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E60 / E61 (2004 - 2010)
BMW 5-Series E60 Sedan was first seen in the Unites States in the fall of 2003 with a 2004 Model Year designation. The E61 wagon followed shortly there after. The E60/E61 5 series is now available as a 528i, 528xi, 535i, 535xi, 550i and a 535xi sports wagon! -- View the E60 Wiki

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Old Today, 08:42 AM
drwisniewski drwisniewski is offline
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Location: Bay City, MI USA
Join Date: Jan 2014
Posts: 18
Mein Auto: 2004 525i
Fuel Pump Relay Issue

I have been having intermittent issues with very momentary stalls. These are more than just an engine "cough", it cuts out totally and then recovers in an instant causing strong jolting hesitation when driving. If it experiences 2 or 3 of these intermittent stalls in quick succession, then the engine can't recover and will completely stall. Very distinctly with each intermittent stall, I can hear the fuel pump relay behind the glove box clicking. I have swapped and replaced the relay and the issue continues.

Also, I cannot identify any consistent circumstances which causes this to happen. Many times the vehicle runs fine. It has occurred in rainy/wet conditions as well as dry. Hot or cold. Fresh start and after 15 minutes of running (at running temp). Full tank or 1/4 tank of gas.

I have not been able to find out what controls the fuel pump relay in the glove box. What is signalling it to open and close? Is there a pressure sensor on the fuel pump itself that tells the relay to open? I'm thinking my next step will be to replace the fuel pump itself assuming that it may be what is sending the instruction to the relay to cut it's power, but I don't know that for sure.

Thanks for any advice!

2004 E60 525i

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Old Today, 09:42 AM
toga94m toga94m is offline
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Location: Upstate NY
Join Date: Apr 2012
Posts: 633
Mein Auto: 2006 530xiT
I'm guessing your 2004 525i has the letters "NA53" in the VIN, and this diagram applies -
Which leads me to see your DME (engine control) is an MS45.

Wiring diagrams are here http://www.bmw-planet.net/diagrams/r...0e61/index.htm though you'll have to use Internet Explorer since Chrome and Firefox don't support Java anymore.

I'm attaching a screenshot showing the smarts around the fuel pump and relay. There are a lot of things fed from Fuse F02, so I doubt that's the reason the relay clicks.

Do you have an OBDII code reader that could give you better diagnostic info? Any check-engine light during the events? Does the tachometer drop to zero during these events, or does keep tracking engine speed? There are zillions of things going thru the DME's mind at any given instant, and any of them could make it want to shut off the fuel pump.

From that same page -
Fuel pump relay
The control unit can only monitor activation of the relay but not of the pump itself. A safety circuit ensures the relay can only be activated with the engine running and only shortly after switching the ignition lock to position 2 in order to build up pressure.
Once the engine shuts down, the DME control unit no longer recognized engine speed and immediately switches off the relay. This ensures that the fuel pump cannot continue running when the engine turned off.
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2006 530xiT 6MT - 143k miles - 3rd owner - sport & cold packages
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