A common part of basic maintenance that often gets overlooked on BMW's is replacing the fuel filter. The fuel filter is responsible for filtering out small impurities such as dirt and rust that over time accumulate in the fuel tank. When the filter gets clogged, it can cause the car to run sluggishly or even not run at all. In this article I will go over the easy steps involved in changing the fuel filter on the 1984-91 BMW E30 3 Series. Keep in mind that this article is specific to my 325is, however the basics are the same for all fuel injected BMW models. Only the locations for the filter are different. If anyone is reading this and cannot locate the filter on the car, feel free to email me at The Pelican Parts Message Center. I can tell you where it is located.
First, run the car until you have less than a quarter tank of fuel left. This will decrease the amount of pressure coming out of the fuel lines when you disconnect them. Now disconnect the battery to decrease the chance of a random spark igniting any raw fuel in the area.
Now, jack up the rear driver's side of the car and firmly support it using a jack stand. Never rely on just a jack to hold the car up. Always use jack stands when you are under the car. Be sure to jack the car up using a re0inforced part of the vehicle's frame. If you don't you could damage the underside of the car, or worse, drive the jack right through the floorboards. (I have seen this before, it's not pretty.) For those of you not familiar with jacking up the car, Wayne's article on jacking is a good reference to read beforehand.
Pelican Tech Article: Jacking up your BMW
Now crawl under the car. Directly in front of the fuel tank, you will sea plastic panel. Remove the screws that hold this panel to the chassis. You will now see the fuel filter. Locate the hose clamp that holds the filter onto it's mounting bracket. Pull the filter off it's mounting bracket and let it hang free out the bottom of the car. Now look for an arrow on the filter. This arrow will indicate the correct position for the new filter to be installed. It's important that you install the filter in the correct orientation. If you don't see an arrow on the old filter, find the fuel line that goes towards the engine. You will need to have the new filter connected so that the arrow is orientated towards the engine.
Now, use two pairs of vise-grips to clamp the fuel lines shut on both sides of the filter. You don't have to use extreme pressure to clamp them shut. Just enough to hold them closed. Take care not to rip or damage the fuel lines. Now, put on some safety goggles. Loosen both hose clamps on either side of the filter and pull the fuel lines off. Be prepared to have some fuel come out of the filter itself. (This is why you should wear the safety goggles. You don't want gasoline in your eyes.
Take the new filter and make sure that the arrow on the side faces the fuel line that goes towards the engine. Now push that fuel line onto the new filter and tighten the hose clamp that holds it in place. Now take the other fuel line from the fuel pump/tank and push it onto the other end of the new filter and tighten the hose clamp to hold it in place.
Now remove the vise-grips that are clamping the fuel lines. This will allow the gas to flow from the tank back through the filter and on through towards the engine. Push the new filter back into the mounting bracket under the car and tighten the hose clamp that holds it to the bracket. Tuck the fuel lines back up inside. Now re-attach the plastic panel that covers the filter and re-install the bolts that hold it in place.
Now lower the car. Re-connect the battery and fill the tank up. When you restart the car, it may take a few times to get it to run. This is normal. Keep in mind that the fuel system is under constant pressure and we just opened it up, introducing air into the fuel lines. It will take a little time for the fuel pump to deliver fuel to the injectors and pump all the air out of the system. Just give it a couple of turns of the key and it should start up.
Well, there you have it - it's really not too difficult at all. If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs. If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one. Your continued support directly affects the expansion and existence of this site and technical articles like this one. As always, if you have any questions or comments about this helpful article, please drop us a line.