BMW Cars 1999-06

Fuel Pump

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Removal & Installation




NOTE
If the fuel pump is to be replaced, the fuel filter should also be replaced.


WARNING
Never operate the fuel pump for a prolonged length of time while dry or with a restricted pick up as the pump is cooled and lubricated by the fuel.


NOTE
Follow all precautions when working with gasoline and the resulting gasoline vapors. Relieve the fuel pressure before performing any work on the fuel system.


CAUTION
This procedure will generate gasoline fumes. Absolutely no flame or sparks should be in the area of the work being done. Gasoline fumes are heavier than air and will travel on the floor towards possible sources of ignition. Work in a well-ventilated area and wipe up any gasoline spills. Gasoline will irritate skin; avoid contact with gasoline. Failure to follow these precautions may result in personal injury.

The fuel pump is mounted through the top of the fuel tank along with the fuel level sending unit. The fuel tank should not be filled more than 1 / 3 of the total fuel tank capacity to prevent fuel leakage during fuel pump removal. If the fuel tank is filled beyond this level, the fuel level must be reduced using an approved fuel removal device.

  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Relive the fuel system pressure and disconnect the negative battery cable.
  4.  
  5. Drain the fuel, if filled beyond13
  6.  


NOTE
The fuel pump must be removed through the top of the fuel tank, thus the location of the fuel tank determines whether the fuel pump is accessed by removal of the rear seat, or removal of the trim panels in the trunk.

  1. Remove or disconnect the following:

    Rear seat, or the trim panels in the trunk, depending on fuel tank location to access the top of the fuel tank
     

  2.  


NOTE
On models which require removal of the rear seat, the insulation mat under the seat must be cut in a -U- shape to allow the insulation to be folded up to access the top of the fuel tank.



Fasteners securing the metal cover located above the fuel tank, and remove the cover
 
Electrical connector at the top of the combination fuel pump and fuel level sending unit assembly
 
Fuel feed and return lines
 

  1. Match mark the combination fuel pump and fuel level sending unit assembly to the fuel tank to ensure proper installation during reassembly.

    Fasteners or fastener securing the combination fuel pump and fuel level sending unit assembly to the fuel tank. The fasteners are one of 2 types.
     

  2.  
  3. If the fuel pump assembly is fastened to the fuel tank with a series of 6 mm nuts:
    1. Loosen the nuts evenly using a crisscross sequence and carefully lift the cover and place aside.
    2.  
    3. Compress the large plastic tongue to release the fuel pump, and lift the pump along with the fuel sending unit out of the fuel tank.
    4.  

  4.  
  5. If the fuel pump assembly is fastened to the fuel tank with a large sealing ring:
    1. Use tool No. 16-1-020 to loosen the sealing ring in a counterclockwise direction.
    2.  
    3. With the seal ring removed, lift the fuel pump assembly out of the fuel tank.To install:
    4.  

  6.  


NOTE
Always use a new seal or gasket when installing the fuel pump or fuel level gauge sending unit assembly.

  1. Install the fuel pump into the fuel tank taking care not to bend or damage the fuel sending unit assembly.
  2.  
  3. If the fuel pump is held in place by a plastic bracket in the fuel tank perform the following:
    1. Make sure the fuel pump is fully snapped in place.
    2.  
    3. Install the fuel tank cover plate with a new gasket and torque the fasteners using a crisscross pattern to 57 inch lbs. (6.5 Nm).
    4.  

  4.  
  5. If the fuel pump is held in place with a sealing ring perform the following:
    1. Ensure the pump is properly aligned with the fuel tank matchmarks made during disassembly.
    2.  
    3. Install a new seal and torque the sealing ring using tool No. 16-1-020 as follows:
    4.  



    Metal sealing rings: 26 ft. lbs. (35 Nm)
     
    Plastic sealing rings: 41 ft. lbs. (55 Nm)
     

  6.  
  7. The balance of the assembly is in reverse order of disassembly.
  8.  
  9. Connect the negative battery cable.
  10.  
  11. Once the vehicle is started, check for leaks. If a strong fuel odor is present, or any fuel leakage is noted, stop the engine immediately and repair as necessary.
  12.  

