Delivery Rate, Checking

Delivery Rate, Checking

- Remove high pressure in fuel system.

CAUTION: Fuel supply line is under pressure. Wear protective goggles and protective clothing to prevent injuries and contact with skin. Before removing from hose connection wrap a cloth around the connection. Then release pressure by carefully loosening the union nut.

Test sequence
- Read safety precautions before beginning work.
- Observe Clean Working Conditions.

NOTE: A second technician is needed for the following task.

- Connect Pressure Gauge with adapter, as shown.
- However, do not connect ends of Hose to fuel rail connector.







- Hold end of Hose in a measuring container.
- Open shut-off valve of pressure gauge. The lever points in direction of flow.
- Switch ignition on.
- Operate Hand held remote starter (jumper). Slowly close shut-off tap, until pressure gauge shows 4 bar fuel pressure. From this point on do not move position of shut-off tap.
- - Do not operate Hand held remote starter (jumper) any more.
- Empty measuring container.
- Operate remote control for 15 seconds.







- Compare quantity of fuel delivered with minimum delivery rate in diagram (cu.cm/15s).

NOTE: Voltage at fuel pump with engine stopped and pump running is approx. 2 volts less than battery voltage.

If minimum delivery rate is not attained:
- Check fuel lines for possible restrictions (kinks) or blockages.

If lines are OK:
- Replace fuel filter.
- Repeat test.

If specified value is again not obtained:
- Fuel Pump (FP) faulty, replace fuel delivery unit.

If delivery rate has been attained but nevertheless you suspect a fuel supply system malfunction (e.g. intermittent failure of fuel supply system)
- Check Fuel Pump (FP) current draw.

Delivery Rate, Checking
- Check current draw of fuel pump as follows:
- Reconnect all disconnected fuel lines.







- Connect a multimeter with electrical current probe to wire of 4-pin connector terminal - 1 - - arrow - from wiring harness to Fuel Pump (FP) unit, right.
- Start engine and run at idle speed.
- Measure current draw of fuel pump. Specified value: max. 11 amps.

If current draw is exceeded:
- Fuel Pump (FP) faulty, replace fuel delivery unit.

NOTE: If malfunction in fuel system is sporadic, test can also be performed during a road test, but a second person is required.