Fuel tank pump issue, level sender issue
 

2006 4.8is 2/1006 build date..

I figured I would ask before I spent more money. Vehicle started one morning ran for a second and quit. Crank, no start. Okay. Needs, spark, fuel, air. Fuel gauge reads 1/4 tank, but I don't hear fuel pump. Spray starting fluid in intake it starts. Got to be fuel pump issue. Pull rear seat, pull connector and test for voltage, no voltage to pump. All pump related fuses good. Switch horn relay with pump relay, same part, still nothing. Put voltage to pump and still no pump. All these test done alone, I really could have used a second set of hands. Figured I would just pull the pump out anyways. Put voltage directly to the pump out of car, no pumping. Figured previous test due to me being alone and not getting good connection and pump was bad. Ordered new electric pump and replaced it. Was going to put it back in and realized their was only a little fuel in the sump of tank.. I thought back since I had just parked it when the problem arose and think I had put fuel in it soon before this happened. So I thought maybe bad fuel level sender. Plugged assembly back up out of tank and manually moved float from full to empty position, never registered empty. Thought, okay, bad sending unit. Then I looked on real OEM to see the entire in tank assembly. It appears to show a line connecting to the right side assembly around the fuel level sensor, mine doesn't do that nor have somewhere to attach..? Searching online in a few places it appears there is also a level sensor on the left side..?

So, after this novel I just wrote explaining where I am. My questions are. Is there a sending unit on the left that works in conjunction with the one on the right for fuel level? But also, and more confusing. How is the fuel transferred across the fuel tank hump to the from the left to right side where the pump sump area is? The real OEM diagram makes it more confusing showing the line from the left side of tank to the right side connection to the fuel pump assembly which mine does not nor have a location to hook up..?

I just pulled unit out of left side of fuel tank.. There is fuel as well as another fuel level sender.. The unit only has two small two small wires and they go two the sending unit. There is no pump and as stated the hoses from left side of tank to the right so not connect to the only electric fuel pump in the tank. How is the fuel transferred and what is causing it not to transfer from left side to right?

Find my detailed master thread on the fuel supply for the e53. Search for my username as started by. awr-fix should also be in the title. There is literally no more detailed description on the internet. Not even from BMW. They copied boilerplate from 5 series that doesn't apply to X5.

Some of the top points:

1) the electric pump is on the right side
2) the pump pushes fuel at roughly 65 psi to the fuel pressure regulator and filter
3) the FPR sends 50 psi to the fuel rail
4) the excess fuel pressure is used to send fuel at ≈ 18 psi back to the left side of the tank
5) the flow back to the left side goes though two venturi valves to suck fuel from the front and back to the pump well on the right side
6) there is a design defect that will eventually cause that Siphon jet to fail. Usually by 15-17 years or 130,000 miles. That can be fixed for a couple $ vs. replace the whole pump
7) when that fails you will fuel starve the engine when about 1/4-3/8 tank
8) once you are lower than about 28L of gas the car only "sees" about 5.0L of fuel, about 3.6 of that is not registered on the gauges.
9) the fuel filter is for all practical purposes lifetime, it can easily last 400,000 miles. However the FPR has an o-ring that will fail causing low and unstable pressure. They are usually sold as a unit.

Tell me more about this please.
Fixing this for less monies.
I'm experiencing the 1/4 tank situation...I just changed out the fuel pump. But I don't want to experience this in the future...she has the e83 x3.

Simply said. It draws it from one side and returns it to the other. Right side has the pump which has 2 suction lines connected to it. The return is on top of the pump and the feed is on the opposite side.
2 level sender units. Check my post to see the replacement parts you’ll need. You don’t need the whole assembly!

Any more questions just fire away I’ve got mine out right now!

Question 1 what part is essential to replace?

It’s these that simply wear out over time
https://i.postimg.cc/GtxqtDt8/043-E2...-D08-A35-E.jpg

Yhis is extremely helpful...
Are they sold...?
I take it the sender arms swivel/slide here?
What are they called ?

The resistance board for the level aren't a part I'm aware of sold. They can be cleaned and the wiper can be bent to increase pressure to get those working.

When that fails the symptom will be the fuel gauge will not go to full. The runs out of gas at 1/4 tank is a very different problem. That happens when the o-ring seal on the "sending unit" fails.

I like to see the location on the sending unit ....
Would I find this in the tank with the pump? Just trying to understand at rudimentary level.
Thanks

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I found one person who sels the parts separately! He’s from Ukraine. In total I paid about 25€ including shipping!

I can ask if he has more. They actually worked and since the oem parts cost a ridiculous amount of money it was worth it to me to take a gamble on them.

