Fuel Pressure: Testing and Inspection

FUEL PRESSURE TEST




1. Release residual pressure from the fuel line.
2. Disconnect the high-pressure fuel hose at the fuel rail side.

CAUTION: Cover the hose with a shop towel not to let pressurized fuel gush out.

3. Assemble the fuel pressure measurement tools as follows.





1. Remove the union joint and bolt from the special tool (adapter hose MD998709) and instead attach the special tool (hose adapter MD998742) to the adapter hose.
2. Install special tool MB991637 (fuel pressure gauge set) to the adaptor hose via a gasket.
3. Install the special tool, which was assembled in step (1) and (2) between the fuel rail and the high pressure hose.
4. Connect the lead wire of the special tool (fuel pressure gauge set) to the power source (cigarette lighter socket) and to the scan tool (MUT-II).
5. Use the scan tool (MUT-II) to drive the fuel pump and check the special tool connections for leaks.
6. Stop the fuel pump.






1. Remove the union joint and bolt from the special tool (adapter hose MD998709) and instead attach the special tool (hose adapter MD998742) to the adapter hose.
2. Install the fuel pressure gauge to the adaptor hose via a suitable 0-ring or gasket.
3. Install the special tool, which was assembled in step (1) and (2) between the fuel rail and the high pressure hose.







4. Drive the fuel pump as follows.
- Connect the fuel pump check connector terminal 1 to the battery (+) terminal using a jumper wire to drive the fuel pump.
5. Check the fuel pressure gauge and special tool connections for leaks.
6. Disconnect the jumper wire from the fuel pump drive terminal to stop the fuel pump.
4. Start the engine and run at idle.
5. Measure fuel pressure while the engine is running at idle.
Standard value: Approx. 230 kPa (33 psi) at curb idle.




6. Disconnect and plug the vacuum hose from the fuel pressure regulator and measure fuel pressure with the hose end closed by a finger.
Standard value: 289-309 kPa (42-45 psi) at curb idle.

7. Check to see that fuel pressure at idle does not drop even after the engine has been raced several times.
8. 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.




9. If any of fuel pressure measured in steps 5 to 8 is out of specification, troubleshoot and repair according to the table.





10. Stop the engine and observe 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.
11. Release residual pressure from the fuel pipe line.
12. Remove the fuel pressure gauge and special tool from the fuel rail.

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

13. Replace the 0-ring at the end of the fuel high pressure hose with a new one.
14. Fit the fuel high pressure hose into the fuel rail and tighten the bolts to specified torque.
Tightening torque: 5 Nm (3.6 ft.lbs.)
15. Check for fuel leaks.

1. Use scan tool (MUT-II) to drive the fuel pump.
2. Check the fuel line for leaks, repair as needed.
3. Stop the fuel pump.
4. Remove the scan tool.

1. Drive the fuel pump as follows.
- Connect the fuel pump check connector terminal 1 to the battery (+) terminal using a jumper wire to drive the fuel pump.
2. Check the fuel line for leaks, repair as needed.
3. Disconnect the jumper wire from the fuel pump drive terminal to stop the fuel pump.