Fuel Pressure: Testing and Inspection
1. Reduce the internal pressure of the fuel pipes and hoses.
2. Disconnect the fuel high pressure hose at the fuel rail side.
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.
3. Install the fuel pressure gauge mounting tools.
1. Remove the union joint and bolt from the special tool MD998709 (adapter hose) and instead attach the special tool MD998742 (hose adapter).
2. Place a suitable O-ring or gasket on the assembled special tools MD998709 and MD998742 and install the fuel pressure gauge.
3. Install the assembly between the fuel rail and the high pressure fuel hose.
1. Remove the union joint and bolt from the special tool MD998709 (adapter hose) and instead attach the special tool MD998742 (hose adapter).
2. Install the assembled special tools MD998709 and MD998742 to the special tool MB991637 (fuel pressure gauge set) with a gasket in between.
3. Install the assembled special tools between the fuel rail and the high pressure fuel hose.
4. Connect the scan tool to the data link connector.
5. Turn the ignition switch to ON. (But do not start the engine.)
6. Use the scan tool to operate the fuel pump. Check that there are no fuel leaks from any parts.
7. Finish the actuator test or turn the ignition switch to OFF.
8. Start the engine and let it idle.
9. Measure the fuel pressure during idling.
Standard value: Approx. 270 kPa (38 psi) at curb idle
10. Disconnect the vacuum hose from the fuel pressure regulator, and then measure the fuel pressure while using a finger to plug the end of the hose.
Standard value: 330 - 350 kPa (47-50 psi) at curb idle
11. Check to be sure that the fuel pressure during idling does not decrease even after the engine is raced a few times.
12. Use a finger to gently press the fuel return hose while repeatedly racing the engine, and check to be sure that there is fuel pressure in the return hose also.
NOTE: There will be no fuel pressure in the return hose if there is insufficient fuel flow.
13. If the fuel pressure measured in steps (9) to (12) deviates from the standard value range, check for the probable cause by referring to the table below, and then make the appropriate repair.
14. Stop the engine and check for a change of the value indicated by the fuel pressure gauge. The condition is normal if there is no decrease of the indicated value within two minutes.
If there is a decrease of the indicated value, monitor the speed of the decrease, and, referring to the table below, determine the cause of the problem and make the appropriate repair.
15. Reduce the internal pressure of the fuel pipes and hoses.
16. Disconnect the fuel pressure gauge and the special tools from the delivery pipe.
CAUTION: Because there will be some residual pressure in the fuel pipe line, use a shop towel to cover so that fuel doesn't splatter.
17. Replace the O-ring at the end of the fuel high-pressure hose with a new one.
18. After connecting the fuel high-pressure hose to the fuel rail, tighten the installation bolt at the specified torque.
Tightening torque: 5.0 Nm (3.6 ft.lbs.)
19. Check to be sure that there is no fuel leakage.
1. Use the scan tool to operate the fuel pump.
2. Check the fuel line for leaks, repair as needed.
20. Disconnect the scan tool.