[German_E92]

Maybe it looks that way. The spring is designed for 72psi, if the pressure is higher a return line is exposed and fuel can flow into the tank. If the pressure of the fuel pump drops the pressure regulator closes the line to the pump.
Could this be the function?

[woo102]

How long is the high pressure fuel rail supposed to maintain pressure after turning off the engine?
Mine is dropping to ~90 psi a couple of seconds after turning the car off.

[marcoxtv]

Originally Posted by nukezero

I've been chasing a long crank issue since my turbo wastegate failed due to worn bushing. The turbos are fixed and the car performs superbly when running but it's been suffering from constant long cranks 3-6 seconds long. Doesn't matter hot or cold. I still get no codes other than 2AAF.

I finally had a chance to data log it with Bavarian Technic tool and interestingly this is what I found.

X-axis is in seconds. Y-axis is in PSI.

Is this conclusive proof that my HPFP or LPFP is failing? As you can see, the engine speed (when I push the start button) begins at around the 30 second mark. As the engine is turning over, the lpfp (fuel low pressure) does not hit 67 PSI until 31.8 seconds mark. Meanwhile, the HPFP has almost no pressure until the 32 second mark.

The rail pressure(hpfp) and engine speed is on the left y-axis. The lpfp is on the right y-axis.

When I did this log, the engine was previously already started. So there was pressure in the fuel rail. Is the fuel rail supposed to lose so much pressure after a shutoff that it goes almost back to 141 PSI a few seconds later ?

Is this indicative that the HPFP is just not holding fuel rail pressure? I've already done the injectors (index 12) on all six a week ago. Mind you the car runs superb when it cranks up. No faults.

FIXED!! It was the fuel pressure regulator! UPDATE BELOW!

Did your lpfp prime when u opened the door or unlocked the car because mine is not doing that and its cranking for long just like yours