Ac system BMW 540i 1998 E39 Workshop Manual

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130-72
Fuel Injection
I Oxygen sensors, replacing
4 Four Bosch oxygen sensors (2 precatalytic converter sen-
sors and
2 post-catalytic converter sensors) provide a vary-
ing voltage signal
[0.2 vdc (max. lean) to 0.8 vdc (max. rich)]
to the ME
7.2 ECM representing oxygen content in the ex-
haust gas.
WARNING-
Exhaust manifolds and pipes can be hot enough to cause se-
rious burns. Wear suitable heavy gloves and other appropri-
ate protection.
- Using a special oxygen sensor socltet, remove the threaded
sensors from the exhaust system.
- If not already applied, coat the new oxygen sensor threads
with an anti-seize compound before installation. Do not get
compound on the sensor tip.
Tightening torque
Oxygen sensor to exhaust system
50 Nm (37 ft-lb)
Fuel injectors, removing and installing
The ME 7.2 system uses ball seat type fuel injectors. This de-
sign
prov:des precise seal'ng when the iniector is closed
therebv eiminalinq raw HC (unb~rned fue ) formalion in tne
intake.-~he fuel inkctors areswitched on and off by the ECM
at the ground side.
- Remove plastic cover from above fuel rail. See100 Engine
Removal and Installation.
- Disconnected battery negative (-) cable.
CAUTION-
Prior to disconnecting the battea read the battery discon-
nection cautions given at the front of this manual. See 001
General Warnings and Cautions.
- Remove both ignition coil covers.
Disconnect ignition coil connectors.
Remove left and right ignition coil ground wires,
4 Remove fuel injector loom boxes.
Loosen mounting fasteners
(A).
Disconnect electrical plugs (B and D).

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130-74
I Fuel Injection
Evaporative system pressure leak
diagnosis, overview
The M62 TU engine is equipped wlth an evaporative fuel sys-
tem pressure leak diagnosis system. The main component of
this system is the leakdiagnosis pump (LDP). The function of
the LDP is to pressurize the fuel tank and the evaporative
emission system for the purpose of detecting leaks.
This system iscapable of detecting a
lealcas small as0.5 mm.
The LDP, located in the left rear wheel housing, contains the
following:
Vacuum chamber. Pneumatic pump chamber
DME activated vacuum solenoid
Reed switch (provides switched voltage
feedback signal to
DME).
The vacuum supply line is in the wiring harness from the en-
gine compartment and runs down the driver's side of the vehi-
cle.
The canister vent valve is
~ntegrated into the LDP, which IS
electrically controlled by the ECM. The canister vent valve is
opened to provide fresh air entry into the fuel system only dur-
ing purge operation.
- Purge operation characteristics:
Off idle through full throttle: purge valve opened by pulse
width modulated (PWM) control of the ECM. PWM duty cy-
cle varies by engine operating conditions
(e.g. warm idle,
purge valve opened slightly; cold
idleldecel with engine
temp
< 67" C. purge valve always closed).

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130-75
Fuel Injection
Secondary air injection, overview
The secondary air system pumps ambient air into the exhaust
stream afteracoid engine start to reduce the warm-up time of
the catalytic converters and to reduces HC and CO emis-
sions. The ME
7.2 ECM controls and monitors the secondary
air injection system. The secondary air pump operates at a
starttemperature of between 10°C
(50°F) and 40°C (104°F).
and continues to operate for a maximum of
2 minutes at idle
speed.
The electric air pump draws in ambient air and supplies it to
the
checlc valve. The vacuum vent valve (solenoid) switches
vacuum to open the
checlc valve when activated by the ECM.
Once opened, the checlc
valve allows air to be pumped into
the exhaust stream.
4 The secondary air injection system consists of the following
components:
1. Secondary air pump relay
2. Oxygen sensors
3. Catalytic converters
4. Electric air pump
5. Non-return valve
6. Vacuum vent valve

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160 Fuel Tank and Fuel Pump
General ........................... .I6 0.2
Special tools ........................ .I6 0.2
Fuel pump ......................... .I6 0.3
Fuel tank evaporative control system ..... .I6 0.3
Evaporative system troubleshooting ..... .I6 0.4
Warnings and cautions ................ .I6 0.5
Fuel System Troubleshooting ...... .I6 0.6
Fuel pump fuse and relay .............. .I6 0.6
Operating fuel pump for tests ........... .I6 0.6
Fuel pump electrical circuit, testing ...... .I6 0.7
Fuel pump power consumption, testing ... .I6 0.9
Fuel pressure gauge, installing
(6-cylinder models)
................. .I6 0.1 0
Fuel pressure gauge, installing
(V-8 models) ....................... .I6 0.1 1
Fuel delivery, testing ................ .I6 0.12
Fuel Pump and Fuel Level Sender . . 160-15
Fuel level sender (right side) and
fuel pump. removing and installing
...... 160-15
Fuel level sender (left side).
removing and installing
............... 160-17
Siphon pump. removing and installing .... 160-1 9
Fuel Tank and Fuel Lines .......... 160-20
Fuel tank. draining ................... 160-20
Fuel tank. removing and installing ....... 160-21
Fuel expansion tank. removing
and installing
....................... 160-23
Activated carbon canister I fuel tank
leak detection unit
(LDP or DMTL).
removing and installing ............... 160-24
Running losses (312-way) valve.
removing and installing
............... 160-24

