[zou_n@hotmail.com]

Hi there original post is here:
https://www.e90post.com/forums/showthread.php?t=1975017

Brief summary, all this happened when I disconnected fuel pump and tried to get some voltage output measurement from the fuel pump connector (fuel pump control module output) for diagnosing purposes (got another no start e90 recently), then vehicle crank but won't start.

I tried to jump start the vehicle (battery was tested and fine, just want to be 100% sure it is not caused by a weak battery) with fuel pressure gauge today and no good luck.

The video below shows when cranks engine speed only reaches 100 rpm, is this too low? Starter did failed and I replaced the brush only a year ago. Works fine till this happened.

Also I saw fuel pressure did reach 5 bar (I connected the gauge to the Schrader valve on fuel rail) when cranking, but when I stop crank, it drops to 0 immediately, does this mean fuel pressure regulator is bad? I searched online and they say fuel pressure should keep around 5 bar for 15minutes at least, does a bad regulator cause no start?
BTW I replaced the fuel pump assembly 1.5 year ago, it is a DELPHI FG0917 (Premium) from RA...

Thank you very much!

[zou_n@hotmail.com]

I did a little bit research and observed other vehicles and seem like crank engine speed should be 250 rpm minimum, 100 rpm is definitely too low ,maybe the rebuilt starter is worn already (pain of the butt to taking off intake for starter replacement...)? The rotor inside the starter has an uneven part which could eat the brush pretty quick.

But I do have concerns about the fuel pressure regulator, it seems not working properly even it might not the cause of the problem.

Someone left a comment on YouTube saying alternator, is it also a possibility?

Thanks for your suggestion!

[gbalthrop]

Originally Posted by zou_n@hotmail.com

... 100 rpm is definitely too low [My Starter Crank Speed, per INPA Screen is 180 to 200 RPM during ~ 1 second of cranking before it fires. The Tach is NOT an accurate reading of RPM during cranking in that speed range. It basically only tells you if there is a signal received by the DME from the Crank Sensor.] ...

Did you ever get your INPA installation to connect with the EKPS Fuel Pump Module? If it STILL does NOT connect, follow the instructions provided in earlier thread, and ask questions about anything NOT clear. If you get an error message, please save ScreenPrint of that Error Message and post here, WITH indication of WHAT button / Function you pushed to CAUSE error message (what Menu choice).

To see RPM (Drehzahl) during starter cranking, Connect INPA to DME Module and view FIRST Analog screen; here's menu sequence:
INPA > DME (Engine | MSV80 for N52K) > F5 Status > F2 Analog > F1 Measured Values Group 1.
Engine RPM is 2nd Row on Left: "Motor Drehzahl" rpm

Please also refer to attached pdf: "INPA Tutorial Quickstart" for procedure on saving and attaching ScreenPrints here. Then attach ScreenPrint(s) of your CURRENT "INPA > Functional Jobs > F4 Error Memory, ALL Modules" showing current fault codes. We need to basically start over.
George

[zou_n@hotmail.com]

Hello George,

Sorry for taking so long. I got the Inpa partially work, and I was able to activate the pump (Inpa->DME->F6->F1->Group1->F7->F1). I did activated the pump and saw 100 reading with green bar, does this mean pump and pump control module are good?

I also got a error message as attached in the attachment, I just selected yes and can hear pump whining noise. Did a little bit research and sounds like it is related to the com port setting, I will try it later.

Please see attached for snapshot.

But I do have a question regarding to what you suggested:
"INPA > DME (Engine | MSV80 for N52K) > F6 Activations > F1 Activations Group 1 > F7 Activate EKP (Fuel Pump) > F1 On/ F2 Off/ F4 Return to DME Control"

My understanding this is test the fuel pump and control system?
Thanks and have a happy new year!

[PhaseP]

does this mean fuel pressure regulator is bad

Either that (regulator or check valve which is same assembly along with fuel filter) or you have a bad fuel leak in the pressurized system. If latter, you should be able to smell the leaking fuel though.

Don't know if failing pressure regulator can cause no start. When check valve is not working good it does cause long start, I know from mine, but wasn't fully bad.

[zou_n@hotmail.com]

Originally Posted by PhaseP

Either that (regulator or check valve which is same assembly along with fuel filter) or you have a bad fuel leak in the pressurized system. If latter, you should be able to smell the leaking fuel though.

