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stonex1 04-17-2020 10:50 AM

Fuel leak? or fuel breather?
I finally got my X1 out of the garage from winter storage, but the night before I noticed a fuel gas smell coming from the passenger rear wheel well. It looks like there could be a stain on the inner liner behind the wheel.
There is no other gas smell in the cabin, or engine bay.
There are no signs of leaks anywhere on the ground or anywhere else near the rear suspension.
When I smelled the fuel in the wheel well, I realized the gas cap filler was right there. So I opened up the cap and pssshhhhh. A bunch of pressure released for about 4 seconds. No liquid, just the sound of pressure coming out.
I filled my tank right full before winterizing it in the garage.

I've noticed today that the stain on the wheel well liner is starting to dry up.
Do BMW's have some kind of gas tank breather valve that would release fuel if the pressure built up too much, or have I blown a leak somewhere?

EDIT: checked and it does look there is a vent hose part, so I'm hoping that's all it was and some pressure built up and it released some fuel.
Will keep an eye on it to see if it releases or leaks fuel again.

stonex1 05-19-2020 06:18 PM

Just wanted to post an update on this issue.

After running the car for about a week without issues. I had a check engine light come on.
I cleared the code using ISTA-D and ran it for a few more days. After about another 5 short trips the check engine light came back. So re-scan for fault codes and it showed the famous DMTL pump fault.
(Diagnostic Module Tank Leak) I ordered a replacement part online and swapped it out.
The original part was dripping with gas, and it must have failed over the winter and leaked fuel up into the dust vent that is right near the wheel well. That was the reason for the leak in the first place.
I likely overfilled my gas tank before I parked it for the Winter. Pressure built up when the weather got warmer.
I have run the car now for around 10 days since putting in the new part and haven't seen the check engine light return.
The part at BMW is $315 CAD but found it online for $150 CAD.
Easy part to replace, it's just up behind the rear bumper. No need to jack the car up or anything.

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