FUEL PRESSURE TEST 1.Release residual pressure from the fuel line to prevent fuel spray. (Refer to .) 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.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. 4.Install a fuel pressure gauge on the adapter hose that was set up in step 3. Use a suitable O-ring or gasket between the fuel pressure gauge and the special tool so as to seal in order to prevent fuel leakage at this time.

5.Install the special tool, which was assembled in steps 3 and 4 between the fuel rail and the high pressure hose.

6.Use the scan tool to operate the fuel pump. Check the connections between the fuel pressure gauge and the special tool for leaks. 7.Start the engine and run at idle.

8.Measure fuel pressure while the engine is running at idle. Standard value: Approx. 270 kPa (38 psi) at curb idle

9.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: 330 - 350 kPa (47 - 50 psi) at curb idle 10.Check to see that fuel pressure at idle does not drop even after the engine has been raced several times. 11.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. 12.If any of fuel pressure measured in steps 8 to 11 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 regu- lator

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 dis- connected

Damaged vacuum hose or clogged nipple

Replace vacuum hose or clean nip- ple

13.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 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 im- mediately after engine is stopped

Check valve in fuel pump is held open

Replace fuel pump