Don't know if failing pressure regulator can cause no start. When check valve is not working good it does cause long start, I know from mine, but wasn't fully bad.

Thank you very much for the info, you mean in the fuel sender assembly(left rear seat)? It was replaced 1.5 years ago with VDO / CONTINENTAL Fuel Sending Unit but it is not a very good brand though.

100 RPM crank speed should related to something else saying starter?

[PhaseP]

Yes, the one under the left seat. I guess it was the one under the left seat, I don't recall well. Under one seat there is the fuel pump, and under the other there is the fuel filter/regulator/check valve assembly.
Again from what I can recall, VDO/Continental was the OEM for that part. I wouldn't call it not good brand.

But it is strange that you don't even get any fire up, since you mentioned when cranking there is fuel pressure.

I don't know about cranking rpm speed and it is hard to tell from video.

From my experience with my car, I had times it was cranking real slow during coldest winter mornings, and it was able to fire up, like barely cranking.

It is always best to trace back last you did. It stopped working when you poked to measure the fuel pump signal. So it would be wiser to focus that area. gbalthrop has been guiding you and giving you good advise in that area.

[PhaseP]

Another thing, in your INPA screenshots in your first thread it says MSV70 on them. You should be selecting MSV80, not MSV70 in INPA. You have 328, it is DME version is MSV80. MSV70 is for 06' 325/330 models.

You may also try to disconnect the batter negative terminal for a minute and then connect and give it another shot. It is a long shot, but easy and free.

[zou_n@hotmail.com]

Thank you for the info, actually I did use 8.0 version and was set to com1, but still saw the error msg(any suggestions about the error msg?), I ignored it and proceed and see pump was actuated with green bar. My understanding is this is to actuate fuel pump for testing purpose, if it runs and I saw a full green bar means pump and control is OK?

Not sure if I got enough fuel pressure with gauge reading while cranking means fuel pump is not the cause of the problem.

I tried to ground the engine (saw George's another post mentioned grounding issue will cause sluggish crank), won't start either. Shall I remove and test the starter?

Thanks.

[zou_n@hotmail.com]

Sorry for taking so long, it turned out the fuel sender is bad, fuel pressure regulator didn't maintain the pressure, a 1.5 years vdo, sign.

But after it starts, the idle is not stable an stall, unplugged the maf sensor runs smoothly, maybe during the diagnose I put the intake box on ground shocked the sensor? Brought a cheap one on ebay didn't work, git a junk yard one didn't work either, new one cost 150+.

[PhaseP]

It is very rarely the MAF sensor, and most probably you have a vacuum leak. The line that goes from the valve cover to the intake is one that gets cracked and leaks air in. The valve cover itself may have a crack, the PCV valve that is on the valve cover may be leaking.
Another thing, you may not have seated the air hose to the air filter box during assembly and you may have a leak there.

When air leaks into the engine past the MAF sensor, it causes problem for the computer to keep correct air to fuel ratio. Since the MAF sensor tells it this much air going in, but in reality more goes in.
When the MAF is unplugged the computer falls back to calculating the air going into the engine from engine RPM and so is able to run smoother. It still won't be very smooth compared to working with the MAF, because engine now doesn't know the exact intake air temperature, which is normally provided by the MAF but that is extra detail.

[zou_n@hotmail.com]

Thank you for the information!

[zou_n@hotmail.com]

You are correct, forgot to connect a hose to MAF Valve...

Originally Posted by PhaseP

It is very rarely the MAF sensor, and most probably you have a vacuum leak. The line that goes from the valve cover to the intake is one that gets cracked and leaks air in. The valve cover itself may have a crack, the PCV valve that is on the valve cover may be leaking.
Another thing, you may not have seated the air hose to the air filter box during assembly and you may have a leak there.

When air leaks into the engine past the MAF sensor, it causes problem for the computer to keep correct air to fuel ratio. Since the MAF sensor tells it this much air going in, but in reality more goes in.
When the MAF is unplugged the computer falls back to calculating the air going into the engine from engine RPM and so is able to run smoother. It still won't be very smooth compared to working with the MAF, because engine now doesn't know the exact intake air temperature, which is normally provided by the MAF but that is extra detail.