[taylorchuck]

Im having a hard time figuring out whats going on with my car. A little over a month ago I was having a problem with my car not starting after I used INPA to try to fix my comfort access. It would crank until the battery died but never start. I thought fuel pump at first but I could hear it prime when I get in the car. I was getting codes got EWS-CAS not communicating so Im thinking It would be a quick sync and Id be good. Turns out thats not a thing for the E90/N54 platform. So I gave in and took it to a BMW specialist. And heres where things really turn sideways.

So the shop tried to sync the modules, that didnt work. They said theres a problem with the CAS and its pretty much toast. So they had to order one from BMW and code it as a new unit. Well turns out at some point before I owned it, the car had the FRM module go bad and the previous owner replaced it with a used FRM. I guess they never had it coded properly when it was replaced, because the specialist that was working on my car said that the FRM on my car is showing a different VIN number than mine. It wouldnt be a big deal, EXCEPT they say that they cant write the new CAS module if the FRM isnt correct. I never knew that to write coding onto a CAS module, it has to go through multiple modules to verify that its correct or something like that. At least thats what they told me. I asked if they could just rewrite the FRM that was in it since it was functioning properly, they told me they couldnt but they had a guy that could come to their shop and do it. It was $945 for a new one or $700 for the guy to rewrite the one I had, which I thought was crazy for more than one reason.

So they replaced the FRM and coded the CAS to my car. Well it didnt fix anything. They said there was no pressure coming from the LPFP, and it would need to be replaced. I told them I would let them know, so they decided to put a new pump in it to see if that was the fix and said that there was pressure on the low side, but now the high pressure fuel pump wasnt putting out any pressure. I ended up picking up my car and taking it to the shop I work at. Found out a wire on the low pressure fuel pump had broken, so I repaired the wire and can hear it kick on when I put the key in. That didnt change anything so I thought maybe Ill try the HPFP since I know they can be a problem. I replaced it earlier today and still get the same thing. It cranks but wont ever turn over. I checked the fuel sending unit on the drivers side of the tank because Ive seen a few cases where a hose comes loose on it and prevents the pump from building any pressure. There was a hose that had popped off the connector, so I put it back in place and still get nothing.

I do know Im getting spark, because I sprayed some starting fluid into the intake and got it to fire off a little bit. Im still wondering if theres something going on with the computers not telling the injectors to fire or something like that. The shop that replaced the CAS module told me that when they were finished writing the modules there were no codes on the car. At this point they were trying to sell me on another $1600 worth of fuel pumps so it feels like they were telling me all this so Id believe that replacing the pumps would fix it. When I got my car back from the shop I scanned it with an AUTEL diagnostic machine and it showed faults in 6 or 7 different sections, 2 being the FRM and CAS. I work for a mechanics shop, so I know my way around a car. This is my first BMW so Im still getting familiar with the electronics and stuff, but I mean so far theres not much else I can think of besides the injectors arent firing, and I would assume thats controlled by a computer. Im really getting to the end of my patience with this one but I dont want to take it to another specialist so they can sell me a bunch of stuff I dont need again. If anybody knows where to look, I would really appreciate it. Hopefully Im missing something stupid.

[lowrydr310]

Do you have INPA? If so, you check the low pressure side fuel pressure to see if there's pressure at the rail (inlet to HPFP.)

You might have a faulty EKPM. That's the module that controls the fuel pump. Unfortunately I don't know how to diagnose any issues, but the DME commands the EKPM.

I haven't been able to find much info but I'm dealing with a possibly related issue. My car runs fine and data logs show no boost, timing, or AFR problems, however my low fuel pressure never goes above 50 and is all over the place, it drops down to the 20s sometimes, even a few spikes down to 10. I installed a new fuel pump and that made no difference. Next up is a new regulator which I've yet to install. I'm thinking the regulator assembly might be cracked and bleeding pressure, a bad regulator, or a cracked hose inside the tank. I also have an updated LP pressure sensor and a spare EKPM if needed.

[taylorchuck]

I do have INPA but I’m afraid to use it now. This whole thing started from me using INPA to try and find out why my comfort access wasn’t working. After trying to scan my car, it just wouldn’t start. Changed the low pressure fuel pump today and it changed nothing. I’m actually not even getting fuel to the rail. I broke loose one of the lines going from the rain to the injector and nothing came out. This was after i tried cranking it for a minute so i know the low pressure pump had primed. I starting to think whatever controls the high pressure pump is bad. The HPFP is brand new.

[taylorchuck]

Ok so heres my next question. Is there a sensor in the fuel system that could be causing the HPFP to not run? Im really not seeing what else it could be other than a programming issue or a fried DME. I wasnt sure if theres a way to prime the fuel lines or if it was even necessary. I was hoping someone with knowledge on how the fuel system works would be able to give me some insight on whats missing from my equation. Definitely not getting fuel to the rail. LPFP and HPFP are brand new. I can hear the LPFP prime when I get in the car, but nothing gets past the HPFP. If I take off a fuel line from the rail to the injector, its dry. So what else besides a faulty fuel pump would cause fuel to not pump through the HPFP? What module controls the HPFP and what fuses do I need to look for in the junction box?

[gbalthrop]

Originally Posted by taylorchuck

... A little over a month ago I was having a problem with my car not starting after I used INPA to try to fix my comfort access. It would crank until the battery died but never start... I was getting codes got EWS-CAS not communicating... So they ["BMW specialist"] replaced the FRM and coded the CAS to my car. Well it didnt fix anything... I do know Im getting spark, because I sprayed some starting fluid into the intake and got it to fire off a little bit... When I got my car back from the shop I scanned it with an AUTEL diagnostic machine and it showed faults in 6 or 7 different sections ["sections?? You mean Modules??], 2 being the FRM and CAS. I work for a mechanics shop, so I know my way around a car. [See BELOW]...

