udfxrookie

2009 535i xDrive (N54)
I had a walbro 450 but had very very low LP pressure 20-35... Swapped in a new 535 and have the same low pressure... It has a new filter/regulator from FCP and I tested a new ekp3 unit.... Still low pressure.... What could be the issue?
Think I got a faulty regulator/filter setup? What can I try/test?

I tried my old FPR/Filter and got 38-39 on WOT
DataZap Log

This produces code:
29DC - DME: Cylinder injection cutout.
MHD believes it to be because of the low pressure from my LPFP

udfxrookie

anyone?

seanjordan20

I'm thinking the regulator. Had that issue before and I found a write up about it. If I remember correctly the regulator is a common fault.

udfxrookie

Ok.... so I installed a NEW LP Sensor, and NEW 535 pump with a NEW filter/regulator on the drivers side and STILL my LPFP psi is 40-46, 5-6lbs of boost (stock) at WOT.
Can anyone tell me what to look at.

Hopefully someone can figure out what I should be looking at when I have all new stuff in the tank.

udfxrookie

Checked the hoses by air compressor/water bucket test lol. I had both ends outside the bucket and blew air through all lines (to ensure no actual line pressure)
The ONLY part that had air bubbling was from the top of the second photo which appears to be part of some...ball/spring mechanism. The top hat of the bucket
I bought on ebay that was from a 09 535i (not xi like mine) does NOT have this "mechanism" so there is literally NO air leakage. This is literally the only part I
have NOT swapped out so I will be doing this tomorrow morning and reporting back.... praying it's a replacement part the previous owner used and they got the
wrong one since I've had low pressure since I bought the car.

twh

535i and 535xi take the same part. I'm guessing the part you got from eBay wasn't what was advertised. Look for part numbers on the assembly.

udfxrookie

THAT was it, the part I got from eBay WAS actually from a 535i/xi and the one that was in the car (from previous owner "fixing" it) when I got it was from an NA.
A friend chimed in when he saw the top hat: "You've found the fuel leak. Looks like someone incorrectly installed the part that has the fuel pressure regulator. This part is intended for the non-turbo cars that use the fuel pump relay. The turbo direct injected engines use the EKPS fuel pump module that doesn't need the pressure regulator. ~ pshovest"
I'm getting normal 70+psi now!!!