Subaru Legacy 2004 Service Manual page 897

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
7 CHECK FUEL PRESSURE.
Warning:
• Place "NO FIRE" signs near the working
area.
• Be careful not to spill fuel.
1) Release the fuel pressure.
(1) Disconnect the connector from fuel
pump relay.
(2) Start the engine and run it until it stalls.
(3) After the engine stalls, crank it for five
more seconds.
(4) Turn the ignition switch to OFF.
2) Connect the connector to fuel pump relay.
3) Disconnect the fuel delivery hose, and con-
nect the fuel pressure gauge.
4) Install the fuel filler cap.
5) Start the engine and idle while gear posi-
tion is neutral.
6) Measure the fuel pressure while discon-
necting pressure regulator vacuum hose from
intake manifold.
Warning:
Release fuel pressure before removing the
fuel pressure gauge.
NOTE:
If fuel pressure does not increase, squeeze fuel
return hose 2 to 3 times, then measure fuel
pressure again.
8 CHECK FUEL PRESSURE.
After connecting the pressure regulator vac-
uum hose, measure fuel pressure.
Warning:
Release fuel pressure before removing the
fuel pressure gauge.
NOTE:
• If fuel pressure does not increase, squeeze
fuel return hose 2 to 3 times, then measure
fuel pressure again.
• If the measured value at this step is out of
specification, check or replace pressure regu-
lator and pressure regulator vacuum hose.
9 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 Moni-
tor.
NOTE:
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4SO 2.5)(diag)-26, Subaru Select Mon-
itor.>
Check
Is fuel pressure 284 — 314
kPa (2.9 — 3.2 kg/cm
46 psi)?
Is measured value 206 — 235
kPa (2.1 — 2.4 kg/cm
34 psi)?
Is the engine coolant tempera-
ture between 70#C (158#F) and
100#C (212#F)?
EN(H4SO 2.5)(diag)-138
Yes
Go to step 8.
2
, 41 —
Go to step 9.
2
, 30 —
Go to step 10.
No
Repair the follow-
ing items.
Fuel pressure is
too high:
• Clogged fuel
return line or
bent hose
Fuel pressure is
too low:
• Improper fuel
pump discharge
• Clogged fuel
supply line
Repair the follow-
ing items.
Fuel pressure is
too high:
• Faulty pres-
sure regulator
• Clogged fuel
return line or
bent hose
Fuel pressure is
too low:
• Faulty pres-
sure regulator
• Improper fuel
pump discharge
• Clogged fuel
supply line
Replace the
engine coolant
temperature sen-
sor. <Ref. to
FU(H4SO 2.5)-20,
Engine Coolant
Temperature Sen-
sor.>