Inspection Procedure 1

INSPECTION PROCEDURE 1 : Engine Malfunctions Due to Insufficient Fuel Supply.

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CASE:)
- Fuel injector failed.
- Open or shorted fuel injector circuit, or loose connector.
- Bent, twisted or clogged fuel pipe or hose.
- Malfunction of the fuel pump module.

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B
- MB991637: Fuel Pressure Gauge Set
- MD998709: Adaptor Hose
- MD998742: Hose Adaptor

STEP 1. Using scan tool MB991958, read the diagnostic trouble code (DTC).

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.




1. Ensure that the ignition switch is at the "LOCK" (OFF) position.
2. Start up the personal computer.
3. Connect special tool MB991827 to special tool MB991824 and the personal computer.
4. Connect special tool MB991911 to special tool MB991824.
5. Connect special tool MB991911 to the data link connector.
6. Turn the power switch of special tool MB991824 to the "ON" position.

NOTE: When special tool MB991824 is energized, special tool MB991824 indicator light will be illuminated in a green color.

7. Start the M.U.T.-III system on the personal computer.
8. Turn the ignition switch to the "ON" position.
9. Check for MFI system diagnostic trouble code. (refer to, MFI Diagnosis - How to Read and Erase Diagnostic Trouble Code. How to Read and Erase Diagnostic Trouble Code

10. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is any DTC set?

YES: Remove scan tool MB991958 in a reverse of the installation procedure. Refer to, MFI Diagnosis - Diagnostic Trouble Code Chart. Diagnostic Trouble Code Descriptions

NO: Go to Step 2.

STEP 2. Check the fuel pressure.

1. Release residual pressure from the fuel line to prevent fuel spray. (Refer to, On-Vehicle Service - Fuel Pump Connector Disconnection (How to Reduce Pressurized Fuel Lines).

WARNING: To prevent a fire, cover the hose connection with shop towels to prevent splashing of fuel that could be caused by some residual pressure in the fuel pipe line.

2. Disconnect the fuel high-pressure hose at the fuel rail side.
3. Assemble the fuel pressure measurement tools as follows.




4. When using the fuel pressure gauge
a. Remove the union joint and bolt from special tool MD998709 (adaptor hose) and instead attach special tool MD998742 (hose adaptor) to the adaptor hose.
b. Place a suitable O-ring or gasket on assembled special tools MD998709 and MD998742 and install the fuel pressure gauge.
c. Install the assembled fuel pressure measurement tools between the fuel rail and fuel high-pressure hose.




5. When using the special tool MB991637 (fuel pressure gauge set)
a. Remove the union joint and bolt from special tool MD998709 (adaptor hose) and instead attach special tool MD998742 (hose adaptor) to the adaptor hose.
b. Install special tool MB991637 (fuel pressure gauge set) to assembled special tools MD998709 and MD998742 with a gasket.
c. Install the assembled fuel pressure measurement tools between the fuel rail and the fuel high-pressure hose.

6. Turn the ignition switch to the "ON" position.
7. Use scan tool MB991958, check the MFI system Actuator test 07 to drive the fuel pump. Check that there is no fuel leaking from any section when the fuel pump is operating.
8. Stop the fuel pump.
9. Start the engine and run at idle.
10. Measure fuel pressure while the engine is running at idle.

Standard value: Approximately 230 kPa (33 psi) at curb idle




11. Disconnect the vacuum hose from the fuel pressure regulator and measure fuel pressure with the hose end closed with your finger.

Standard value: 289 - 309 kPa (42 - 45 psi) at curb idle

12 Check to see that fuel pressure at idle does not drop even after the engine has been revved several times.
13. Revving the engine repeatedly, hold the fuel return hose lightly with your 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.




14. If any of fuel pressure measured in steps 10 to 13 is out of specification, troubleshoot and repair according to the table.




15. Stop the engine and observe fuel pressure gauge reading.
It is normal if the reading does not drop within two minutes.
If it does drop, observe the rate of droppage and troubleshoot and repair according to the table. Start, then stop the engine.
a. Squeeze the fuel return line closed to confirm leak-down occurs from defective fuel pressure regulator.
b. Squeeze the fuel supply line closed to confirm leak-down occurs from defective fuel pump check valve.
c. If pressure continues to drop with both fuel lines squeezed closed, fuel injector(s) are leaking.




16. Release residual pressure from the fuel pipe line. [Refer to On-vehicle Service - Fuel Pump Connector Disconnection (How to Reduce Pressurized Fuel Lines).]

WARNING: Cover the hose connection with shop towels to prevent splash of fuel that could be caused by some residual pressure in the fuel pipe line.

17. Remove the fuel pressure gauge or special tool MB991637, and special tools MD998709 and MD998742 from the fuel rail.
18. Replace the O-ring at the end of the fuel high-pressure hose with a new one.
19. Fit the fuel high-pressure hose into the fuel rail and tighten the bolts to specified torque.

Tightening torque: 5.0 ± 1.0 N.m (44 ± 9 in-lb)

20. Check for fuel leaks.
a. Use scan tool MB991958 to operate the fuel pump.
b. Check the fuel line for leaks, and repair as needed.

21. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Are the fuel pressure test in good condition?

YES: Go to Step 3.

NO: Remove scan tool MB991958 in a reverse of the installation procedure. Repair or replace damage parts. Then go to Step 6.




STEP 3. Check for bending, twisting or clogging of the fuel pipe or hose.

Q: Are the fuel pipe and hose in good condition?

YES: Go to Step 4.

NO: Remove scan tool MB991958 in a reverse of the installation procedure. Repair or replace the damage fuel pipe or hose. Then go to Step 6.

STEP 4. Check the fuel pump module operation.

1. Turn the ignition switch to the "ON" position.
2. Check the operating of the fuel pump by using scan tool MB991958 to force-drive the fuel pump.




3. If the fuel pump will not operate, check by using the following procedure. If normal, check the fuel pump drive circuit.
a. Turn the ignition switch to the "LOCK" (OFF) position.
b. Remove the rear seat assembly..
c. Remove the service hole cover.
d. Disconnect the fuel pump module connector.
e. When the fuel pump drive connector is attached directly to the battery, check if the sound of the fuel pump operation can be heard.

NOTE: As the fuel pump is an in-tank type, the fuel pump sound is hard to hear. Remove the fuel tank filler tube cap and check from the tank inlet.

f. Check for fuel pressure by pinching the fuel hose with fingertips.
g. Connect the fuel pump module connector.
h. Install the service hole cover.
i. Install the rear seat assembly..

4. Turn the ignition switch to the "LOCK" (OFF) position, and then remove scan tool MB991958 in the reverse order of installation.

Q: Is the fuel pump module operation in good condition?

YES: Then go to Step 5.

NO: Replace the fuel pump module. Then go to Step 6.

STEP 5. Check the inside of the fuel tank for contamination and rust.

1. Drain fuel.
2. Remove the fuel tank.
3. Check the inside of the fuel tank.

Q: Is the fuel tank in good condition?

YES: Install the fuel tank. Go to Step 6.

NO: Replace the fuel filter, and clean the fuel tank and fuel line. Then go to Step 6.

STEP 6. Retest the system.

Q: Is the engine malfunction eliminated?

YES: Finish.

NO: Return to Step 1.