[tan_rich]

Hi all, first off I’m not sure if this is an issue but it’s something I noticed with the car and wanting to learn how the fuel system properly works.

After installing a bucket less stage 2 lpfp i’ve notice I have been getting sometime rough cranks/starts.

When I turn off the car after a few minutes my fuel pressure also dropped below 72 psi. To line 60 almost and to 50-30 sometimes. Sometimes when I turn on the car but not the engine after a few hours it’ll be 50-30 psi and a somewhat rough start. Sputter almost.

On WOT, my fuel pressure stays between 65-85 ish give or take. But isn’t steady, it’s jump back and forth a lot.

I don’t think the issue would be on the fuel pump itself since the fuel pressure regulator should be holding the pressure on the low side. Correct me if I’m wrong since I’m thinking the fpr is the problem.

Questions:
What should my fuel pressure be after 10-15 minutes after the car is off?
What should my fuel pressure be after a Few hours?
Should my cruising fuel pressure be irrational light that?
Should my WOT fuel pressure be fairly stable or being a jumping a lot normal?
How is the fuel pressure regulator controlled in our car?
Is it normal to see fuel pressure go above 100 psi sometimes from cruising or something. I assume it’s just happens when you give it a lot of load and the fuel pump reacts accordingly but the FPR should be good enough to bleed it out.


2013 335is DCT 90k miles, FBO for like 60k miles.
Mods:
Downpipe
Intercooler
Intake
Chargepipe w/ forge diverters
MHD flex fuel
VS stage 2 bucketless
Running e30-35 for about 9 months
Past 2 weeks have been e50
Thanks all