)
- Disconnect the high-pressure fuel hose at the delivery pipe side.
)
- Assemble the fuel pressure measurement tools as follows.
- Remove the union joint and bolt from the special tool Adaptor hose (MD998709) and attach the special tool Hose adaptor (MD998742) to the adaptor hose.
- Via a gasket, install the special tool Fuel pressure gauge set (MB991637) into the special tool that has already assembled as described in (a) above.
- Remove the union joint and bolt from special tool Adaptor hose (MD998709) and attach the special tool Hose adaptor (MD998742) to the adaptor hose.
- Via a suitable O-ring or gasket, install the fuel pressure gauge to the special tool that has already assembled as described in (a) above.
<When using the fuel pressure gauge set (special
tool)>
<When using the fuel pressure gauge>
)
- Install the assembled fuel pressure measurement tools between the fuel rail and fuel high-pressure hose.
CAUTION- Connect the MUT-II/III to the diagnosis connector.
- Turn the ignition switch to "ON" position (But do not start the engine).
- Select "Item No. 07" from the MUT-II/III Actuator test to drive the fuel pump. Check that there are no fuel leaks from any parts.
- Finish the actuator test or turn the ignition switch to "LOCK" (OFF) position.
- Start the engine and run at idle.
- Measure fuel pressure while the engine is running at idle.
Standard value: Approximately 270 kPa
)
- Disconnect the vacuum hose from the fuel pressure regulator and measure fuel pressure with the hose end closed by a finger.
Standard value: 330 -
350 kPa
- Check to see that fuel pressure at idle does not drop even after the engine has been raced several times.
- Racing the engine repeatedly, hold the fuel return hose lightly with fingers to feel that fuel pressure is present in the return hose.
NOTE: If the fuel flow rate is low, there will be no fuel pressure in the return hose.
- If any of fuel pressure measured in steps 10 to 13 is out of specification, troubleshoot and repair according to the table below.
| Symptom |
Probable cause |
Remedy |
|---|---|---|
|
Clogged fuel filter |
Replace fuel filter |
| Fuel leaking to return side due to poor fuel regulator valve seating
or settled spring |
Replace fuel pressure regulator |
|
| Low fuel pump delivery pressure |
Replace fuel pump |
|
| Fuel pressure too high |
Binding valve in fuel pressure regulator |
Replace fuel pressure regulator |
| Clogged fuel return hose or pipe |
Clean or replace hose or pipe |
|
| Same fuel pressure when vacuum hose is connected and when disconnected |
Damaged vacuum hose or Clogged nipple |
Replace vacuum hose or clean nipple |
- 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 |
Probable cause |
Remedy |
|---|---|---|
| Fuel pressure drops gradually after engine is stopped |
Leaky injector |
Replace injector |
| Leaky fuel regulator valve seat |
Replace fuel pressure regulator |
|
| Fuel pressure drops sharply immediately after engine is stopped |
Check valve in fuel pump is held open |
Replace fuel pump |
- Release residual pressure from the fuel pipe line (Refer to
).
CAUTION- Remove the fuel pressure gauge and special tool from the delivery pipe.
- Replace the O-ring at the end of the fuel high pressure hose with a new one. Furthermore, apply engine oil to the new O-ring before replacement.
- Fit the fuel high pressure hose over the delivery pipe and tighten the bolt to specified toque.
Tightening torque: 5.0 ±
1.0 N·m
- Check for any fuel leaks by following the procedure in step 7.
- Disconnect the MUT-II/III.