Looks like you beat the o-ring to expose itself. Yep put in ziptie. You can just slightly see it's starting to tilt toward letting o-ring come out.

It's "next level" test but I put the unit mostly in and run the fuel pump to make sure the bottom connection also not leaking it has no actual gasket.

I put in an o-ring on the bottom connection but don't bother if it doesn't leak it's a fair amount of work.

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