Fuel Pump Replacement & M3 Fuel Baffle Fixture DIY

*** Warning ***

You will be dealing with very flammable liquids. Work with windows down, battery disconnected, cell phones away, no smoking, basically don't have anything near your work area that could cause a spark. All pictures were taken with no flash. Also, disconnect the battery before proceeding.  I'm not responsible if you get high on gas fumes or if you cause an explosion and die.

Disconnect the battery

Pop the rear seat by pulling it upwards

Lift the sound deadening material and undo the 4 nuts that hold the fuel pump access lid

Dirty as hell

After some vacuuming it looks much  better. Disconnect the plug and cut the clip that secures the fuel line on pump. We will be using a new one. Fuel will spill until pressure is relieved so be ready with some rags around. I used a bolt to seal the fuel pump hose to prevent more fuel spilling. Then I used a lot of water to wash out the excessive fuel and cleaned the whole area.

Using a hammer and a screwdriver, lightly hit the big round ring until it becomes loose.

After the ring is removed, it's just a matter of carefully lifting the fuel pump out of the tank. I run the car until almost empty for safety reasons. To secure the fuel baffle fixture, I simply dropped it in the tank and clipped it on the right side of that plastic thing which was already inside. There is a hose, I believe it's the fuel return hose, that must be removed from its existing location in the tank and be relocated to the top part of the fuel baffle fixture. When you take a look inside the tank you will understand better.

With the new fuel pump and baffle, I also got a new o-ring. Place the o-ring in place before dropping the new pump inside.

Screw the big metal ring back with light hammer hits, reconnect the fuel hose and secure it with the new clamp

Reconnect the plug, connect the battery and then turn the key to ignition position II, then off, then again on position II so that the pump operates and fills the lines with fuel. Start the car and check for any leaks from the hoses. If everything is ok, re-install everything and enjoy an improved ride.