Owned my car for well over a year now and the engine has been flawless except for 2 startups. the most recent was last night. Started the car after being off for 2 or 3 days. Drove less than 5 min up the street and shut off. Did some shopping and returned to the car about 30 min later. The car turned over fine but I had to keep the key turned for 5 or 6 seconds as the engine slowly sputtered to life. Once it has started everything was fine. I decided not to drive to my friend's house and returned home, (again less than 5 min). I shut off the car and waited about 30 seconds and started it up again without issue. I then shut it off and went inside.
As I said, this is the second time this has happened. The previous time was just like the first, a very isolated incident. I do not remember the driving times when it first happened.
I have the very same issue (long crank times), but generally only when the motor is hot and has sat for 15-20 minutes or longer. My mechanic thinks the injectors might be leaking a little at the orfice in the cylinder head, thus needing a few extra cranks to build the correct pressure. I don't seem to have the issue when the motor is cold however....it always starts right up.
Thoughts anyone ?
Don't do short trips in your M is what springs to my mind. Your cars could be gassing up if you are doing short trips under 3k rpm. Nix, do you notice a bit of black smoke after the prelonged start up, does it smell rich ala Zippo Lighter ?
Could be a number of things that are possible causes, duff HT leads / cap, injectors, as mentioned, fuel Pump - amazing the symptoms a weak one can cause., water temp sensor might be playing up. I would keep an eye, ear and nose on things and see if the problem develops but it could just be that the motor needs a good airing. Or.......
I suggest you get Faz to fly over @ 1usd per mile plus expences for his stay at the Fairmont, steaks @ Hy's etc, and hopefully he can get it sorted for you.
Cheers.
Well i dont know if this covers the M5, but it has helped on other E34 5 series.
When the car is coold and the ignition key is turned on position 2(Lights in IC goes on), the fuel pump starts to build up pressure (You hear the pump)
When the car is a bit warmed up, the fuel pump dossent start before you actually starts the engine.
Now if you have a faulty return valve on the feeding pipe (Sits by the fuel pump), then the pressure in the system from the pump all the way up to and including the Fuel Rail, will drop to 0bars/psi
Since the pump dossent start before you start the engine, it can take a little ekstra time bulding up pressure, therefore the loong start time.
Replacing the fuel pump return valve has solved this problem on many bimmers over at bimmers.no (A norwegian site), so this might very well be the same problem on the M5.
I dont really know the English name for the Return valve I'm talking about, but it's a valve that fuel only can pass through one way, and not the other, if it's working 100%
If it fails, the fuel(The pressure) can then run back in the fuel tank, leaving the system without pressure.
I have seen that non return valve fail on lots of times on older S38 and M30 it is one of these faults once you diagnose it on one car it is easily noticed on others - didn't stop my service manager billing £100s to customer for my 30 mins fix!
Nice tip re the non return valve, never heard of that before. I replaced a fuel pump last year and I wish I had know about that valve.
Mr Kerr, what part of our nation are you in ?? Have you seen the stuff about the Edinburgh meet on the 25th, more than welcome if you can make it.
Cheers.
Is the meet still at the Rutland? is that the one behind Bug king or at the bottom of Lothian road?
I will try and make it but my M5 is still in bits, too much work for other people it's hard to turn down money..,,,
Cheers
Stuart
Awright Stuart, yes it is and that would be at the bottom of Lothian Road, next to Caledonian Hilton, Berkley Casino, etc, etc. Easy parking @ Rutland Square, Melville Street, Castle Terrace........
Can you make it ?? I'll be posting final plan on the Edinburgh Meet Thread as soon as I know if our visitors are dining......
Cheers.
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