How do I access the fuel pump?

[LysanderSpooner]

Mom's '03 525i wagon died the other night and it's most likely the fuel pump. I will be changing it as well as the filter. The only video I found for changing out the pump shows it being under the car parallel to the drive shaft (and seemingly incorporating the filter), but Real OEM shows it being in the top of the tank with a separate filter that is where the 'pump' is in that video. I'm thinking they totally mistitled the video and it's really the filter they are changing out.

Then I found this video that shows the E39 sedan having the pump accessible under the rear seat. However on the wagon the rear seat is not just 'grip it and rip it' like in the video or for that matter on my E32. So how does the seat bottom come out?

screen-grab- 2022-11-12 at 6.23.04 PM.jpg screen-grab- 2022-11-12 at 6.22.38 PM.jpg

[KeysCoupe]

The rear seat bottom is attached at the leading edge. On each side, there is a plastic cover over a cast block. You have to remover the fasteners holding that cast block.
-Donny

[CPHES]

Yep - and that odd pair of clips is what you can slide the cargo cover into

[LysanderSpooner]

The rear seat bottom is attached at the leading edge. On each side, there is a plastic cover over a cast block. You have to remover the fasteners holding that cast block.
-Donny

That's good to know, thanks. Now how do I drain the ½ tank of gas that's in there?

[CPHES]

The access is from the top. I’ve done it on other cars - e38, R53, Yukon, Volvo, Saab, just be careful, no sparks, no cigarettes, open flame, etc. 1/2 tank should be fine.

[LysanderSpooner]

The access is from the top. I’ve done it on other cars - e38, R53, Yukon, Volvo, Saab, just be careful, no sparks, no cigarettes, open flame, etc. 1/2 tank should be fine.

That's what I thought too, just like on my E32. But I've seen some posters say that if the tank is more than ⅛ full that gas would go all over the inside of the car. Is this in relation to replacing some other part perhaps?

[CPHES]

As long as you let the pump drain out any remaining gas while inside the tank - once it is not mounted - let it drain out - I think you will be fine. Anyone else have a different experience?

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The under car with filter pic is for the fuel pressure regulator

[LysanderSpooner]

As long as you let the pump drain out any remaining gas while inside the tank - once it is not mounted - let it drain out - I think you will be fine. Anyone else have a different experience?

But if the pump is bad (which I suspect) it can't do any draining... Oh wait you mean drain any gas that is inside the pump before removing it from the tank?
- - - Updated - - -

The under car with filter pic is for the fuel pressure regulator

I will be changing the filter/FPR too. When doing that will gas want to drain out unless I block the flow somehow? Pinching the line from the tank will do the trick?

[CPHES]

The easiest way to dump pressure is to start the car with the fuel pump fuse out. But your car sounds dead due to the pump issue. Likely not much pressure left.

[LysanderSpooner]

OK I've got the new pump in but for the life of me I can't get the sending unit to seat back into place. It's hanging up on something on the way down and it's a good inch or more from going in all the way. All manner of twisting, jiggling, and swearing have failed me. What's the trick? And yes I have put the rubber ring on the tank first and not on the sender, so it's not that.

[LysanderSpooner]

OK I've got the new pump in but for the life of me I can't get the sending unit to seat back into place. It's hanging up on something on the way down and it's a good inch or more from going in all the way. All manner of twisting, jiggling, and swearing have failed me. What's the trick? And yes I have put the rubber ring on the tank first and not on the sender, so it's not that.

OK I answered my own question. The trick is to get so frustrated that you come back into the house to make a post about the problem, then go back outside and try again using the exact same tactics of twisting, jiggling, and swearing, and eventually you will get it to go in.

Come to think of it, this method has worked in the past on other issues too. Just the effort put forth in posting seems to appease the gods or sumpin'...

[dohalloran]

Yep. '03 wagon here as well. I had well over half a tank when I did mine. Sometimes you have to step away from a problem, like you did, and then go back it. I remember the pump requiring just the right amount of "twist" with the way the wires were in there.

[LysanderSpooner]

Car ran fine after the pump swap, but after changing the fuel filter with a new Mann unit it's idling rough and way down on power. I removed fuse 22 to the fuel pump and cranked it over a few times to remove pressure before doing the filter swap. I've read about a Schrader valve to bleed off air out of the system but I don't know where it is. I might also suspect the vacuum hose to the fuel pressure regulator but I don't know where that connects in the engine bay. When I pulled the hose from the old FPR I'm wondering if I didn't yank it loose somewhere upstream.

[LysanderSpooner]

Car ran fine after the pump swap, but after changing the fuel filter with a new Mann unit it's idling rough and way down on power. I removed fuse 22 to the fuel pump and cranked it over a few times to remove pressure before doing the filter swap. I've read about a Schrader valve to bleed off air out of the system but I don't know where it is. I might also suspect the vacuum hose to the fuel pressure regulator but I don't know where that connects in the engine bay. When I pulled the hose from the old FPR I'm wondering if I didn't yank it loose somewhere upstream.

I decided to do a reset by disconnecting the battery and <Voila!>, car runs better than it ever has in the 5 years we have owned it. A lot of black crap came out of the old filter, and I'm guessing the computer had to learned how to deal with the minuscule amount of fuel that was trickling through it.