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This repair group covers service information specifically for the fuel supply system. Information on the fuel injection sys-
tem is covered in
130 Fuel Injection.
In the descriptions and procedures given below, engine and
engine management (DME) systems are referred to by man-
ufacturer code. If necessary, see
100 Engine-General for
model year, engine code, and DME applications.
NOTE-
Fuel filter replacement is covered in 020 Maintenance,
Special tools
Some of the procedures in this group require the use of
special tools.
I( Fuel line clamp 13 3 010 (Tool No. BMW 13 3 01 0)
4 Fuel pressure gauge T-fitting with shut-off valve
(Tool No. BMW 13
5 220)

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Fuel Tank and Fuel Pump
Fuel pump
The electric fuel pump is mounted in the fuel tank in tandem
with the right side fuel level sender. The fuel pump delivers
pressurized fuel to the fuel injection system.
A pressure regu-
lator maintains system pressure. The quantity of fuel supplied
exceeds demand, so excess fuel returns to the fuel tank via a
return line. See
130 Fuel Injection for more information.
NOTE-
Fuel pump removal procedures are given under Fuel level
sender (right side) and fuel pump, removing and install-
ing.
Fuel tank evaporative control system
Evaporative control, also referred to as running losses con-
trol, is designed to prevent fuel system evaporative losses
from venting into the atmosphere.
The components of this system allow control and monitoring
of evaporative losses by the on-board diagnostic
(OED II)
software incorporated into the engine control module (ECM).
NOTE-
1997 V-8 models (540i) with Bosch DME M5.2 are not
equipped with an
OBD I1 running losses monitoring system.
Fuel tank evaporative
control system
(models with
DME MS42.0)
4 The main components of the evaporative control system and
their functions:
Fuel overflow
tank acts as a liquidlvapor separator
Carbon canister stores evaporated fuel.
Plumbing ducts vapors from fuel tank to canister and from
canister to intake
manifold.
- Carbon canister purge valve is controlled by enginecontrol
module (ECM).
Running losses or 312-way valve (not shown) shunts ex-
cess fuel volume directly
back to fuel tank before it circu-
lates through injector fuel rail (models with Siemens MS42
or Bosch M5.2.1 engine management only).
Leak detection unit (LDP or DMTL) pressurizes fuel
tank
and evaporative system to monitor system leaks (models
with Siemens MS42 or Bosch M5.2.1 and later).
Leak detection systems vary among models and years, and
are further described in
130 Fuel Injection.
NOTE -
"3/2-way valve", 'tunning losses valve" and "fuel changeover
valve" are used interchangeably
in BMW technical literature.

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Fuel Tank and Fuel Pump
Evaporative system troubleshooting
- Start by accessing diagnostic trouble codes (DTCs) using a
BMW or BMW compatible aftermarket scan tool.
For purposes of OBD
II emissions compliance, the DME
system sets a diagnostic trouble code (DTC) when it de-
tects a leak that is equal or larger than minimum
lealc
sensed by system.
Malfunction Indicator Light (MIL) is illuminated upon sec-
ond recurrence of fault. See OBD On-Board Diagnostics.
- When leak testing, observe following conditions to obtain
plausible results:
Fuel tank
'1, to 'I., full.
0 Vehicle parked for at least 2 hours to allow fuel to reach
room temperature.
Ideal fuel temperature is 10"- 20°C
(50"
- 68" F).
Do not refuel immediately before
lealc test.
- If a leak is detected, check the following areas:
* Fuel filter cap (leaking or off).
Fuel tank ventilation lines leaking at fuel
tank or activated
carbon canister.
i
Tank ventilation valve leaking (in engine compartment).
Fuel level
sensorlfuel pump cap leaking.
Evaporative system component replacement is covered later
in
th~s group in Fuel Tank and Fuel Lines.

