Fueling issues help needed

[AndyW]

Was wondering if the collective here lend me your expertise on BMW fueling systems to help me determine if my LPFP (1 year old fuel-it 525 stag 2) is dying or if something else is going on, as well as how to check if my in-tank fuel setup is correct). Recently my track 135i (2012) has had some fueling issues(fuel rail pressure bottoming out), and in troubleshooting I ended up replacing the HPFP and installed a bypass kit for the EKMP3 module (to eliminate that overheating as a possible problem). Symptoms changed after HPFP replacement so I am pretty sure it was going out (110K old). The car now has an intermittent issue with a new symptom (2BE9 - Cylinder injection cutout: Pressure too low in high-pressure fuel system) that causes the car to go into limp mode on track. It appears is only occurring on left hand turns so maybe somehow the bucket isn’t staying filled? Not 100% sure of the correlation, but it’s a working theory based on my limited knowledge of the fuel tank component functions. To complicate things, I have the FPR replaced earlier this year but did not do the work myself so I am not sure what “right looks like” in routing all the hoses to the correct spots. Any help appreciated.

Here is a recent log with the fuel rail pressure bottoming out. https://www.spoolstreet.com/graphs/...og-2-limp-mode.20963/?series=19&zoom=-39,3925

Best,

Andy

 

[Bnks334]

Was wondering if the collective here lend me your expertise on BMW fueling systems to help me determine if my LPFP (1 year old fuel-it 525 stag 2) is dying or if something else is going on, as well as how to check if my in-tank fuel setup is correct). Recently my track 135i (2012) has had some fueling issues(fuel rail pressure bottoming out), and in troubleshooting I ended up replacing the HPFP and installed a bypass kit for the EKMP3 module (to eliminate that overheating as a possible problem). Symptoms changed after HPFP replacement so I am pretty sure it was going out (110K old). The car now has an intermittent issue with a new symptom (2BE9 - Cylinder injection cutout: Pressure too low in high-pressure fuel system) that causes the car to go into limp mode on track. It appears is only occurring on left hand turns so maybe somehow the bucket isn’t staying filled? Not 100% sure of the correlation, but it’s a working theory based on my limited knowledge of the fuel tank component functions. To complicate things, I have the FPR replaced earlier this year but did not do the work myself so I am not sure what “right looks like” in routing all the hoses to the correct spots. Any help appreciated.

Here is a recent log with the fuel rail pressure bottoming out. https://www.spoolstreet.com/graphs/...og-2-limp-mode.20963/?series=19&zoom=-39,3925

Best,

Andy

Did you ever figure this out? I thought it was my hpfp because I replaced my old one with an Amazon special. I had been getting rail pressure dips. The rail pressure dip is gone now but now i am getting the 2be9. Looking at logs the rail pressure is dumping to 0 when this code is thrown. I have a walboro 450 in the bucket and the bucket was staying full when supplying 12v to the pump in testing. I am guessing it's a lpfp issue still though since rail pressure tanks below 75psi lpfp.

Guess I'll just try a stock lpfp.

 

[AndyW]

Did you ever figure this out? I thought it was my hpfp because I replaced my old one with an Amazon special. I had been getting rail pressure dips. The rail pressure dip is gone now but now i am getting the 2be9. Looking at logs the rail pressure is dumping to 0 when this code is thrown. I have a walboro 450 in the bucket and the bucket was staying full when supplying 12v to the pump in testing. I am guessing it's a lpfp issue still though since rail pressure tanks below 75psi lpfp.

Guess I'll just try a stock lpfp.

Well, through a lot of troubleshooting, I ended up replacing the 525 with a 535. I also had some poor electrical connection issues with the bypass kit - had to resolder. Believe issue was a combination of both problems - failing pump plus high G movements would cause wires to shift in their plug (one wire basically was down to two strands and had melted the plug). No issues now with the 535 and all wiring connections redone.

 

[Bnks334]

Well, through a lot of troubleshooting, I ended up replacing the 525 with a 535. I also had some poor electrical connection issues with the bypass kit - had to resolder. Believe issue was a combination of both problems - failing pump plus high G movements would cause wires to shift in their plug (one wire basically was down to two strands and had melted the plug). No issues now with the 535 and all wiring connections redone.

I only spliced 2 wires. I cut the Walboro generic plug off and spliced on the connector from the stock LPFP. I can't see how the splice could be the issue. Maybe the stock connector is the problem if wiring is the issue. I am getting the same cause as you though... high G movement (autocross). It works perfectly fine on the street ripping the car doing pulls. I really don't think it's fuel starvation because I had 0 issues half way through both autocross runs until... boom rail pressure cut to 18psi almost like the LPFP just stopped working. 1/2 tank at the time too.

Maybe faulty pump? I guess I'll just have to keep messing with it. This is killing my season!