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Fuel Pump Replacement
 
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Pelican Technical Article:

Fuel Pump Replacement

Nick Czerula

Time:

3 hours3 hrs

Tab:

$300

Talent:

*****

Tools:

Socket set, fuel pump collar tool, brass punch, rubber mallet

Applicable Models:

BMW Z4 Coupe/Conv (2006-08)

Parts Required:

Fuel pump, fuel pump sealing O-ring

Hot Tip:

Clean top of fuel tank before removing pump

Performance Gain:

Repair faulty fuel pump

Complementary Modification:

Replace fuel filter

The fuel supply system in a BMW Z4(M) consists of:

  • Fuel tank.
  • Fuel filler with associated breathing and venting pipes.
  • High pressure fuel pump assembly with fuel filter and fuel level senders.

The fuel tank is two-lobed. There is one fuel level sender, located in the right side of the tank mounted to the bottom of tank. The right fuel tank lobe holds the fuel level sender, fuel filter and the fuel pump.

In tank fuel pumps have many benefits, the fuel is submerged in fuel keeping it cool, preventing vapor lock and electrical issues. The fuel pump delivers a constant flow of gasoline to the fuel rail at a regulated pressure and volume. The fuel pump draws fuel from the fuel tank and pushes it through the fuel filter, mounted outside of the fuel tank.

A faulty fuel pump can cause poor engine performance and hard starting problems. When it fails completely, you may be left with an engine that doesn't start. If you suspect your fuel pump has failed, you can confirm the fuel pump has received the correct voltage when commanded ON by the fuel pump relay using a digital volt ohm-meter (DVOM). If the correct voltage is present, but the pump does not activate, it is likely faulty. Use the DVOM in conjunction with a wiring diagram to determine the correct terminals for testing. You can access terminals in the trunk behind the battery. See our tech article on fuel pump testing.

Replacing the fuel pump on a Z4 can be done without removing the fuel tank. There is an access panel under the right side of the vehicle that allows servicing. It is best to replace your fuel pump with the fuel tank drained. Otherwise the fuel in the tank will spill when it is removed. When replacing, work in a well-ventilated area. Working outdoors is a good choice. Do not use incandescent work lights or power tools. Fuel and fuel vapors are highly combustible.

To relieve fuel pressure, remove the fuel pump relay and crank the engine until engine starts and stall. See our tech article on fuel pump testing.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Drain your fuel tank. Run the vehicle for about 20 seconds. This equalizes the amount of fuel in the siphon unit.

Disconnect the negative battery cable. See our tech article on battery replacing and reconnecting notes.

Remove the fuel cap, then slide an anti-static siphon hose down the fuel filler neck. Once the hose has bottomed out, pump fuel out of the fuel tank into a suitable storage container. If you are unsure of the amount of fuel in your tank, you can monitor the fuel level via the fuel level sender units. As the fuel level drops, the fuel level sender resistance drops. You can measure this across the terminals at both sender units with a digital volt / ohm meter (DVOM). You will need a wiring diagram from a repair manual.

The fuel pump, filter and sending unit is located in the right (red arrow) side of the fuel tank.
Figure 1

The fuel pump, filter and sending unit is located in the right (red arrow) side of the fuel tank. Remove the entire exhaust system. See our tech article on exhaust system replacing.

With the exhaust removed, remove the two 10mm nuts (red arrows) on the heat shield to the right of the transmission mount bracket (purple arrow).
Figure 2

With the exhaust removed, remove the two 10mm nuts (red arrows) on the heat shield to the right of the transmission mount bracket (purple arrow).

Working at the rear of the exhaust heat shield (red arrow), remove the two 8mm mounting fasteners (purple arrows).
Figure 3

Working at the rear of the exhaust heat shield (red arrow), remove the two 8mm mounting fasteners (purple arrows).

Next, remove the 10mm nut (red arrow) on the heat shield to the Left of the transmission mount bracket.
Figure 4

Next, remove the 10mm nut (red arrow) on the heat shield to the Left of the transmission mount bracket.

