Fuel Pressure and Residual Pressure Testing

FUEL PRESSURE AND RESIDUAL PRESSURE TESTING





Checking Vacuum Hose to Pressure Regulator
^ Remove throttle pulley cover.
^ Disconnect vacuum hose from pressure regulator.
^ Check for blockage by blowing through hose.

If hose is clear:
- Connect pressure gauge.
If hose is blocked:
- Check hose and connection at intake manifold.
- Clean or replace as required.





Connect Pressure Gauge
^ Fit pressure gauge P/N 9995011 using union P/N 9989725 and adapter P/N 9995479.
^ Connect adapter to valve on fuel distribution manifold, with adapter in locked position (i.e. valve closed).
^ Turn pressure gauge cock towards adapter P/N 9995479.
^ Connect other gauge connection to fuel drainage unit P/N 9812270, P/N 9812273 and P/N 9812282.
^ Unlock adapter (i.e. valve open).
^ Continue with START FUEL PUMP section below.





Start Fuel Pump
^ Remove electrical distribution unit cover.
^ Remove fuel pump relay (position 103 in electrical distribution unit).
^ Connect jumper lead across relay base terminals 1 and 3.
^ Switch ignition ON. Fuel pump should start.
^ Continue with MEASUREMENT OF SYSTEM PRESSURE section below.





Measurement of System Pressure
^ Read system pressure on pressure gauge.

System pressure should be 300 kPa (43.5 psi).

If reading is correct:
- Proceed to: CHECKING THE FUEL FILTER section below.
If reading is too high:
- Proceed to: SYSTEM PRESSURE TOO HIGH section below.
If reading is too low:
- Proceed to: SYSTEM PRESSURE TOO LOW section below.





System Pressure Too High
^ Disconnect jumper lead across relay base terminals 1 and 3.
^ Disconnect return line from pressure regulator.
^ Blow through line towards tank.

If line is clear:
- Try with new pressure regulator and measure system pressure again.
If line is blocked:
- Check for blockage in return line and clean or replace as required. Measure system pressure again.





System Pressure Too Low
^ Clamp return line and check if pressure rises.

CAUTION: Do not allow pressure to exceed 600 kPa (87 psi).

If pressure rises:
- Pump and lines are intact.
- Replace pressure regulator and measure system pressure again.
If pressure does not rise:
- Check the strainer at the fuel pump.
If fuel pump strainer is OK:
- Replace the fuel pump and measure system pressure again.





Checking the Fuel Filter
^ Squeeze the return pipe and check it the pressure rises.

CAUTION: Do not let the pressure rise higher than 600 kPa (87 psi).

If the pressure rises quickly:
- Check the pressure regulator.
- Proceed to : CHECKING PRESSURE REGULATOR, PRESSURE REDUCTION section below.
If the pressure rises slowly:
- Replace the fuel filter.





Checking Pressure Regulator, Pressure Reduction
^ Connect vacuum pump P/N 9995843 to pressure regulator.
^ Purge the regulator.
^ Check that system pressure falls by same amount as regulator pressure.

300 kPa (43.5 psi) - vacuum = system pressure

^ Disconnect hose from vacuum pump.

System pressure should return to 300 kPa (43.5 psi).

If the pressure is OK:
- Check the pressure regulator.
- Proceed to: PRESSURE REGULATOR, INCREASE IN PRESSURE section below.
If the pressure is not OK:
- Replace the pressure regulator.





Checking the Pressure Regulator, Increase in Pressure
^ Connect pressure tester P/N 9985496 and manometer P/N 9995230 to the pressure regulator.
^ Pump up the pressure in the regulator.
^ Check that system pressure rises as much as the increased pressure in the regulator.

300 kPa (43.5 psi) + overpressure = system pressure

^ Disconnect the hose from the pressure tester.

System pressure should return to 300 kPa (43.5 psi).

If the pressure regulator is OK:
- Check the residual pressure.
If the pressure regulator is not OK:
- Replace the pressure regulator.





Checking Residual Pressure
^ Switch ignition OFF.
^ Disconnect jumper lead between relay base terminals 1 and 3.
^ Reinstall fuel pump relay.

System pressure must not fall below 200 kPa (29 psi) in less than 20 minutes.

If pressure is correct:
- Proceed to: DISCONNECTION OF PRESSURE GAUGE section below.
If pressure is incorrect:
- Fault may be due to leakage from injectors, connections, fuel pump non-return valve or lines.
- Repair as required.





Disconnection of Pressure Gauge
^ Switch ignition OFF.
^ START drainage unit.
^ Turn pressure gauge cock to mid-position.
^ Lock adapter (i.e. valve closed).
^ Disconnect adapter from valve.
^ Stop drainage unit.
^ Reinstate equipment.

NOTE: Remember to refit valve safety cap.