BMW E46 Fuel Pump Test – 2000-2005 325i/325ci – M54 Eng.

As discussed above, testing the fuel pump is actually a two step process. First is making sure the pump is powering up and running and if it is, verifying it is producing the correct fuel pressure in the engine.

1. The BMW E46 fuel pump is located under the rear seat of the vehicle. To access it, grasp the bottom of the rear seat and pull out and up to release it from the body of the car. Use a bungee cord if necessary to safely stow it out of the work area.
2. Lift the sound insulation off of the top of the fuel pump and fold it backwards. You can now access the fuel pump cover.
3. Use a 10mm socket wrench to remove the four nuts securing the fuel pump cover. Remove the fuel pump cover and lay to the side out of the work area.
4. Grasp the fuel pump electrical connection and slide its locking mechanism out to release it. Disconnect the plug from the pump.
5. Flip the plug over and identify the blue/white wire. This is the 12V power supply to the pump.
6. Follow the wire into the plug and identify the terminal it is connected to. This is where you will check with a multimeter or test light to verify the pump is being supplied with power.
7. You can use either a multimeter or 12V test light when performing a BMW E46 fuel pump test. If you are working by yourself, we suggest using a test light...it is much easier to use than a multimeter if you don’t have a helper.
8. Connect the test light to a suitable ground - we use the door catch as shown below.  Insert the test light into the 12v power terminal fed by the blue/white wire.
9. Turn the key to the second position. The test light should light up for approximately one second.
10. If the test light confirms there is power at the pump, proceed to section 4 to check the fuel line pressure. If the test light shows there isn’t power at the pump, the next step is to check the fuses and the relay.

There are two fuses feeding the fuel pump relay with power; a 15 amp fuse located in the glove box fuse block, and a 20 amp fuse located in the engine compartment E-box. Unless you are experiencing a host of other issues with your vehicle (like the car going into "limp mode"), it is doubtful the 20 amp E-box fuse is blown. But since it only takes a few minutes to check it, we include it in our BMW E46 fuel pump test.

1. Open the hood and use a T30 torx bit to remove the cover off of the E-box.
2. Identify the E-box fuse holder. Use a metal pick to pry the cover open on the fuse holder. Slide the cover back so the fuses can be accessed.
3. The 20 amp fuse in the third position is connected to the fuel pump relay. Inspect it to make sure it is not blown.
4. Reassemble the E-box.
5. Next, move to the glove box. The vehicle's main fuse block is located in the top of the glove box. Turn the two thumb releases on its cover to access the fuses.
6. The fuel pump 15 amp fuse is #54, approximately in the center of the fuse block. Pull the fuse and inspect it to see if it's blown.
7. If you had to replace either of the fuses because they were blown, retest the fuel pump to see if it has power. If it still does not have power at the blue/white terminal, then proceed to section 2 to test the relay.

If neither of the fuel pump fuses are blown, or if you still do not have power at the fuel pump after replacing a blown fuse, then most likely the power issue is due to a faulty relay. The fuel pump relay is located behind the glove box in the control module rack. In order to access it so it can be properly tested, the glove box will need to be removed.

1. In order to access the fuel pump relay, you will need to remove the passenger side glove box. The first step is to detach the door from the side catches by removing the two plastic pins (rivets) with a flat blade screwdriver.
2. Remove the five phillips head screws securing the glove box housing to the dashboard.
3. Disconnect the three wiring connections from the back of the housing.
4. Next, the lower dashboard trim needs to be pulled loose. It is simply held in place with a plastic tab that slides into the plastic module mounting rack. Grab the trim and pull it out, then push it down and out of the way.
5. With the lower dash trim out of the way, you can now access the 8mm nut anchoring the bottom of the module rack to the firewall. Use an 8mm nut driver to remove the nut.
6. The module mounting rack is anchored at the top by two dashboard hooks that it snaps into.
7. To unsnap it from the two dashboard hooks, grasp the top of the mounting rack and push forward (towards firewall).
8. Pull the rack down so the fuel pump relay can be accessed.
9. Locate the fuel pump relay and remove it from its holder by grasping it with your fingers and pulling it straight out.
10. The first step in testing the relay is to verify it is getting power. The relay gets power at two of its four terminals; at terminal 8 from the E-box fuse block, and at terminal 6 from the glove box fuse block.
11. Start by verifying there is power at terminal 8 from the E-box fuse with a test light or multimeter. Use the door hinge bolt as a ground (see image below). You must turn the key to position 2 (“start”) position to test the power at terminal 8. Once you verify there is power, proceed to the next step. If you are not getting power at terminal 8, then you have an issue in the E-box...recheck fuse #3 to make sure it is not blown.
12. Next, you will need to verify there is not an issue between glove box fuse block and the relay. Confirm there is power at terminal 6 from the glove box fuse using a test light or multimeter. You do not have to turn the key to position 2...there is always power at terminal 6 whether the key is turned or not. Once you verify there is power, then proceed to the next step. If you are not getting power at terminal 6, then you have an issue in the glove box fuse block...recheck fuse #54 to make sure it is not blown.
13.  Before proceeding with steps 14 and 15, you will need to make a test wire. Cut approximately six inches of 14 gauge wire and strip the ends. Crimp a 1/4" male "spade" disconnect to each end as shown below. You must have the 1/4" male spade disconnect on each end of the wire to properly insert it into the terminal for testing.
14. Next you will need to verify there is not a DME issue by confirming the fuel pump relay is properly grounded when the ignition key is turned on. The DME “triggers” the pump relay by supplying a ground to terminal 4 when the key is turned. Testing the DME ground is very simple. Start by inserting one end of your test wire into terminal 4 in the relay holder. Next, attach the ground lead of a test light to the the other end of the test wire. Insert the probe of the test light into terminal 8 from the Ebox fuse. Turn the ignition key to position two. If the test light activates, then you have the proper ground being supplied from the DME. If the test light does not activate, there may be an issue with the DME or with its wiring to the fuel pump relay.
15.  Finally, you will need to confirm that there is not an electrical issue between the relay and the fuel pump. This is simply done by “jumping” terminal 6 (glove box fuse #54) to terminal 2 (fuel pump power supply). Insert one end of your test wire into terminal 6 and the other end into terminal 2. Use a test light or multimeter to verify there is power being supplied by the blue/white fuel pump plug wire. If there is power at the pump, then through the process of elimination you have determined that the relay is bad and is the cause of the pump not running. You can order a new relay by clicking here. If there is not power at the pump, then you have an electrical issue between the relay and the fuel pump plug. We suggest thoroughly cleaning the plug with CRC Electronics Cleaner and checking for any broken wires.

If you have identified and repaired an electrical issue with the fuel pump and the vehicle is running normal, then there is no need to continue with this step. If you have power to the fuel pump, but your vehicle is still exhibiting symptoms of a failing fuel pump (difficult to start, engine stalling out, very poor performance) you will need to perform a fuel line pressure test. Performing a pressure test on the fuel system requires attaching a fuel pressure gauge (available from any auto parts store or our tool list above) to the fuel rail at the top of the engine. Fortunately, BMW made it very easy to access and test the fuel rail on the E46 3 series...it can be done in about 15 minutes. To perform a fuel line pressure test, please read our article BMW Fuel Pressure Test – Fuel Rail/Schrader Valve Method.