Originally Posted by taylorchuck

I do have INPA but I’m afraid to use it now. This whole thing started from me using INPA to try and find out why my comfort access wasn’t working. After trying to scan my car, it just wouldn’t start...

YOU/ WE CANNOT Diagnose your issue WITHOUT:
1) Fault Codes, and then
2) Live Data.

INPA will give you BOTH. If you have a proper INPA installation, and use it correctly, there should be NOTHING to fear about "screwing something up". Throwing parts, and NOT using Diagnostic Software has done NOTHING so far. You have NOT mentioned even ONE Hex-code/ DTC/ Fault Code. If you get an INPA "Error Message" at any point, save & Post a ScreenPrint of that error message, together with WHAT menu choice you had selected Before the error message appeared.

Your 2008 N54 with MSD80/81 has TWO sensors to detect fuel pressure:
1) Low Pressure Fuel Sensor that detects pressure from Low Pressure Fuel Pump, in 72 PSI range;
2) Rail Pressure Sensor, that detects pressure at Fuel Rail, where HPFP SHOULD greatly increase that pressure.

INPA can read BOTH values/parameters from those sensors with Ignition ON, and/or during Starter Cranking. To view/ Save/ Post ScreenPrint of that Live Data, follow this Menu Path:
INPA > DME (Engine | N54 (MSD80/MSD81) > F5 Status > F2 Analog > MWB 1/ 3/ 6 (Measured Values 1/3/6).

I have an N52 MSV80, so can't tell you exactly WHICH of the "Measured Values Blocks" the Fuel Pressure Data is in. It SHOULD be MWB 1, MWB 3, or MWB 6.

To QUICKLY read Fault Codes in ALL Modules, use this Menu Path:
INPA > Functional Jobs > F4 Error Memory > F1 Read Error Memory (All Modules).

See the attached pdf: "INPA Tutorial Quickstart" for HOW to view Functional Jobs Error Memory, Sample ScreenPrints from 328xi, and HOW to save & post ScreenPrints of the INPA Screens you want to save. If you will post the requested ScreenPrints, we can suggest "Next Steps".
George

[gbalthrop]

Attached are ISTA ScreenPrints of wiring diagram, component ID, & Lines ID, for 2008 MSD80 LP & HP/Rail Sensors,
per prior post.
George

[taylorchuck]

Ill see what info I can get when I get over to the car again. I can tell you that after having the CAS replaced with the FRM, that I was still getting a code present in both. Which makes me wonder what all the shop actually did while they had it. I went ahead and checked out the EKPS function and Im not sure what I found out from the tests. The diagnostic tool I used can activate certain system, and when I test both LPFP and HPFP function I get nothing, and when I test the pressure regulator function I can hear it start up. Does any of this point to the EKPS? When I get in the car I can hear the LPFP kick on, but when I test the function through the EKPS nothing happens.

[taylorchuck]

Problem solved. While I was checking on some things in the car today, I thought Id try to put power directly to the LPFP and see if my MHD data log would show the low pressure increase. When it didnt show an increase in pressure, I checked to make sure all the fuel lines in the tank were connected properly and none were broken. When I checked the sending unit, the line I had previously reattached to its proper place had come apart again. I fashioned up a way to hold the fuel hose in place, checked the low pressure on MHD again and watched it go from .7 to 72 quickly. Immediately after it started and ran. Ive ordered a new sending unit, and as happy as I am to have it working again, Im a little pissed about paying $2000 for some modules I dont think I even needed. How did the shop not see this hose that wasnt even connected? How did they charge me for a diagnosis if they didnt diagnose the problem? Im very upset about that but Ill call tomorrow and hash it out with them. For now, I have my car running, and will remember to always recheck those little things cuz most of the time they end up being big things.

[gbalthrop]

Originally Posted by taylorchuck

Problem solved... When I checked the sending unit, the line I had previously reattached to its proper place had come apart again. I fashioned up a way to hold the fuel hose in place, checked the low pressure on MHD again and watched it go from .7 to 72 quickly. Immediately after it started and ran...

LIVE DATA seldom lies, and OFTEN is best diagnosis (coupled with Pump activation/ "Hot-wiring).

If you talk to shop about the history, you might ask them if they even TRIED to use "Live Data" (LP Sensor signal) to diagnose issue.
George

[lowrydr310]

Which line was disconnected?


Glad you got it fixed. I too had fuel pressure issues that I finally solved by replacing the low pressure sensor. I wouldn't consider it a waste to replace my pump and regulator since they were both cracked with fuel leaking out of the top hat of the pump when the tank was full. Soingaree with diagnosing using data, but in some cases like mine the data from the bad sensor lied indicating a different value than what was really there. I could have confirmed a bad sensor by measuring the actual pressure at the inlet to the HP pump, but since there's no Schrader valve on the N54 id have to rig something inline.

[taylorchuck]

George you are 100% correct. This is the 2nd time this year that Ive been able to figure out the problem with my car with your advice, so once again I thank you sir.

lowrydr the hose that came off is on the sending unit, driver side of the tank. Theres 3 hoses, one has a fitting that connects directly to the pump, the other 2 hoses dont have a fitting and both are mounted to the outside of the pump, but dont connect to a fitting or nipple. The hose that goes to the pump has a plastic Y on the other end. The hose came apart at the plastic Y, so it was just pumping gas around the tank and nothing was going through the filter to the HPFP.