Symptom Related Diagnostic Procedures
INSPECTION PROCEDURE 1: Engine Malfunctions Due to Insufficient Fuel SupplyTROUBLESHOOTING HINTS (The most likely causes for this case:)
- Injectorfailed.
- Open or shorted injector circuit, or loose connector.
- Bent, kinked or clogged fuel pipe or hose.
- Malfunction of fuel pump module.
DIAGNOSIS
Required Special Tools:
- MB991502: Scan Tool (MUT-II)
- MB991637: Fuel Pressure Gauge Set
- MD998709: Adaptor Hose MD998742: Hose Adaptor
STEP 1. Using scan tool MB991502, read the diagnostic trouble code (DTC)
CAUTION
To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Read the DTC.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES: Refer to, Diagnostic Trouble Code Chart.
NO: Go to Step 2.
STEP 2. Check the fuel pressure.
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.
1. Release residual pressure from the fuel line to prevent fuel spray.
2. Disconnect the high-pressure fuel hose at the fuel rail side.
3. Assemble the fuel pressure measurement tools as follows.
4. When using a 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 tool between the fuel rail and high-pressure fuel hose.
5. When using 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 via a gasket.
c. Install the assembled fuel pressure measurement tool between the fuel rail and the high-pressure fuel hose.
CAUTION
To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
6. Connect scan tool MB991502 to the data link connector.
7. Use the 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 270 kPa (38 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: 330 - 350 kPa (47 - 50 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. lf any of fuel pressure measured in steps 10 to 13 is out of specification, troubleshoot and repair according to the table below.
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, observe the rate of drop and troubleshoot and repair according to the table below. 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, injector(s) are leaking.
16. Release residual pressure from the fuel pipe line.
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 high-pressure fuel hose with a new one.
19. Fit the high-pressure fuel hose into the fuel rail and tighten the bolts to specified torque.
Tightening torque: 4.9 ± 1.0 Nm (44 ± 8 in-lb)
20. Check for fuel leaks.
a. Use scan tool MB991502 to operate the fuel pump.
b. Check the fuel line for Jeaks, and repair as needed.
21. Disconnect scan tool MB991502.
Q: Are the fuel pressure test in good condition?
YES: Go to Step 5.
NO: Repair or replace. Then go to Step 3.
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: Repair or replace a defective pipe or hose. Then go to Step 6.
STEP 4. Check the fuel pump module operation.
CAUTION
- To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
- To prevent not to confuse top and bottom of fuel pump relay harness side connector, ensure the triangular mark on the junction block and check the connector.
1. Check the operating of the fuel pump by using scan tool MB991502 to force-drive the fuel pump.
2. 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 instrument panel side cover (driver's side).
c. Remove the fuel pump relay (2), and apply battery voltage to junction block side connector terminal number 4. Check that an operating sound can be heard from the fuel pump.
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 in leL
d. Check for fuel pressure by pinching the fuel hose with fingertips.
e. Install the fuel pump relay (2) and instrument panel side cover (driver's side).
Q: Does the fuel pump module work normally?
YES: Then go to Step 5.
NO: Replace the module. Then go to Step 6.
STEP 5. Check the inside of the fuel tank for contamination and rust.
1. Drain the fuel.
2. Remove the fuel tank.
Q: Is the fuel tank in good condition?
YES: 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: The procedure is complete.
NO: Return to Step 1.