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1.Release residual pressure
from the fuel pipe line to prevent fuel gush out (Refer to
).
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2.Disconnect the
high-pressure fuel hose at the delivery pipe side.
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3.Assemble the special tool
called injector test set (MB992076) as shown in the
figure. (1)
Remove the injector installation adapter from the hose.
Remove another hose together with the adapter and remove the
adopter from the remaining hose. (2)
To the hose ends from which each adapter is removed, attach
the special tool quick connector (MB992049) and special tool
hose adapter (MB992001). (3)
Remove the nipple of the bolt of the special tool hose
adapter (MD998709). (4)
Install the special tool prepared in the procedure (3) to
the nipple that was removed together with hose in the
procedure (1) 4.Attach the special tool between
the delivery pipe and fuel pipe pressure hose.
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<Where the fuel pressure
gauge is used>
- Attach the fuel pressure gauge on the
special tool for measuring the fuel pressure via an
appropriate O-ring or gasket.
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<Where the fuel pressure
gauge set is used>
- Attach the special tool fuel pressure gauge
set (MB991981) on the special tool for measuring the
fuel pressure via an appropriate gasket.
- Connect the leads from the fuel pressure
gauge set to the power supply (cigarette lighter
socket) and special tool vehicle communication
interface (V.C.I.) (MB991824).
caution |
Connection and disconnection
of M.U.T.-III should be always performed with
the ignition switch turned to the LOCK (OFF)
position.
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5.Connect the M.U.T.-III to the diagnosis
connector. 6.Turn the ignition switch to the ON
position. (But do not start the engine.) 7.Select
"Item No. 09" of the M.U.T.-III actuator test to drive the
fuel pump. Verify there is no leakage from each section with
the fuel pressure being applied. 8.Finish the
actuator test or turn the ignition switch to the LOCK (OFF)
position. 9.Start the engine and run at
idle. 10.Measure the fuel pressure while the
engine is running at idle. Standard value:
Approximately 324 kPa 11.Check to see that
fuel pressure at idle does not drop even after the engine
has been raced several times. 12.If any of fuel
pressure measured in steps 10 and 11 is out of
specification, troubleshoot and repair according to the
table below.
Symptom
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Probable cause
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Remedy
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- Fuel pressure is too low.
- Fuel pressure drops after
racing.
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Clogged
fuel filter
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Replace
the fuel filter.
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Fuel
leaking to the return side due to poor seating
of the fuel regulator valve in the fuel pressure
regulator or the settled spring.
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Replace
fuel pressure regulator
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Low
fuel pump delivery pressure
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Replace
fuel pump.
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Fuel
pressure is too high.
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Binding
valve in fuel pressure regulator
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Replace
fuel pressure regulator
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13.Stop the engine and check change of fuel
pressure gauge reading. Normal if the reading does not drop
within 2 minutes. If it does, observe the rate of drop and
troubleshoot and repair according to the table
below.
Symptom
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Probable cause
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Remedy
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Fuel
pressure drops gradually after engine is
stopped
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Leaky
injector
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Replace
injector.
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Leaky
fuel regulator valve seat
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Replace
fuel pressure regulator
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Fuel
pressure drops sharply immediately after engine
is stopped
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Check
valve in fuel pump is held open
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Replace
fuel pump.
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14.Release residual pressure from the fuel
pipe line.
caution |
Cover the hose connection with
rags to prevent splash of fuel that could be
caused by some residual pressure in the fuel
pipe line.
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15.Remove the special tool from delivery
pipe. 16.Replace high-pressure fuel hose to
delivery pipe. 17.Check for any fuel leaks by
following the procedure in step 7. 18.Disconnect
the M.U.T.-III.
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