It seems like the fuel pump on my ‘05 R53 is always making noise when the key is in the run position.

Is this priming? Or normal operation?

Tech told me he thinks the fuse panel needs to be replaced since the fuel pump relay is mounted to back of it on 2005.

I found a little info about this online but my relay seems to be stuck on? Usually relay fails and car won’t start.

Looking for some advice and willing to swap fuse panel if that’ll solve it.

Thx!

 

When you turn the key to the "ON" (second from key insertion) position, it's supposed to spool up for 2-3 seconds and stop.

Maybe try swapping the relay out for a known good one for the next step.

Not sure how a fuse panel replacement would help this issue.

 

When the key is turned to the "ON" position, the pump spools up and keeps spooling and doesn't stop. I'm assuming this is supposed to just prime for a few seconds?

This link shows that for later year R53's the fuel pump relay is permanently soldered to the back side of the interior fuse box circuit boards. https://gethypoxic.com/blogs/technic...ertible-mcs-06

But his relay had failed Off. I don't know if mine has failed On, or if I need to replace something else to prevent the fuel pump from continually spooling?

 

On RealOEM, it looks like fuse box part# 61136906600 was used until 09/05 and part# 61146906626 was used from 09-05 onward.

I can't tell for sure, but something might have changed on those two parts relating to the fuel pump relay.

I have a 2005. I need to check my build date.

 

Those are the same number but yeah something changed because what's in my foot well fuse panel looks nothing like what the Bentley manual has. Looks like they reformed the panel so now the bottom three or four relay positions are blanked off, and the relays are now behind the fuse panel and ostensibly soldered in well out of your reach, so naturally you're expected to go to the Stealership to replace one, because BMW is Satan.

 

Sorry, I fixed the part #'s in the above post.

I checked my VIN and build is 02/2005.

 

So it looks like mostly 2006's would have the newer few box.

I'll check mine to see if I have the original version. It looks like the fuel pump relay might be a plug in style.

But I still don't know if that's the problem. Seems like they mostly fail and don't work at all, not get stuck On.

 

Just found this in case it helps. Shows the differences between the earlier 2002-2005 and later 2005-2008 fuse box layouts. Note the "not serviced" designation for the fuel pump in the latter. Also no indication of the 2005 month of production transition.

Also, used 2005-2008 model on WayMotorWorks for $200:
https://www.waymotorworks.com/used-r...-fuse-box.html


Finally, an eBay listing for another used one, this one has a picture of the reverse side and attached (?) relays

https://www.ebay.com/itm/16576071325...gAAOSwvM1jMy4G

 

So, I have the older fuse box since my car has build month of 02/2005.

I'm looking at these schematic and relay images and can't figure out what makes the fuel pump prime versus just run regularly. Anyone know what all the symbols mean?


generic part# for fuel pump relay

schematic on the relay

This might be for a 2006 newer fuse box design, so might not apply for my car.

 

Edited because I realized I misunderstood your question.

Not sure the answer to it, but I do envy your ability to Easter egg the relay and see if it solves the issue.

This is the schematic from Bentley corresponding to your build date:

 

Maybe my fuel pump relay is OK. The car runs and drives. It just sounds like the fuel pump is priming / buzzing all the time. Even with engine off, and key in run position, the fuel pump doesn't shut off after a few seconds like it used to.

There's the "Hot in On or Start" wire in the schematic above but it doesn't really go thru the relay rectangle.

I can't tell what ends the priming mode of the fuel pump (if there is such a thing as priming mode). Is there a pressure switch or anything like that?

 

That was a great video about relays. There's 5 legs on this relay. Does that somehow come into the priming mode of the fuel pump?

 

The DME controls the prime vs run condition.





It's possible your relay failed closed.

 

Wow, that's very interesting information.

Seems like X10204 must wind up at the terminals of the fuel pump relay.

What would happen if the fuel pump relay failed in the On position? If that's possible? Would the key need to still be in the Run position for it to be running/priming? I'm trying to figure out if replacing the relay is worth it, or if that would just be a waste of money?

 

Yes. It's there in the diagram Daftlad posted. A6000 is the DME. M2 is the fuel pump. A1 is the BCM. It looks like the DME pulls pin 1 of connector X10204 in that diagram low to energize the relay. The most logical explanation to me is that the relay has failed closed. If it's removable, it seems like you could simply put an ohmeter on the relay to see if you have continuity without it being powered.

 

OK, that's exactly what I'll do! Thank you!

 

2006 MCS Fuel Pump relay

https://gethypoxic.com/blogs/technic...ertible-mcs-06

2005 : https://www.northamericanmotoring.co...pump-dead.html

 

I just had the realization that you asked a very important question that I didn't really consider. I don't know if F20 is ignition switched. If it isn't, it looks like the pump would run all the time if the relay had failed closed.

 

That's what I've been wondering. Obviously, the pump doesn't run when key is out of the car.

 

Okay, if I read the DIN Standard correctly, F20 is connected directly to battery positive (that's what the 30 on the fuse terminal in Daftlad's post means). So you were correct in wondering if it would run all the time. I'm guessing the relay didn't fail closed then.

The 15 above F34 means it is ignition switched.

Oof. Things just got more complicated.

 

Okay, here's another guess. If the issue isn't in the DME (which we don't know - it could be, but let's not assume the worst for now), you could have a short to ground somewhere in the circuit that connects to pin 1 of X10204.

Normally, the DME would hold that pin high after the initial priming period with the key on and the engine off - battery voltage on both sides, no running pump. With the key off, there's no battery voltage coming from F34, so also no running pump regardless of what pin 1 sees.

However, with a short to ground, there is 12 V across the relay if the key is in the on position, which would energize it without DME input.

 

OK, well darn. Looks like the relay is out for delivery today. I'll probably just try it anyways.