Fuel Pressure and Residual Pressure Testing
Special tools: 9812270, 9812273, 9812282, 998 9725, 999 5011, 999 5479Overview
- The fuel pressure and residual pressure can normally be checked in the workshop. A description of how to check fuel pressure and residual pressure while the car is being driven is included in case this is necessary.
Connect Pressure Gauge
- Supplement pressure gauge 999 5011 with nipple 998 9725 and adapter 999 5479 before use.
- Connect adapter to valve on fuel rail, with adapter in locked position (valve closed as in image inset #1).
- Turn pressure gauge cock so it faces adapter 999 5479.
- Connect other pressure gauge connector to fuel draining unit 981 2270981 2273981 2282.
- Unlock adapter (image inset #2 valve open).
^ Continue with test step below.
Starting Fuel Pump
- Remove electrical distribution unit cover.
- Remove fuel pump relay (position 103 in electrical distribution unit).
- Connect jumper cable across relay base terminals 1 and 3.
- Switch on ignition, fuel pump should start.
^ Continue with test step below.
Measuring System Pressure
- Read off system pressure from pressure gauge.
- System pressure should be 285 - 315 kPa.
If system pressure is OK:
^ Proceed to test step below.
If system pressure is incorrect:
^ Try a new pressure regulator.
Checking Residual Pressure
- Switch off the ignition
- Disconnect jumper cable between relay base terminals 1 and 3.
- Reinstall the fuel pump relay.
- System pressure should not fall below 200 kPa in less than 20 minutes.
If the residual pressure is OK:
^ Proceed to test step below..
If pressure is incorrect:
^ Fault may be due to leakage from injectors, connections, fuel pump non-return valve or lines.
^ Repair as necessary.
Disconnecting Pressure Gauge
- Ignition off.
- Start draining unit.
- Turn pressure gauge cock to mid-position.
- Lock adapter (valve closed as in image inset #1).
- Disconnect adapter from valve.
- Stop draining unit.
- Reinstall equipment.
CAUTION: Remember to reinstall valve safety cap.