Fuel Tank And - BMW 1989-1995 525i Service Manual

F UEL TANK AND FUEL PUMP
160 Fuel Tank and Fuel Pump
160-1
GENERAL
160-1
FUEL TANK AND LINES
160-1
Fuel tank, removing . . . . . . . . . . . . . . . . . . . . . 160-2
Fuel level sende r and fuel pump , removing . . 160-3
Fuel level sender, testing 160-4
FUEL PUMP
160-4
Fuel Pump Fuse and Relay . . . . . . . . . . . . . . . 160-4
Operating Fuel Pump for Tests . . . . . . . . . . . . . 160-5
GENERAL
This repair group covers service information specifically for
the fuel pump , tank, filter, and fuel lines. Information on the
fuel injection system is covered in
130
Fuel lnjectlon-DME.
NOTE-
Fuel filler replacement is also covered in
020 Mainte-
nance Program.
The following cautions and warnings should be obse rved
when servicing the fuel system.
WARNING -
• The luel system is designed to retain pressure
even when the ignition is off. When working with
the luel system. loosen the luel lines sfowly to al-
low residual fuel pressure to dissipate gradually.
Avoid spraying 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 work near
heaters or other fire hazards.
• Always unscrew the fuel tank cap to relea se pres-
sure in the tank before working on the tank or
lines.
• Do not use
a
work light near any fuel. Fuel may
spray onto the hot bulb causing
a
fire.
• Make sure Ihe work area is properly ventilated.
Fuel Pump Tests 160-5
Fuel pump electrical circuit, checking 160-6
Fuel pump delivery pressure and
delivery rate, checking 160-6
Fuel pump power consumption , chec king 160-7
TAB LES
a. Fuel Level Sender Resistances 160-4
b. Fuel Pressure Specifications 160·6
c. Fuel Pump Current 160-7
CAUTlON -
• Before making any electrical tests with the igni·
tion turned on. disable the ignition system
as
de -
scribed in
Ignition System-DME.
Be sure the
battery
is
disconnected when replacing compo -
nents.
• To prevent damage to the ignition system or the
electron ic fuel system components. including the
control unit. always connect and disconnect wires
and test equipment with the ignition off.
• Cleanliness is essential when working with the
tuel system. Thoroughly clean the fuel line unions
before disconnecting any of the lines.
• Use only clean toots. Keep removed components
clean and sealed or covered with
a
clean. tint-tree
cloth. especially if completion of the repair is de-
layed.
• Avoid nearby use of compressed air. and do not
move the car while the fuel system is open.
• Avoid using high pressure compressed air to
blowout lines and compo nents. High pressure
can rupture internal seals and gaskets.
• Always replace seals and O-rings.
FUEL TANK AND LINES
The metal fuel tank is located at the rear of the car benea th
the luggage compartment. The tank capac ity is 81 liters (21.4
gallons). Mounted in the fuel tank are the fuel level sender and
the fuel pump. Connecting lines for the evaporative emission
control system and expansion tank are also attached to the
tank. See Fig. 1.
FUEL TANK AND UNES