So I'm concerned that you got 40psi. Afaik it's supposed to be 50 i don't know how it started with 40psi. I think the type of injector just uses math and pulse timing with 50psi assumed.

Any chance your gauge isn't reading correctly?

I'm really not aware of cases where FPR will fail to a wildly different value and still regulate but you said both steady output and holds over time so it's not the o-ring.

I'm wondering if the way the ignition switch is wired, they use a separate parallel set of contacts for determining when to send power to the fuel pump.

Relay is far less likely to intermittent fail than the pump. Did you say you replaced the pump?

The FPR will hide a failing pump for a very very long time (months if not a year or more) so it's not uncommon for an old pump to give you the exact symptoms you describe.

If you are running E10 gas the life expectancy is 5000 hours. Multiply your average speed (typically about 20-30) by 5000. Eg 27*5000=135000

Wife's car had average speed of 27 and the pump failed at 133,000 133000/27=4925.926 estimated hours!

If your pump is over 5000 hours it's overdue for replacement.

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