The fuel pump is mounted through the top of the fuel tank along with the fuel level sending unit. The fuel tank should not be filled more than 1 / 3 of the total fuel tank capacity to prevent fuel leakage during fuel pump removal. If the fuel tank is filled beyond this level, the fuel level must be reduced using an approved fuel removal device.

  1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
  2.  
  3. Remove or disconnect the following:
    NOTE
    The fuel pump must be removed through the top of the fuel tank, thus the location of the fuel tank determines whether the fuel pump is accessed by removal of the rear seat, or removal of the trim panels in the trunk.


    NOTE
    On models which require removal of the rear seat, the insulation mat under the seat must be cut in a -U- shape to allow the insulation to be folded up to access the top of the fuel tank.



    Residual fuel system pressure
     
    Negative battery cable
     
    Fuel, if filled beyond 1 / 3 of the capacity of the fuel tank. Drain the fuel tank enough to prevent spillage when removing the pump using an approved fuel removal device.
     



    Rear seat, or the trim panels in the trunk, depending on fuel tank location to access the top of the fuel tank
     



    Fasteners securing the metal cover located above the fuel tank, and remove the cover
     
    Electrical connector at the top of the combination fuel pump and fuel level sending unit assembly
     
    Fuel feed and return lines
     

  4.  
  5. Match mark the combination fuel pump and fuel level sending unit assembly to the fuel tank to ensure proper installation during reassembly.
  6.  
  7. Remove the fasteners or fastener securing the combination fuel pump and fuel level sending unit assembly to the fuel tank. The fasteners are one of 2 types.
  8.  
  9. If the fuel pump assembly is fastened to the fuel tank with a series of 6 mm nuts:
    1. Loosen the nuts evenly using a crisscross sequence and carefully lift the cover and place aside.
    2.  
    3. Compress the large plastic tongue to release the fuel pump, and lift the pump along with the fuel sending unit out of the fuel tank.
    4.  

  10.  
  11. If the fuel pump assembly is fastened to the fuel tank with a large sealing ring:
    1. Use tool No. 16-1-020 to loosen the sealing ring in a counterclockwise direction.
    2.  
    3. With the seal ring removed, lift the fuel pump assembly out of the fuel tank. To install:
      NOTE
      Always use a new seal or gasket when installing the fuel pump or fuel level gauge sending unit assembly.

    4.  

  12.  
  13. Install the fuel pump into the fuel tank taking care not to bend or damage the fuel sending unit assembly.
  14.  
  15. If the fuel pump is held in place by a plastic bracket in the fuel tank perform the following:
    1. Make sure the fuel pump is fully snapped in place.
    2.  
    3. Install the fuel tank cover plate with a new gasket and torque the fasteners using a crisscross pattern to 57 inch lbs. (6.5 Nm).
    4.  

  16.  
  17. If the fuel pump is held in place with a sealing ring perform the following:
    1. Ensure the pump is properly aligned with the fuel tank matchmarks made during disassembly.
    2.  
    3. Install a new seal and torque the sealing ring using tool No. 16-1-020 as follows:

      Metal sealing rings: 26 ft. lbs. (35 Nm)
       
      Plastic sealing rings: 41 ft. lbs. (55 Nm)
       

    4.  

  18.  
  19. The balance of the assembly is in reverse order of disassembly.
  20.  
  21. Connect the negative battery cable.
  22.  
  23. Once the vehicle is started, check for leaks. If a strong fuel odor is present, or any fuel leakage is noted, stop the engine immediately and repair as necessary.
  24.  

The fuel pump is an electrical unit, delivering fuel through a pressure regulator, to a fuel distributor or a ring-line for the injection valves. The fuel pump is mounted under the vehicle, in the fuel tank, or in the engine compartment.

  1. Relieve fuel system pressure. Disconnect the negative battery connector. Push back any protective caps and disconnect the electrical connector(s).
  2.  
  3. If the fuel lines are flexible, pinch them closed with an appropriate tool. Disconnect the fuel lines and plug the ends.
  4.  
  5. Remove the retaining bolts and remove the pump and expansion tank as an assembly.
  6.  
  7. The pump can be separated from the expansion tank after removal.
  8.  

