[gherardini]

History.... 2003. E39. Stock. Changed plugs, fuel filter, air filter, MAFs and oil/filter. [OK, not in the same day, it took a bit] 80k miles, running well and not throwing codes.

However, on cold starts, she cranks for a bit, maybe 10 - 15 seconds. Then she'll catch, begins firing slowly for a couple seconds, then idles perfectly and has no performance issues. Does not choke off at red lights, runs very well. Stop, run in for an errand, come out and start her and she'll start fine, *maybe* a very slight, almost imperceptible delay while cranking, but if she's been sitting for a while, I get the delayed start.

- Thought it might have been the MAF, changed it.
- Crank position sensor?
- Fuel pressure seems fine, hit the release valve on the fuel rail, fuel went shooting out. We tried turning the key on, waiting a few seconds, turning it off, then turning it on again, waiting a few seconds then starting. It seemed to help a while ago, but now not so much.

Anything else I should look at?

Thanks!

 

[gherardini]

Anyone have any ideas??

 

[Sailor24]

Does it have a long crank on a hot start?

 

[gherardini]

no. but i might say that it cranks for a second too long. it should start instantly, but goes for maybe a second.

cold starts, however, can take 10 - 15 seconds of cranking, and sputters for 3 - 5 seconds while it catches ignition, then idles perfectly. something is off, just not sure what it is.

 

[Sailor24]

It sounds like one of two things. Either you have a leaky injector or the back flow pressure regulator is letting the pressure back to the tank. Small leak in either case. If it was me ( I have all the tools) I would hook up a pressure gauge at the entrance to the fuel rail, run the car to make things normal. I would note if the fuel pressure fell after the car sat.If the pressure dropped I would presume a leaky injector or leaky outlet of the fuel rail pressure regulator, or the pressure reg that is also a back flow preventer at the tank. The simple thing to do after you decide something is leaking is figure out where.Step one is pinch of a line behind the pressure gauge but close. If the pressure does not fall then the leak is behind it, likely the back flow valve or a line. A line leaking has obvious symptoms mainly smell of gas. That would be the part in the fuel tank.

If the pressure dropped then it must be an injector or the pressure reg is letting fuel flow to the return line. next test would be to pinch off the return line (after the rail) and wait to see if the pressure drops. No drop then it is the pressure reg.

You don't likely have that pressure gauge that I have, so you will have to do it the" I think it behaved different" way. Pinch off the return line first and let the car sit. Remove the pincher and start the car, does it behave different? Test two pinch the line going to the fuel rail as close to it as possible and let the car sit. release before start is that different? Last test pinch as close to the tank as you can test as above.
How do I pinch you ask? on a rubber line only with vise grips and two sticks to protect the line. You could buy a line clamp which is the right tool for the job, or a small "C " clamp would work. Just don't damage the line.

All that said my best guess is a leaky injector. I say that because of your post. If the pressure is dropping because the fuel is getting back to the tank, then you have an extended crank but then a normal start. You have a slow start like one cylinder is flooded.For that I would buy Lucas injector cleaner and add double or triple dose in the first tank and use it till the bottle is empty at the recommended rate. This may work if the injector is dirty but it could be a bad spring or other mechanical fault that would require a new injector.

Hope this helps good luck.

 

[Hasan Shaikh]

I think you need to change your sprk plugs. When was the last time you changed them.

 

[gherardini]

Sailor24, that's a hell of a post. Thank you. I will get on that when I get back from Europe next week.

Hasan, I might agree with you, but plugs were changed this summer. Maybe 7,000 miles ago.

 

[Sailor24]

I hope I can help. I will admit I do not have vast E39 knowledge but I will soon. My new M5 had many issues 12 codes in the engine no DSC and 27 body codes. I have fixed them all, but a thermostat and a park sensor in the two weeks I have owned it.I am giving you this from 20 years of E34 experience. From what I have seen some systems have changed, but like true German engineers they don't change what works. Good luck.

 

[gherardini]

Solved. Fixed. And it only cost me $500 to get it that way... [grumble, grumble, grumble.....]

It looks like Sailor24 was on the right path.... My wife was nagging me to get it fixed.... so I took it to my indy... here's what he did...

- Perform startup flow test
- ck key recognition
- check ignition circuit
- check fuel pump circuit
- check for false air entry engine
- unmetered
- check fuel pressures
- check volume max prime
- found system rest pressure not holding
- replace fuel pump check valve regulator assembly

$350 for the system check, $110 for the regulator.

Somehow I still think it's all related to when I changed out the fuel filter last summer. I must have dorked something up while under the car.... But just to save someone else some of the pain I've experienced in figuring this out.... and extended cranking on start could be a bad fuel pump check valve regulator.

 

[chowdah]

Thanks for the update.

PS - What is this thread doing here? Shouldn't it be either:
E39 5 series Forum - The Unofficial BMW M5 Messageboard (m5board.com)
or
E39 M5 and E52 Z8 Discussion - The Unofficial BMW M5 Messageboard (m5board.com)

 

[Sailor24]

Thanks for the update.

PS - What is this thread doing here? Shouldn't it be either:
E39 5 series Forum - The Unofficial BMW M5 Messageboard (m5board.com)
or
E39 M5 and E52 Z8 Discussion - The Unofficial BMW M5 Messageboard (m5board.com)

Got moved was on the M5 board.

 

[Sailor24]

Was always curious what happened, thanks for the update. This was my first attempt at helping someone on the board. Glad it worked out, sad it cost ya $500 though.