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BMW 3-Series (E90 E92) Forum > BMW E90/E92/E93 3-series General Forums > Regional Forums > Australia > Fuel leak - something wrong or just overfilling it?



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      10-09-2018, 11:52 PM   #1
jzx_andy
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Fuel leak - something wrong or just overfilling it?

Hey guys, I have a strange issue which I think I've narrowed down to me repeatedly overfilling my E92 335i fuel tank incorrectly at United, but I'd rather be safe and gather some thoughts.

Issue came up immediately a couple of weeks ago after doing an LPFP upgrade and mixing some E85 at United. I definitely overfilled the car a little (made the pump trigger click 2 or 3 times all up) on the first occasion and the car dumped a litre or two of fuel. Didn't think much of it as I figured it was slightly overfilled.

Filled up the next week (upto around 90-95%) at a different servo. No issues or leaks.

Following week I filled up to 100% again at United (filled up to the first click and then stopped). Fuel leaked again, in the same manner.

The fuel leaks don't appear major (as they seem to stop completely after the car gets down to about ~90% fuel level), but they are a hazard, and I'm not sure whether I had inadvertently broken something with the initial overfill.

The fuel leak itself originates from around the rear end of the driver's side rear wheel well - there is a tube in that area that appears to run from the centre (or passenger's side) of the fuel tank to there. Anyone know if that tube is made to dump excess fuel and where it runs to? Is it a breather for the fuel filter?

Here's a pic of the rough area where it was leaking (I'll grab better photos of my car and with the guard liner removed if needed):



I've confirmed the fuel leak is indeed coming from the aforementioned tube situated in that area, and not the fuel filler neck/breather pipes that are more to the right and known to sometimes leak. No signs of any leaks whatsoever underneath the driver's side rear seat (LPFP location) or anywhere else.

Funnily enough, I added about 10L of fuel with a jerry can last night (to bring it up to about 95% and see if it would leak), but the car didn't leak at all even after a short drive.

Is there anything else I can check, or do I just need to be more careful when filling up? Haha

Any help would be appreciated!

Last edited by jzx_andy; 10-10-2018 at 12:03 AM..
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      10-13-2018, 06:34 AM   #2
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Originally Posted by jzx_andy View Post
Hey guys, I have a strange issue which I think I've narrowed down to me repeatedly overfilling my E92 335i fuel tank incorrectly at United, but I'd rather be safe and gather some thoughts.

Issue came up immediately a couple of weeks ago after doing an LPFP upgrade and mixing some E85 at United. I definitely overfilled the car a little (made the pump trigger click 2 or 3 times all up) on the first occasion and the car dumped a litre or two of fuel. Didn't think much of it as I figured it was slightly overfilled.

Filled up the next week (upto around 90-95%) at a different servo. No issues or leaks.

Following week I filled up to 100% again at United (filled up to the first click and then stopped). Fuel leaked again, in the same manner.

The fuel leaks don't appear major (as they seem to stop completely after the car gets down to about ~90% fuel level), but they are a hazard, and I'm not sure whether I had inadvertently broken something with the initial overfill.

The fuel leak itself originates from around the rear end of the driver's side rear wheel well - there is a tube in that area that appears to run from the centre (or passenger's side) of the fuel tank to there. Anyone know if that tube is made to dump excess fuel and where it runs to? Is it a breather for the fuel filter?

Here's a pic of the rough area where it was leaking (I'll grab better photos of my car and with the guard liner removed if needed):



I've confirmed the fuel leak is indeed coming from the aforementioned tube situated in that area, and not the fuel filler neck/breather pipes that are more to the right and known to sometimes leak. No signs of any leaks whatsoever underneath the driver's side rear seat (LPFP location) or anywhere else.

Funnily enough, I added about 10L of fuel with a jerry can last night (to bring it up to about 95% and see if it would leak), but the car didn't leak at all even after a short drive.

Is there anything else I can check, or do I just need to be more careful when filling up? Haha

Any help would be appreciated!
Sounds like the overflow drain
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      10-16-2018, 06:09 AM   #3
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Originally Posted by Socket View Post
Sounds like the overflow drain
Have the same issue. But after much investigation found out that this and a few models in the 3 series have a problem with the overflow/breather near the tank and rubbing on the chassis.you can now buy an upgrade part which stops the wear and the leaking.Easy job to replace although you need to drop the tank to get to itYou can do it yourself as I did and you only need to drop one side of the tank.You can buy the new pipe with a shroud around it to prevent further splits.($35)

Last edited by assassinsbrotherhood; 10-16-2018 at 06:15 AM..
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      10-16-2018, 02:12 PM   #4
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Originally Posted by assassinsbrotherhood View Post
Have the same issue. But after much investigation found out that this and a few models in the 3 series have a problem with the overflow/breather near the tank and rubbing on the chassis.you can now buy an upgrade part which stops the wear and the leaking.Easy job to replace although you need to drop the tank to get to itYou can do it yourself as I did and you only need to drop one side of the tank.You can buy the new pipe with a shroud around it to prevent further splits.($35)
thanks for sharing... people who are happy to share their experiences and solutions to help others out, is exactly what makes this forum is so great...
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