Fuel Tank

[Jasonr816]

I am working on a 2004 Z4 3.0 auto. I am replacing the fuel pump. My question is there are two plugs in the tank one is blue for the pump the other is yellow . What is the yellow plug go to and is the part serviceable if the wires are damaged?

[patriot66]

Hi Jason. Do you mean these ?

20220209_142948.jpg (119.12 KiB) Viewed 721 times

20220209_143529.jpg (98.6 KiB) Viewed 721 times

I would imagine it is for the fuel level sensor as there is nothing else in there

[enuff_zed]

Random and possibly completely wrong thought but........
All the other yellow plugs in the car seem to be for safety stuff, airbags etc.
Could the yellow one be some kind of pump cut out in the event of an accident?

[patriot66]

Random and possibly completely wrong thought but........
All the other yellow plugs in the car seem to be for safety stuff, airbags etc.
Could the yellow one be some kind of pump cut out in the event of an accident?

Maybe. All the wires from the blue/yellow plugs go to the pump/level sender. The relevant diagram on www.realoem.com shows 1 plug with 4 wires, 2 going to the pump and 2 to the level sensor

Screenshot_20221212-145432_Chrome.jpg (88.79 KiB) Viewed 680 times

However, in my photos the red and black wires appear to go to the pump and 4 brown wires to the level sensor ?

[Jasonr816]

Thank you for your response . In the photo the yellow plug seperates from the blue plug . the blue plug goes to the fuel pump assembly I am not sure what the yellow plug is for ? The wires on the yellow plug run over to the driver side of the tank and plug into something inside the tank. The wire insulation has come off the wires on the yellow plug and I am unsure if the other end of the plug is accessible for repair or I need to buy a new tank.

[Z4Mariner]

Watching to learn from your thread. Although my coupe is LHD, I doubt BMW designed two separate fuel tank systems. I haven't found a free TIS, and my Bentley manuals cover E46 and E90-E93 only - so learning from other Z4 owners is extremely helpful !

[Jasonr816]

Does anyone know the procedure for removing the gas tank . The tank does not appear to clear the rear diff or rear trailing arms . Any help would be great.

[patriot66]

Does anyone know the procedure for removing the gas tank . The tank does not appear to clear the rear diff or rear trailing arms . Any help would be great.

Looking at my own photos from when I replaced the fuel filter/pressure regulator and others on the Internet I think you'll struggle to drop the fuel tank without first removing most of/all the rear subframe and suspension, prop-shaft, hand brake cables, heat shields etc

[Liam22]

Does anyone know the procedure for removing the gas tank . The tank does not appear to clear the rear diff or rear trailing arms . Any help would be great.

Exhaust, heat shields, propshaft need to be removed. Disconnect the handbrake cables. The rear tie rods and "dogbone" bracket need to be removed but the subframe and rear suspension can stay put. The tricky part is the filler neck. It's permanently attached to the tank which makes the whole thing difficult to remove (and more difficult to reinstall). I *think* the lower trailing arm needed to be detached to clear the filler neck, but not completely removed.

[Jasonr816]

Liam you are correct I removed the rear suspension cradle from the car that allowed the fuel tank to drop out of the car I am replacing the tank due to the wiring harness inside the tank being burned up and not repairable. Thank you for the help on this issue.

[Gil Jackson]

Jason,
I never saw a response to the bare wire condition, nor what the yellow plug wiring goes to. I have mine disassembled now, and have the exact same bare wire findings. Could you tell me how you resolved the issue? Thank you.

Edit - Patriott66 above has a picture of the SIX wires that are connected to the fuel side of the Filter / Regulator, but it's only four wires that go from the blue connector that go to the fuel pump/Level Sensor. I have that out anon my work bench. As the Blue/Yelow connectors will separate, still in the tank is the yellow connector with the last two of the six wires running off into the tank. Still looking for an answer of what those might do, and if the car can be reassembled with that connector disabled. If they were both brown, as with the level sensor, they may remeasuring a resistance only, so seeking variation on 12 volts. If disconnected, or shorted together external to the tank, what system would that affect?

Thanks again.