Fuel Pressure: Testing and Inspection

FUEL PRESSURE AND RESIDUAL PRESSURE CHECK





Check Vacuum Hose to Pressure Regulator
^ Slack off vacuum hose from pressure regulator.
^ Check hose to be sure that it is not blocked by blowing through it.

If hose is fault free:
- Connect pressure gauge.
If hose is blocked:
- Check hose and nipple and fix fault.

CONNECT PRESSURE GAUGE





Engine Without Quick-Release Coupling
^ Switch Ignition OFF.
^ Connect pressure gauge P/N 9995011 between fuel lead and manifold. Use hose P/N 9995116 and nipple P/N 9995431.
^ Plug free end of gauge with plug P/N 9995266.
^ Set cock on pressure gauge to position 1 (cock should point towards hose P/N 9995116)
^ Proceed to: Start Fuel Pump section below.





Engine With Quick-Release Coupling
^ Switch Ignition OFF.
^ Fit pressure gauge P/N 9995011 with nipple P/N 9989725 and adapter P/N 9995479 before use.
^ If draining unit absent, instead of fitting nipple P/N 9989725, fit hose P/N 9995116 and plug P/N 9995266.
^ Connect draining unit P/N 9812270, 9812273 and 9812282 to nipple 9989725 on pressure gauge.
^ Set cock on pressure gauge 999 5011 to position 3 (cock should point towards adapter 9995479).
^ Remove protective cap on valve which is located on fuel manifold.
^ Connect adapter to valve in locked position (Fig 1 valve closed)
^ Unlock adapter (Fig 2 valve open).
^ Proceed to: Start Fuel Pump section below.

START FUEL PUMP





1994 Models and Earlier:
^ Switch Ignition OFF.
^ Remove fuse No 23 in fuse box on left side of instrument panel.
^ Remove Fuel Pump Relay.
^ Connect a lead between contacts 1 and 3 on relay base. (1993 models and earlier: connect lead between contacts 1 and 2 on relay base.)
^ Switch Ignition ON.
^ Continue with System Pressure Measurement section below.

1995 Models:
^ Switch Ignition OFF.
^ Remove fuse No 1 (11B/1) in central relay unit.
^ Remove Fuel Pump Relay in fuse box on left side of instrument panel position 2.
^ Connect a lead between contacts 1 and 3 on relay base.
^ Switch Ignition ON.
^ Continue with System Pressure Measurement section below.





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

System pressure should read 300 kPa (3.0 kp/cm2) (43.5 psi).

If system pressure is OK:
- Proceed to: Check Fuel Filter section below.
If system pressure is too low:
- Proceed to: System Pressure Too Low section below.
If system pressure is too high:
- Proceed to: System Pressure Too High section below.





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

NOTE: Pressure must not exceed 600 kPa (6.0 kp/cm2) (87.0 psi).

If pressure rises:
- Pump and lead are fault-free. Test with a new pressure regulator. Measure system pressure again.
If pressure does not rise:
- Check the In-tank Fuel Pump Filter.
If filter OK:
- Change Fuel Pump. Measure system pressure again.





System Pressure Too High
^ Remove lead between contacts 1 and 3 on relay base. (1993 models and earlier: lead between contacts 1 and 2 on relay base.)
^ Remove return lead from pressure regulator. Blow through.

If lead is OK:
- Test with a new pressure regulator. Measure system pressure again.
If lead is blocked:
- Check if return lead fouled or blocked. Clean and change. Measure system pressure again.





Check Fuel Filter
^ Clamp together return lead and check if pressure rises.

NOTE: Pressure must not exceed 600 kPa (6.0 kp/cm2) (87.0 psi).

If pressure rises rapidly:
- Check pressure regulator, loss of pressure.
If pressure rises slowly:
- Change fuel filter.





Check Pressure Regulator, Loss of Pressure
^ Connect vacuum pump P/N 9995843 to pressure regulator.
^ Pump out air from regulator.
^ Check that system pressure at same rate as regulator pressure.

300 kPa - negative pressure = system pressure.

^ Disconnect hose from vacuum pump.
^ System pressure should return to 300 kPa (43.5 psi).

If pressure is OK:
- Check pressure regulator, Increase in pressure.
If pressure is NOT OK:
- Change pressure regulator.

Check Pressure Regulator, Increase in Pressure
^ Connect vacuum pump P/N 9995843 and manometer P/N 9995230 to pressure regulator.
^ Pump up regulator pressure.
^ Check that system pressure rises as same rate as regulator pressure.

300 kPa - negative pressure = system pressure.

^ Disconnect hose from pressure tester.
^ System pressure should return to 300 kPa (43.5 psi).

If pressure is OK:
- Check residual pressure.
If pressure is NOT OK:
- Change pressure regulator.





Check Residual Pressure
^ Switch OFF ignition.
^ Remove lead between contacts 1 and 3 on relay base. (1993 models and earlier: lead between contacts 1 and 2 on relay base.)
^ Reinstall Fuel Pump Relay.

Value should not fall below 200 kPa (29 psi) in less than 20 minutes.

If residual pressure is OK:
- Disconnect pressure gauge.
If residual pressure is NOT OK:
- Incorrect residual pressure can be due to leaks in injection valves. connectors, Fuel Pump non-return valve, or lead. Fix as necessary.

DISCONNECT PRESSURE GAUGE





Engine Without Quick-Release Coupling
^ Switch OFF ignition.
^ Place shop rag under fuel lead to soak up any fuel spillage when pressure gauge is removed.
^ Remove pressure gauge.

NOTE: Any plastic tape on fuel pipes which is removed must be replaced.





Engine With Quick-Release Coupling
^ Switch OFF ignition.
^ Start draining unit.
^ Lock adapter (Fig. 1 valve closed)
^ Set cock on pressure gauge to mid position.
^ If draining unit absent: Place shop rag under quick-release coupling to soak up any fuel spillage when pressure gauge Is removed.
^ Remove adapter from valve.
^ Stop draining unit.
^ Refit components.

NOTE: Do not forget to refit safety cap to valve.