSTC)-115
ENGINE (DIAGNOSTICS)
Yes
Go to step 6. Repair the follow-
ing items.
Fuel pressure too
high
• Faulty pressure
regulator
• Clogged fuel
return line or bent
hose
Fuel pressure too
low
• Faulty pressure
regulator
• Improper fuel
pump discharge
• Clogged fuel sup-
ply line
Go to step 7. Replace the
engine coolant
temperature sen-
sor. <Ref. to
FU(H4DOSTC)-
28, Engine Cool-
ant Temperature
Sensor.>
Go to step 8. Replace the mass
air flow and intake
manifold pressure
sensor. <Ref. to
FU(H4DOSTC)-
33, Mass Air Flow
and Intake Air
Temperature Sen-
sor.>
No