BMW X5 Owners & Service Manuals

BMW X5: Fuel System (N62TU)

Fuel Pump With Drive And Line

NOTES ON FUEL PRESSURE CHECK (REFERENCE PRESSURE: ENVIRONMENT)

Feature of this version with ambient pressure:

The connection for the vacuum hose of the fuel pressure regulator is located between the throttle and the air cleaner or on the air cleaner.

Test precondition:

The correct fuel pressure regulator is fitted.

Description of operation:

The control function of the fuel pressure regulator must be guaranteed under all operating conditions. The fuel pump must always be able to generate a higher fuel pressure than the pressure regulated by the pressure regulator.

The injection rate is adjusted by means of the injection time; the injection time is controlled by the DME.

Description of operation: fuel return line

When the engine is at a standstill and the ignition key is in position 0, the fuel return line after the pressure regulator is at zero pressure.

Description of operation: pressure retaining function

The pressure regulator closes when the engine is at a standstill and the ignition key is in position 0. The fuel pressure in the delivery line is retained over an extended period. A non-return valve closes in the fuel pump.

These measures help to retain the fuel pressure in the fuel system. Extended starting times are thus avoided.

Complaint: drive characteristic faults, lack of power

If the measured value is less than the nominal value - 0.2 bar:

If the measured value is greater than the nominal value + 0.2 bar:

If measured value remains too high, then pressure regulator is in all probability faulty.

IMPORTANT: With less likelihood, the return line may be completely blocked. When the pressure regulator is removed, fuel could escape under pressure!

Complaint: starting problems

If the measured value has dropped by more than 0.5 bar:

If the measured value has now dropped by less than 0.5 bar, the following faults can be present:

If the measured value has dropped by more than 0.5 bar again:

NOTE:

CHECKING FUEL PUMP DELIVERY PRESSURE (N62TU2)

Special tools required:

Necessary preliminary tasks:

IMPORTANT: Fuel in fuel lines is under pressure (approx. 3-5 bar)! Catch and dispose of escaping fuel.

Remove dust cap on measuring valve of fuel rail.

Unscrew non-return valve (1) on special tool kit 13 5 220.

Mount special tool kit 13 5 220 on fuel rail and tighten knurled nut until hand-tight.

Start engine.

Screw in non-return valve (1) until a pressure reading is indicated on the DIS Tester.

Fuel Pump With Drive And Line
Fig. 1: Identifying Special Tool

IMPORTANT: Do not under any circumstances screw in the check valve up to the mechanical stop. This could damage the valve in the fuel rail.

Measuring fuel pressure:

Test Pressure:

INJECTORS AND LINES, FUEL PRESSURE REGULATOR N62 / N45 / N46

Fuel Pump With Drive And Line

Switch off engine.

Assemble vehicle and check fuel system for leaks.

Checking fuel pump:

Remove fuel pump relay.

Connect special tool 61 3 050 to terminal (87) and terminal (30).

Operate button and read off fuel pump delivery pressure at DIS Tester.

Fuel Pump With Drive And Line
Fig. 2: Identifying Special Tool And Terminals

Notes on FUEL PRESSURE CHECK.

Installation:

Now clear the fault memory.

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