To confirm o-ring failure open up the left side and lift it just a little bit. Wrap with shop rags you can burn if gas sprays and just turn the key to on.

The pump will prime and send fuel back to the siphon. If the o-ring has failed it will spray sideways.

(And directly into your iphone if you happen to be recording to shown to others).

If you pull out the sender unit it's usually quite obvious when the o-ring has failed it will be pushed out of its groove.

Some times the o-ring itself will fail and leak without visible clue though so the only way to be sure is key on while observing.

You can be 99% sure just from reading test six.

When total fuel is below twenty eight liters, the right side should stay at ab9ut one point four liters. If it drops to zero the siphon pump is not working. Almost always from o-ring failure but can also be from the electric pump end of life so it's not one hundred percent.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)