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M5 Won't fire up

3K views 13 replies 3 participants last post by  B767capt 
#1 ·
So the first cold morning´s hit here in Finland, -6c today. Fired up my car at noon and it runs for a ten secs and stalled right away, and won't start anymore. SMG pump primes and gears can be selected normally, fuel pump was ok, tried to jump it with another car since the battery voltage got low when I tried to crank it for a while. Any suggestions? :confused::confused::confused::confused:
 
#7 ·
So could it be that both of them have gone bad? Had rough idle at cold starts before, and it actually stalled on me and went from there complete blackout. I try to get to the TB's today, can I start the car once my intake and other stuff are out??
 
#8 ·
It is unlikely that both sensors went bad. Perhaps a common line between them that failed. They share a 5V reference signal. Are the harnesses in gods shape? And fuses blown? There are 2 30A fuses associated with the TAs.

No, you should not start your car with the intakes off. The MAF see no flow and the oil feature and vacuum are disconnected. Bad news. It might start, but it will throw a million faults. And you run the risk of taking in debris.

Instead run the rheingold TA test. That will assure the setup works properly.
 
#9 · (Edited)
Ok, thanks for reply. TA's are fine, everything moves a bit when ignition is turned on. Seem's like problem in fuel feed now. I opened fuel line from the front and no fuel came out from it, it's all dry, no fuel pressure at all at the front or back. Tank is full but nothing. Any ideas what I should look up next?
 
#10 · (Edited)
Okay. TA fine. But you still have a (new) code related to the Hall sensors. Or did you forget to clear the codes? If the code returns after you clear them, you may have an issue you probably should not ignore. The fact they move a bit at startup does not equal they are perfectly fine.

No fuel pressure? That must be the pump or a severely clogged filter (unlikely that it is that bad). Make sure the fuse to the pump is not blown first before you start replacing the filter and/or pump. And to be ABSOLUTELY sure that it is the pump and not a leaking injector, if you prime the pump the pressure is still zero, correct? Or does the pressure build and then slowly droop down?
 
#11 · (Edited)
Okay. TA fine. But you still have a (new) code related to the Hall sensors. Or did you forget to clear the codes? If the code returns after you clear them, you may have an issue you probably should not ignore. The fact they move a bit at startup does not equal they are perfectly fine.

No fuel pressure? That must be the pump or a severely clogged filter (unlikely that it is that bad). Make sure the fuse to the pump is not blown first.
Will get back to those codes later on. Now this is what we found just, there's something broken on fuel filter connections. Fuses are ok, and pump it self makes noises.
 
#14 ·
From what I remember, the new part number doesn't include the level sensor so you'll have to use the old one. Disconnect the fuel line from the fuel rail in the engine bay and then attach a hose to the fuel line so you can flush a gallon through into a catch can after you install the new filter by turning the ignition on. I'd check for leak down afterwards if I were you if you have a pressure gauge.
 
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