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Fuel Tank and Fuel Pump
Warnings and cautions
Observe the following warnings and cautions when servicing
the fuel system.
WARNING-
* The fuel system is designed to retain pressure even when
the ignition is off. When working with the fuelsystem, loos-
en the fuel lines slowly to allow residual
fuel pressure to
dissipate. Avoid spraying fuel. Use shop rags to capture
leaking fuel.
Before beginning any work on the fuel system, place a
fire extinguisher in the vicinity of the work area.
Fuel is highly flammable. When working around fuel, do
not disconnect any wires that could cause electrical
sparks. Do not smoke or worknearheaters or other fire
hazards.
* Always unscrew the fuel tank cap to release pressure
in the
tanlc before working on the tank or lines.
When disconnecting a fuel hose, wrap shop rag around
end of hose to prevent spray of fuel under pressure.
Do not use a work light with an incandescent bulb near
any fuel. Fuel may spray on the hot bulb causing a fire.
0 Make sure the worlc area is properly ventilated.
CAUTION-
- Prior to disconnecting the battery, read the battery discon-
nection cautions given in
001 General Cautions an4
Warnings.
Before
making any electrical tests with the ignition
turned on, disable the ignition system as described in
120 Ignition System. Be sure the battery is discon-
nected when replacing components.
To prevent damage to the ignition system or other DME
components, including the engine control module
(ECM), always connect and disconnect wires and test
equipment with the ignition off.
Cleanliness is essential when
worl~ing with the fuel sys-
tem. Thoroughly clean the fuel line unions before dis-
connecting any of the lines.
Use only clean tools. Keep removed parts clean and
sealed or covered with a clean, lint-free cloth, especial-
ly if completion of the repair is delayed.
Do not move the car while the fuel system is open.
Avoid using high pressure compressed air to blow out
lines and components. High pressure can rupture inter-
nal seals and gaskets.
Always replace seals, O-rings and hose clamps.

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.-- -
/ Fuel Tank and Fuel Pump - .. -. -- 1
Fuel pump fuse and relay
Troubleshooting of any fuel pump fault should begin with
checking the fuel pump fuse and the fuel pump relay. The
DME main relay should also be checked. The fuel pump relay
is located behind right side luggage compartment interior
panel.
I Fuel pump relay
BLU =blue ERN = blo$,m GRN =groan GRY = grsy ORG =orange PNI< =pink RED =red VIO =violel WHT = wlilte
rk-; I I 1 ECM
I I I 31 8 ,._--___.I
NOTE-
Special tools are required for some of the tests described
here.
4 Fuel pump circu~t is fuse-protected.
0 6-cylinder models with Siemens DME MS41 .I, MS42, V-8
models with Bosch DME M5.2, M5.2.1 englne manage-
ment: Fuse
F54,15A (luggage compartment fuse panel)
6-cylinder models with Siemens DME MS43 engine man-
agement: Fuse
F22,25A (glove compartment fuse panel)
V-8 models with Bosch DME M7.2: Fuse F54,25A (lug-
gage compartment fuse panel)
- Fuse 31 in glove compartment fuse panel supplies power to
coil side of fuel pump relay. Engine control module (ECM)
supplies switched ground to relay. During starting, fuel pump
runs as long as ignition switch is in START position and con-
tinues to run once engine starts. If electrical system fault in-
terrupts power to fuel pump, engine will not run.
. .
Operating fuel pump for tests
- To operate fuel pump for testing purposes without having to
run engine, bypass fuel pump relay to power pump directly.
< To run fuel pump, open luggage compartment and release
right side trim panel.

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Fuel Tank and Fuel Pump
Fuel delivery,
testing
Checitino fuel delive~ is a fundamental oart of troubleshoot- .. ing and diagnosing thk DME system. ~ukl pressure directly
influences
fuel delivery. An accurate fuel pressure gauge will
be needed to make the tests.
There are two significant fuel deliveryvalues to be measured:
* System pressure - created by fuel pump and maintained
by pressure regulator
Residual pressure
- pressure maintained in closed sys-
tem after engine and fuel pump are shut off
if proper system pressure and residual pressure are present,
also check for problems in fuel delivery volume, which can be
affected by restrictions such as clogged fuel filter or fuel pick-
up port in the fuel tank.
System pressure, testing
1. Fuel pressure regulator outer seal
4 System pressure is created by the fuel pump and maintained
2. Vacuum line connection.
3. Fuel pressure regulator Inner seal.
4. Fuel flow back to fuel tank.
5. Fuel flow from fuel pump.
Fuel pressure
regulator
Fuel pressure regulator locations
M52 In fuel injector rail, in engine
compartment
M52 TU In 312 way valve, below vehicle under
driver seat
by the pressure
regulator. System pressure is not adjustable.
M54 In fuel filter
M62 to 9/97 In fuel injector rail, in engine
compartment
M62 from 9/97 to 9/98 In 312 way valve, below vehicle under
driver seat
M62 TU from 9/98 In fuel filter, below vehicle under driver
seat