FUEL PRESSURE TEST

1.Release residual pressure from the fuel pipe line to prevent fuel gush out (Refer to ). 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.

2.Disconnect the high-pressure fuel hose at the delivery pipe side.

3.Assemble the fuel pressure measurement tools as follows. <When using the fuel pressure gauge set (special tool)> 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 or MB991981) into the special tool that has already assembled as described in (a) above. <When using the fuel pressure gauge> 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. 4.Install the assembled fuel pressure measurement tools between the fuel rail and high-pressure fuel hose. caution To prevent damage to the M.U.T.-III, always turn the ignition switch to the LOCK (OFF) position before connecting or disconnecting the M.U.T.-III. 5.Connect the M.U.T.-III to the diagnosis connector. 6.Turn the ignition switch to ON position (But do not start the engine). 7.Select "Item No. 07" from the M.U.T.-III actuator test to drive the fuel pump. Check that there are no fuel leaks from any parts. 8.Finish the actuator test or turn the ignition switch to LOCK (OFF) position. 9.Start the engine and run at idle. 10.Fuel pressure measurement while the engine is running at idle. Standard value: Approximately 256 kPa at curb idle

11.Disconnect the vacuum hose from the fuel pressure regulator and measure fuel pressure with the hose end closed by a finger. Standard value: 325 - 335 kPa at curb idle 12.Check to see that fuel pressure at idle does not drop even after the engine has been raced several times. 13.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. 14.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 Fuel pressure too low Fuel pressure drops after racing No fuel pressure in fuel return hose 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 15.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 16.Release residual pressure from the fuel pipe line (Refer to ). 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. 17.Remove the fuel pressure gauge and special tool from the delivery pipe. 18.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. 19.Fit the fuel high pressure hose over the delivery pipe and tighten the bolt to specified toque. Tightening torque: 5 ± 1 N·m 20.Check for any fuel leaks by following the procedure in step 7. 21.Disconnect the M.U.T.-III.