To install:

  1. Install the pump in the correct position, be sure to use similar types of hose clamps, if any need replacing. The wrong type clamp can damage the pressure lines.
  2.  
  3. Run the engine and check the fuel lines for leakage. Check the fuel system pressure.
  4.  

The fuel pump is mounted through the top of the fuel tank along with the fuel level sending unit. The fuel tank should not be filled more than 1 / 3 of the total fuel tank capacity to prevent fuel leakage during fuel pump removal. If the fuel tank is filled beyond this level, the fuel level must be reduced using an approved fuel removal device.

  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Relive the fuel system pressure and disconnect the negative battery cable.
  4.  
  5. Drain the fuel, if filled beyond 1 / 3 of the capacity of the fuel tank. Drain the fuel tank enough to prevent spillage when removing the pump using an approved fuel removal device.
    NOTE
    The fuel pump must be removed through the top of the fuel tank, thus the location of the fuel tank determines whether the fuel pump is accessed by removal of the rear seat, or removal of the trim panels in the trunk.

  6.  
  7. Remove or disconnect the following:
    NOTE
    On models which require removal of the rear seat, the insulation mat under the seat must be cut in a -U- shape to allow the insulation to be folded up to access the top of the fuel tank.



    Rear seat, or the trim panels in the trunk, depending on fuel tank location to access the top of the fuel tank
     



    Fasteners securing the metal cover located above the fuel tank, and remove the cover
     
    Electrical connector at the top of the combination fuel pump and fuel level sending unit assembly
     
    Fuel feed and return lines
     

  8.  
  9. Match mark the combination fuel pump and fuel level sending unit assembly to the fuel tank to ensure proper installation during reassembly.

    Fasteners or fastener securing the combination fuel pump and fuel level sending unit assembly to the fuel tank. The fasteners are one of 2 types.
     

  10.  
  11. If the fuel pump assembly is fastened to the fuel tank with a series of 6 mm nuts:
    1. Loosen the nuts evenly using a crisscross sequence and carefully lift the cover and place aside.
    2.  
    3. Compress the large plastic tongue to release the fuel pump, and lift the pump along with the fuel sending unit out of the fuel tank.
    4.  

  12.  
  13. If the fuel pump assembly is fastened to the fuel tank with a large sealing ring:
    1. Use tool No. 16-1-020 to loosen the sealing ring in a counterclockwise direction.
    2.  
    3. With the seal ring removed, lift the fuel pump assembly out of the fuel tank. To install:
      NOTE
      Always use a new seal or gasket when installing the fuel pump or fuel level gauge sending unit assembly.

    4.  

  14.  
  15. Install the fuel pump into the fuel tank taking care not to bend or damage the fuel sending unit assembly.
  16.  
  17. If the fuel pump is held in place by a plastic bracket in the fuel tank perform the following:
    1. Make sure the fuel pump is fully snapped in place.
    2.  
    3. Install the fuel tank cover plate with a new gasket and torque the fasteners using a crisscross pattern to 57 inch lbs. (6.5 Nm).
    4.  

  18.  
  19. If the fuel pump is held in place with a sealing ring perform the following:
    1. Ensure the pump is properly aligned with the fuel tank matchmarks made during disassembly.
    2.  
    3. Install a new seal and torque the sealing ring using tool No. 16-1-020 as follows:

      Metal sealing rings: 26 ft. lbs. (35 Nm)
       
      Plastic sealing rings: 41 ft. lbs. (55 Nm)
       

    4.  

  20.  
  21. The balance of the assembly is in reverse order of disassembly.
  22.  
  23. Connect the negative battery cable.
  24.  
  25. Once the vehicle is started, check for leaks. If a strong fuel odor is present, or any fuel leakage is noted, stop the engine immediately and repair as necessary.
  26.  

E30 Models
Except M3 With External Pump


Click image to see an enlarged view

Fig. The fuel pump is located in the fuel tank and is accessible once the rear seat cushion is removed

The M3 models with the S14 engine are equipped with two fuel pumps. The main pump is located outside the fuel tank and a pre-pump or transfer pump mounted in the fuel tank. Use the following procedures to remove the in-tank pre-pump on M3 S14 models and all other E30 models.

