[ACETG2000]

I just replaced my lpfp with a walbro 525. I’m stage 2 on MHD, but I can’t get past 4k rpms without my lpfp going below 20 psi. The pump is brand new so I doubt it’s faulty. Do I need to run bucketless or what could be causing this?(no codes) Here’s the log
2008 bmw 335i 6mt

[RockCrusher]

Off hand I'd say the LPFP doesn't have the capacity to supply sufficient fuel volume at the necessary pressure.

Not sure what bucketless refers to.

What I did when I modified a car engine among other things I replaced the dinky 2 barrel carb with 2 dual side draft Weber cars with 45mm throats -- I eliminated the engine mounted fuel pump and fitted an electric fuel pump at the tank, out side the tank but located to protect the fuel pump -- and ran a larger fuel line to an adjustable fuel pressure regulator. I used a fuel pressure gauge to set the fuel pressure regulator to the pressure called for by Weber. No problems.

I don't know if there is higher capacity fuel pump that could replace the current LPFP -- which I assume is in the fuel tank -- or if you might have to fit a bigger pump outside the tank.

[M2guru]

My understanding is that the LPFP number is an extrapolation. This is why I hooked up a true LPFP fuel pressure gauge. Because it's not the true number, I'd suggest digging into what goes into that number. Maybe it's partially the HPFP number (which is actual) that goes into the number. Sorry I cannot help more - just don't know more than that.

[Jodedor]

I could be way off, but isnt this post in the wrong forum?

You said 2008...this is the G80 forum.

[ACETG2000]

Sorry, I’m new to the app I will get in the right forum. I filled the tank up with some fresh gas and apparently the problem went away but still seemed weird when I had around 1/4 of a tank still left at the time of the pull. Thank you for the help!