Residual Pressure

1. Disconnect the fuel inlet line at the fuel injector rail.
2. Connect an appropriate fuel pressure gauge with a "T" fitting at the end of the inlet line.
3. Using an extension hose reconnect the fuel inlet to the fuel injector rail.

Fuel Pump Relay Terminal Identification:

4. Remove the fuel pump relay and bridge terminals 6 and 2 of the relay socket with a fused switch.

5. Turn the fused switch (ON) for 10 seconds.

The fuel pressure should rise to 46 - 54 psi. (3.2 - 3.7 bar).

6. Turn the fused switch (OFF).

The fuel pressure should drop slowly to approx. 15 psi and maintain this pressure for approx. 20 minutes.

^ If this residual fuel pressure can not be maintained the following components may be at fault:

a. Leaking fuel supply lines
b. Leaking fuel injectors
c. Faulty fuel pressure regulator
d. Faulty fuel pump check valve

LEAKAGE TESTS

1. Repeat test steps 1 - 4.
2. Turn the fused switch (ON) for 30 seconds.

The fuel pressure should rise to 46 - 54 psi. (3.2 - 3.7 bar).

3. Visually inspect all fuel supply lines for signs of leakage.

Repair detected leaks.

4. Turn the fused switch (OFF)
5. Immediately clamp shut the fuel supply line from the fuel pump before the fuel pressure gauge.

If the fuel pressure is now maintained for 20 minutes the fuel pump check valve is faulty. Replace the fuel pump.

^ If the fuel pressure falls below the specification continue with step 6.

6. Repeat steps 2, 3, 4, 5. Also, immediately clamp shut the fuel return hose after the fuel pressure regulator.

If the fuel pressure is now maintained for 20 minutes the fuel pressure regulator is faulty. Replace the fuel pressure regulator.

If the fuel pressure falls below the specification, remove the fuel injectors and inspect for leakage. Replace as necessary.