  1. Disconnect the negative battery cable.
  2.  
  3. If the tank is full, remove some fuel to lower the level.
  4.  
  5. Remove the rear seat cushion and peel back the insulating sheet to access the right side cover.
  6.  
  7. Remove the screws from the cover and lift the cover off. Pull off the electrical plug and disconnect the fuel lines. Catch any spilled fuel.
  8.  
  9. Remove the four screws from the sender portion of pickup assembly. Slowly remove the sender to allow the fuel to drain into the tank.
  10.  
  11. Rotate the pickup assembly counterclockwise and pull out slowly. Allow the fuel to drain back into the tank.
  12.  

To install:

  1. Replace the gasket and lower the pickup assembly into the fuel tank. Rotate the assembly clockwise to lock into place.
  2.  
  3. Replace the gasket and lower the fuel level sender into the pickup assembly. Replace the screws.
  4.  
  5. Connect the fuel lines and electrical connector. Replace the cover and the insulating sheet. Install the rear seat cushion.
  6.  
  7. Connect the negative battery cable and check for normal operation and fuel leaks and repair as necessary.
  8.  

M3 With External Pump

The M3 is equipped with two fuel pumps. The main pump is located outside the fuel tank and a pre-pump or transfer pump mounted in the fuel tank. To replace the main pump, proceed as follows:

  1. Disconnect the negative battery cable.
  2.  
  3. Make sure the ignition switch is in the OFF position.
  4.  
  5. Use fuel line block-off clamps on the inlet and outlet lines of the fuel pump to prevent fuel from leaking out once the fuel pump has been removed.
  6.  
  7. Pull back the electrical connection covers and remove the wires. Loosen the hose connections and remove the hoses.
  8.  
  9. Remove the nuts holding the fuel pump and remove the assembly. Disconnect the hose from the pump and remove the pump from the bracket.
  10.  



Click image to see an enlarged view

Fig. The fuel supply system-E30 Series M3 shown

To install:

  1. Install the pump in the bracket and connect the hose. Install the pump and bracket onto the car. Replace the rubber isolators if necessary.
  2.  
  3. Connect the hoses and the electrical connections. Remove the block off clamps.
  4.  
  5. Attach the fuel lines and electrical connector. Replace the cover and the insulating sheet. Install the rear seat cushion.
  6.  
  7. Connect the negative battery cable and check for normal operation and fuel leaks and repair as necessary.
  8.  

E36 Models

The fuel pump is located in the fuel tank and attached to the fuel level sensor assembly. Refer to the fuel level sensor removal procedures in Section 2 for removal and installation details.


NOTE
On models with two fuel level sensors, the fuel pump is installed with the right side sensor.



Click image to see an enlarged view

Fig. View of the fuel pump and level sender assembly-E36 models



Click image to see an enlarged view

Fig. The fuel pump is located in the fuel tank and attached to the fuel level sensor-E36 model shown

Testing



Electrical Diagnosis


Click image to see an enlarged view

Fig. View of the fuse and relay box containing the fuel pump relay and related components

When the ignition switch is first turned to START , the control unit will complete the ground circuit for the pump relay coil and the relay closes to run the pump. When the control unit receives a signal from the crankshaft pulse sensor, it will continue to operate the pump relay with the ignition switch in the RUN position. If the engine is not rotating, the pump will not operated. For troubleshooting purposes, the fuel pump relay terminals can be jumped to test the pump's electrical circuit and to run the pump for fuel system pressure testing.

  1. If a fuel supply problem is suspected, remove the pump relay and check for 12 volts at terminal 30 of the relay socket. With the ignition switch ON , there should be 12 volts at terminal 86 from the main DME relay.
  2.  
  3. Jump terminals 30 and 87 with a fused jumper on the relay socket. There should be power to the pump's fuse and to the pump. Measure the voltage at the battery, then measure the voltage at the fuel pump. If the fuel pump voltage is 0.3 volts less than the battery voltage, check the fuel pump wiring for damage or a poor connection and repair as necessary.
  4.  
  5. Use a fused jumper wire to supply 12 volts to terminal 86 and ground to terminal 85 on the relay itself. Do not reverse the polarity or the relay will be destroyed. The relay should close and there should be continuity between terminals 30 and 87.
  6.  
  7. If the pump runs when the terminals are jumped and the relay is good, but the pump stops when the ignition switch is in the RUN position, the control unit may not be receiving a signal from the crankshaft pulse sensor.
  8.  
  9. The pump can also be checked for a current draw by connecting an ammeter in series to the positive lead of the fuel pump. The current draw on the fuel pump should not exceed 5.0 amps. If the current draw is excessive, check for a restricted fuel pick up screen, fuel line or fuel filter and replace or repair as necessary. If the current draw remains above 5.0 amps, the pump should be replaced.
  10.  