Working on the left side of the body, remove the two 10mm nuts (red arrows) on the heat shield.
Figure 5

Working on the left side of the body, remove the two 10mm nuts (red arrows) on the heat shield. Then remove the 8mm fastener (purple arrow), remove this fastener on the right side as well. Support the heat shield as you remove the final fastener.

Remove the exhaust heat shield toward the rear of the vehicle (red arrow).
Figure 6

Remove the exhaust heat shield toward the rear of the vehicle (red arrow). Store it in a safe place, do not bend it when removing. Then remove the driveshaft flex-disc. See our tech article on driveshaft flex-disc replacing. Remove the fuel filter, see our tech article on fuel filter replacing.

Once you have removed the fuel filter, you will be working inside the tank.
Figure 7

Once you have removed the fuel filter, you will be working inside the tank. Be sure you have enough to room to work with both hands and reach inside the fuel tank. It is important the tank is empty for this procedure to prevent fuel spill and contact with your skin. Working inside the fuel tank, feel your way to the front of the fuel pump unit, locate the small plastic catch. Shown here with the fuel pump unit removed (red arrow). You will have to reach inside the tank and locate this catch, release it toward the fuel pump while lifting the pump unit up. Once the catch is released, the rear of the pump slides up and off a bracket, the bracket is inserted into the rear of the pump unit. See next step.

Pull the siphon hose (blue arrow) straight out of the fuel pump unit.
Figure 8

Pull the siphon hose (blue arrow) straight out of the fuel pump unit. DO not bend or kink this line. Not the hole it goes into for installing. This photo shows where the catch will be. Working inside the fuel tank, feel your way to the front of the fuel pump unit, locate the small plastic catch. Shown here with the fuel pump unit removed (red arrow). You will have to reach inside the tank and locate this catch, release it toward the fuel pump while lifting the pump unit up. Once the catch is released, the rear of the pump slides up and off a bracket, the bracket is inserted into the rear of the pump unit.

Next, separate the electrical connector by opening the plastic tabs (red arrows) and pulling it apart.
Figure 9

Next, separate the electrical connector by opening the plastic tabs (red arrows) and pulling it apart.

Then press and hold the green button (red arrow) while pulling the fuel lines apart (blue arrow).
Figure 10

Then press and hold the green button (red arrow) while pulling the fuel lines apart (blue arrow).

Slide the fuel pump unit out of the tank bottom first (red arrow).
Figure 11

Slide the fuel pump unit out of the tank bottom first (red arrow). Be sure the level sender is still in the tank as you slide it out.

Slowly guide the fuel pump with the sender (red arrow) out of the fuel tank, once out, lower the bottom of pump unit to an angle to get sender out.
Figure 12

Slowly guide the fuel pump with the sender (red arrow) out of the fuel tank, once out, lower the bottom of pump unit to an angle to get sender out.

You will be replacing the entire unit (red arrow) as the parts are not serviceable separately.
Figure 13

You will be replacing the entire unit (red arrow) as the parts are not serviceable separately. When installing, replace the fuel pump assembly sealing O-ring. Be sure that the O-ring is properly installed in the fuel tank before installing the fuel pump. Insert the new pump into the tank in reverse steps of removal. Lift the pump up once inside the tank and align the slot (blue arrow) on the pump with the mount in the tank. Once aligned, press the fuel pump down until catch located at front engages. Reconnect the electrical connector and fuel line, then install the siphon hose, be sure it is seated corrected on the holder. Then install the fuel filter. Hand tighten the threaded collar. Then use the BMW special tool 16 1 022 to tighten the threaded collar. Or tap the threaded collar tight (clockwise) with a brass punch and a rubber mallet. Connect the electrical connector. Fill the fuel tank with about two gallons of fuel before attempting to start the vehicle. Once you are sure that the fuel pump is operating normally, fill the remainder of the fuel tank and check for leaks. Once done, reassemble the exhaust.

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Page last updated: Wed 12/7/2016 03:06:16 AM