I can totally relate, but I think the newer ones and the replacements have been improved. I agree with the screw idea for extra safety but a person would have to be careful not to have the screw push the connection too far in the opposite direction. I know you don't agree, but I still think a back-up ring and maybe a zip tie or something to hold the thing straighter would be the cat's ass. It would be really nice to know for sure if there was an improvement in the newer/replacement ones.

Faster when fuller? What is going on?
 

There is no advantage to a second ring if adds no purpose.. If it held the thing straight it would do the trick but I simply put a zip tie around the other side to act as a lever to push the side with the o-ring tighter and it works.

But putting a screw on that side on the low pressure side of the o-ring it won't have to go through into the high pressure pipe just a "dent" that it can grab so no issue with creating a leak. It will hold it perfectly straight for a million literal miles

I haven't seen newer designs in person but from pictures online of current models for sale it appears the flaw was never fixed

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Another interesting thing, maybe I am in the twilight zone, but what the heck is with the stainless screw in the rounded foot of the syphon jet side fuel sender ? I agree the fuel system is pretty awesome, including the spring loaded reference fuel senders!

Your not understanding what I mean by backup ring. Maybe google it, commonly used in hydraulics. I see your theory on the screw but it would need to be on the opposite side of where the o-ring fails correct ? Or maybe a screw on each side to keep things centered, or maybe a back-up ring! ;)

I just read your comment on the backup ring it has some sound science behind it but it would only help no guarantee.

The screw I'm describing would hold the thing absolutely to prevent the o-ring from getting crooked at all. 100% cure so no need for the positioning ring.

https://uploads.tapatalk-cdn.com/201...a73e581faf.jpg

Red arrow points to where I would add a screw: the left side is held fine by the clips the right side is not held at all.

My quick fix was to add a spacer were the yellow arrow points to act as a lever and push the left side down to hold the right side up it seems to work well but longevity who knows?

The green oval marks the unlisted seal that also leaked on every BMW fuel system I've worked on so also a design flaw. Any leak there will reduce the effectiveness of the siphon jet and therefore reduce the hours the pump will last. This is also the joint where the check valve is located.

The blue oval marks the o-ring connection and that joint is easy to open and work on to repair.

I would need to see the picture of the screw at the bottom but I would guess it's holding the foot to the spring steel rod that holds the foot in place


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I have read this post and the "Fuel supply detail" post from andrewwynn several times. I have learned a lot, but am still confused about a couple things.

First and most importantly, what preemptive maintenance is appropriate for my son's e53 with roughly 150K miles? The in tank fuel pump will eventually wear out, so replacing the pump or the fuel sender unit seems reasonable, but what about on the port/siphon side? If I understand the posts correctly one can have a nice new pump/fuel sender but still run out of gas with roughly 1/4 tank - correct?

So how to prevent this? One option is to replace the siphon assembly, but that's expensive. The only "wear item" I see in the siphon assembly is the o-ring (part #4 of this realoem link).


http://www.realoem.com/bmw/images/diag_3adr.jpg

I have read about backup o-rings, replacement o-rings, drilling holes, stainless flat head screws 3 mm, clamps, zip ties, and teflon tape. I have looked at the picture on post #25 but I'm still confused.

Any more detailed explanation? Perhaps additional pictures from different perspectives? Sorry if I'm being stupid, and thanks for all the work on this issue - it is much appreciated.

In addition, I have also read the "fuel delivery problems" posting that is here. However, I am still unsure of how to prevent problems with the siphon system. I see the folded up o-ring, but it is implied that merely replacing the o-ring is an inadequate fix. There is mention of teflon tape, but I don't see where it is applied. I see the zip tie, but don't understand what its purpose is - to hold something tight, or just to prevent the male/female plastic pieces from overlapping too far and causing a twisting of a different nearby connection? No mention of a screw in this posting. And, by the way, what kind of a screw are you talking about? Machine screw with a nut or a wood screw? 3mm thread, correct? And, again, where would this screw go?

Sorry if the solution is staring me in the face and I can't see it.

It is confusing. The best thing you can do is pull it apart and have a look and maybe take some measurements. It becomes a lot easier to understand when you have it apart and it is an easy job, just be a bit carefull with the plastic especially the hose nipple and have a replacement hose clamp ready. If the o-ring is not pushed out it will be fine to re-use and like andrew said, I wouldn't mess with the clip together portion that doesn't have a seal if it looks good. Again will become obvious when you have it in front of you.

I should say that both clips that hold the stiff wire portions on need to released at the same time.