Fuel Delivery And Pressure Testing

NOTE
On vehicles with metal fuel lines, if a fuel rail adapter is not available, check the fuel pump pressure at the fuel pump outlet. On vehicles with in tank fuel pumps, access the outlet fuel line located at the top of the fuel gauge sending unit.


CAUTION
The following procedure will produce fuel vapors. Make sure there is proper ventilation and take the appropriate fire safety precautions otherwise personal injury may occur.

  1. Make sure the battery is in good condition and the fuel pump wiring and ground connections are good. It is important the pump receive a full 12 volts.
  2.  
  3. Disconnect the fuel supply hose. Install a 13 3 60 or an equivalent 100 psi pressure gauge with a T-fitting.
  4.  
  5. Disconnect the fuel return hose and securely install a long hose to the return fitting. Place the other end into a 4 quart or 4000 cc measuring container.
  6.  
  7. Remove the fuel pump relay and connect a jumper wire with a switch to relay socket terminals 30 and 87. The pump will run whenever the terminals are connected, so be sure to use a jumper with a switch.
  8.  
  9. Run the pump for 30 seconds and time the run carefully. The pump should flow as follows:

    4-cylinder engines: 29.6 oz. (875 cc) in 30 seconds
     
    6-cylinder engines except Z3 and M50/S50: 29.6 oz. (875 cc) in 30 seconds
     
    M50 and S50 engines: 37.8 oz. (1120 cc) in 30 seconds
     
    6-cylinder Z3 engines: 34.8 oz. (1030 cc) in 30 seconds
     

  10.  
  11. If the flow is low, the pump is faulty or the filter is clogged.
  12.  
  13. Connect the fuel return hose and operate the pump carefully. The pump's operating pressure should be as follows:

    4-cylinder engines: 42.6-44.4 psi (2.94-3.06 bar)
     
    6-cylinder engines: except Z3 and M50/S50 engines: 42.6-44.4 psi (2.94-3.06 bar)
     
    Z3 and M50 & S50 6-cylinder engines: 49.9-51.6 psi (3.44-3.56 bar)
     

  14.  
  15. If the flow is correct but the pressure is low or does not hold, clamp the return hose and run the pump again briefly to read the pressure. If the pressure is now correct and holds, the pressure regulator in the supply rail is faulty.
  16.  
  17. If the pressure is still low or does not hold, there is a leak in the system, possibly an injector or the fuel pump check valve. The pressure will be lower if the engine is running because the pressure regulator will be supplied with engine vacuum.
  18.  
  19. If the fuel pressure appears to be low, repeat the pressure test while gradually pinching off the fuel return line. If the pressure does not rise quickly and remains low, replace the pump assembly.
  20.  
  21. If the fuel pressure is too high and the fuel lines and filter are good the fuel pump check valve may be stuck closed and should be replaced.
  22.  
  23. When the pump is stopped, the pressure should not drop more than 7 psi (.5 bar) for 20 minutes. If the pressure does not hold, there is a leak within the system, possibly an injector, fuel pressure regulator or the fuel pump check valve. The symptoms of this condition of each of these could be:
  24.  

Injector:



Engine misfire, or rough idle
 
Reduced fuel economy
 

Fuel pressure regulator:



Poor off idle response, hesitation or poor acceleration
 

Fuel pump check valve:



Hard starting with warm engine
 
Temporary rough idle during warm engine restart
 

Pressure Testing
  1. Relieve fuel system pressure. Tee a pressure gauge into the fuel feed line in front of the pressure regulator. Plug the fuel return hose.
  2.  
  3. Pull off the pump relay. Jumper terminals 87 and 30 . Measure the delivery pressure. It should be 43 psi on vehicles except the 7 Series. On these vehicles, it should be 48 psi.
  4.  

 
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