Pre pump and fuel sender remove and install.

NOTE: Not all cars have a pre-pump. If your car does NOT have a fuel pump by the fuel filter, you do NOT have a pre-pump, the pump in the tank is the main pump. These instructions are still valid for removal of this main pump.
Give a sharp upward tug on either side of the front edge of the seat.
Ensure tank is not more than half full, drain off fuel if necessary by removing drain plug in bottom right section of tank.
Remove cover on right side of floor pan
Remove clamps (yellow arrows), hoses and wiring connectors (green arrows) from assembly below right side cover.
Remove four 8mm nuts securing the fuel level sender to the pump assembly.
Lift out fuel sender unit.
CAUTION: Fuel level sender is a canister with a very small drain hole, fuel will spill when it is removed, take appropriate precautions.
Turn remaining assembly counter clockwise to disengage from fuel tank and remove.
As fuel pump assembly is raised, it must be tilted to the side to allow the filter to clear the tank.

Post 1988 models have a second fuel sender on the left side of the fuel tank. Remove the right cover plate on the floor, disconnect wiring and turn assembly counter clockwise to remove.

Installation

Before installing, check resistance value of fuel level sender. Resistance between left and center pins should rise steadily, without breaks, while float moves up in chamber. Resistance between center and right terminals should show open circuit until float hits bottom, when reading should go to approximately 0 Ohms, this is the fuel warning light switch.

Replace seals and hose clamps during installation.

Torques :

Fuel Sender to pump assembly : 1.8 - 2.0 Nm (1.3 - 1.4 ft lbs.)
Hose Clamps : 2 Nm (1.4 ft lbs. )

Part numbers

Fuel level sending unit : 16 14 1 153 266
Pre pump : 16 14 1 179 415

E30 M3 Repair Manual V2.7. Copyright Š1999-2001 Koala Motorsport & Brett Anderson