If your pump is original at 160k miles you are on borrowed time. Ours both failed at 133 ± 2. They are supposed to last 5000-6000 hours so 160000/6000=26.667 mph average.

The check valve is in the pump but the FPR on the filter also acts as a check valve so either failing will affect startup pressure.

You need to test pressure with a gauge on the rail. You can use an old school tire gauge but consider it disposable it will ruin the seals inside.

It should hold 30psi overnight. Also should be no wavering of psi at idle.

The FPR will obsfucate a weak pump for months or years. It's a lot of work to get pump outlet pressure at WOT so as pump slowly fails and output drops from ≈ 65 to 50 psi and the FPR hides the slow drop in psi over time.

When FPR or pump check valve fails, the hard start odds the main symptom

Hard/long crank is also a symptom of failing starter as they fail they take far more current but it should also crank slower.

Did I miss of you have i6 or v8?

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