Residual Pressure Test

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.
4. Remove the fuel pump relay and bridge terminals 87 and 30 of the relay socket with a fused switch.

NOTE: Terminal numbers refer to numbers stamped in the body of the relay.

Fuel Pump Relay Diagram:

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

^ The fuel pressure should rise to approx. 47 psi.

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 approx. 47 psi.

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

SPECIFICATIONS:
Fuel Pressure [1] 43 psi.
Fuel Pressure Regulator Operating Range 40 - 47 psi.
Fuel Pump Delivery Rate 30 oz. within 30 sec.
Fuel Pump Residual Pressure [2] Approx. 15 psi.
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[1] Nominal Operating Pressure
[2] After 20 minutes