Yes on both sides. Next to the pump as well.

https://i.postimg.cc/qBQnZVb0/IMG-3290.jpgafbeedingen

AWR-fix: Fuel Gauge Sender Repair (fix errant fuel gauge)
https://r.tapatalk.com/shareLink/top...ink_source=app

The process to repair an errant sending unit

I've got to go to my neighborhood bone yard to experiment on location, removal and dismantling[emoji106]

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AWR-fix: e53 Fuel pump / siphon pump details
https://r.tapatalk.com/shareLink/top...ink_source=app

The definitive guide on the fuel supply of the e53. much of which is in most BMW with some significant differences like some sedans don't have an actual sump for the pump though BMW will refer to the zone where the pump is located as the surge tank it's just baffles to keep fuel near the pump during g-forces like turning and braking, however they won't hold the fuel during high angle of attack (pitch).

The OP needs to take a step back and diagnose a bit more methodically. He supposedly has no power to the fuel pump, the fuel pump is no good, the sending unit doesn't work and the syphon jet doesn't work (or isn't there) and he's wrong on most of those assumptions. The pump won't work if there is no power, the guage won't necessarily respond directly to working the float up and down, there is a small amount of fuel in the fuel pump well which might be normal, etc.

So we will not use this e83 as reference

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Lets not, the E83 is a lot different.

Yeah not remotely similar. Go read my threads there is no better reference online or otherwise


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Was not aware...[emoji106]

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He replaced the pump. Comfort start will not apply power to the pump until your turn the key.

I think he got the car running now just trying to get the siphon jet working so no more dead in the water at 1/4 tank

I actually came to a stop and posted this thread. I became confused after looking at the real OEM site and knowing my vehicle did not have any of the cross over hoses attached to my pump assembly as shown. When I opened the left side of the tank and saw fuel and another level sender and no type of pump I shut the door and slept on it. After reading your post you have confirmed my thoughts. That is that the return from the filter back to the left side assembly creates the pressure to transfer fuel left to right. I would like to know your thoughts that I have that possibly the right side level sender registers 1/4 to full, as it did when I manually moved it through it's range, and when it bottoms, the left side sender takes the fuel level from 1/4 to empty?

The full gauge reading is the sum of the readings from the two halves of the tank - it is not that one sender is part of the range and the other is another part.

If you unlock the cluster menu you can see the actual sender values in test #6: -

https://i.ibb.co/1dqgYxK/OBC-TESTS-4-7.jpg

https://i.ibb.co/RQVb9ks/Test-6-Fuel...ow-Cluster.jpg

https://i.ibb.co/3NgFcr3/OBC-TEST-6-...el-in-tank.jpg

https://i.ibb.co/R7JGFkD/OBC-TEST-6-...-in-Tank-1.jpg

(pics all thank to Qsilver7)

Remind me how to get into that menu if you will. It's been awhile since I have done it. And your explanation of the sum of both sends the level to the display makes sense.

This video shows it - but all you do is enter the BC (hold right button down until Test No. 01 appears), use right button to step to menu 19, press left button once, then enter the sum of your VIN numbers (using left button) and press right button.



https://youtu.be/iVabtlbhCdc

RH drive puts the left/right backwards? I've always wondered what's going on there. Your tank isn't opposite is it? Electric pump left vs. right? The normal tank display is left/right/total and unless something is broken it's impossible to have 0 on the right and anything on the left.

The right will drop to about 1.5L when the left is about 27L. The left will drop to zero then the right will drop to zero. At that point about 3.6L left but the internal reading will be zero and DTE will stay zero.

There's not much swapped over in the LHD/RHD versions - just the driver controls mostly. The signal and wiper stalks aren't even swapped over for the RHD (good thing I have an auto, or changing gear and operating the signals while cornering, all with the left hand, would be a mission!).

And the tank is identical on both LHD/RHD versions of the e53. If you are referring to the (Russian?) video - maybe the car is an e39 - not sure. :dunno:

What I do know is my own RHD e53 operates exactly as per all your research indicates for the LHD versions, in terms of tanks emptying rates etc.

Well, almost exactly. It seems that when pumping diesel fuel the electic fuel pumps last a lot longer and the o-rings don't seem to swell or distort as badly.

https://uploads.tapatalk-cdn.com/202...04ee650ab2.jpg
I'm referring to this picture which I just noticed is attributed to qsilver. This cant happen without malfunction: left side less than right (other than when less than 1.4L).

Yep - understood but I also don't know what car this image is from - could be another e39 etc. - Qsilver7 posts on a number of different vehicle forums/threads.

I think the e39 tank(s) work in a similar way to the e53 but the plumbing is a bit different. Not sure - hard to study as I don't have one and it seems no e39 forum has a resident ARW. ;)

I should have searched longer to find an image I *know* to be from an e53. ;)

Most likely those previous cluster images are from E39 (or E38). It has a symmetrical saddle tank and the left side is almost totally transferred to right side when the tank is near half (in diesel models if the in tank pump is working correctly).

E39 I've worked on and changed pump. It does have a saddle tank but does not have the deep well for the pump which is a big improvement for taking turns and hills.

In researching the e53 fuel supply found plenty of posts where e39 drivers would take a hard ledt turn to slosh fuel to the right side at the first sign of fuel starvation. That's really not going to work on e53. The trade off of the deep well is by the time that is dry there's no warning