wont start first time, always starts second

StevoL · Nov 27, 2012

have had a weird issue for a while now where 80% of the time the car doesn't start first time, but it will always start second time

no error codes, the only other problems I can think of is a non working cruise control which im also unsure of and what seems like standard bad vanos rattle

Ive replaced the fuel filter, pressure regulator, vacuum hose and it has a fairly new battery

any ideas?

youngcw334 · Nov 27, 2012

I had this issue and it turned out to be my starter. I think it is somewhat of a common issue for our cars. Pretty easy diy and not too expensive of a part.

gzig5 · Nov 27, 2012

If it is cranking over, its not the starter.

I have the same issue though more intermittent as do several others. Do a search for their posts. It will crank and crank but doesn't seem to want to fire on the first try. Second try it fires immediately. My understanding is there could be several sources including:
contact issue in the key mechanism which doesn't enable the spark firing.
fuel pressure bleed down due to leaking injector, pressure regulator, or fuel pump.
something in the DME not being satisfied to provide spark (whatever that may be)

I think mine is fuel pressure related. I replaced the pump and the rate of occurrence has decreased. I also find that if I hop in and hit the starter it is more likely to not fire, but if I turn the key to position 2 and wait two or three "dings" it starts just about every time. Turning the key on activates the fuel pump and allows the pressure to build properly at the injectors if it has bled down. Let us know what you find out.

M5_MONSTER · Nov 27, 2012

I had this with mine, it was the fuel pump. I have also seen this on a couple of other e39 m5s and also it turned out to be the fuel pump.

bimmerule · Nov 27, 2012

Your fuel pump's days are numbered.

gzig5 · Nov 27, 2012

I should add that the fuel pump relay could be another suspect. I did not change mine yet. First did the Aeromotive pump install to see how that works out and so far it has been about 95%.

68FB · Nov 28, 2012

If you turn the key to the # 2 position (just before crank position) and leave it there for a few seconds, and then crank, does it start?

StevoL · Nov 28, 2012

no, thats what I do everytime

it always seems to have no problem cranking so ive always leaned to it being some sort of fuel supply issue, on the second go it instantly starts etc

I should have mentioned that its only when left overnight or longer when the issue occurs, its never a problem if I stop somewhere for a few hours, it will always start then...

gzig5 · Nov 28, 2012

That is exactly the same symptoms I've had. Overnight or sometimes after 8-9 hours at work. If you want to confirm it is the fuel pressure you could rig a pressure gauge to the Schrader valve on the pressure regulator and have it come up under the hood and check it before you start. I think when I asked, I was told there is a check valve in the pump and that could be letting the pressure bleed down. If you still have the original filter and pump it is not a bad idea to replace them as a preventative measure if you have 70,000+ miles.

StevoL · Nov 28, 2012

already replaced filter, will put in a new pump and see how it goes, car has done 100k+miles probably on the original so it seems a good time to do it anyway

interesting that you still get the issue sometimes even after replacing it however, seems like theres something else contributing

ill update with results

gzig5 · Nov 28, 2012

I think it has only happened twice in the two months or so since I did the pump. Both times I was in a hurry and didn't wait with the key in position two. Prior to the pump it would do it several times a week even with the proper wait before cranking. So, I probably still have a pressure let down somewhere but not near as bad as it once was. I'll throw a pressure gauge on it if I feel so inclined, but the next maintenance move is probably to have the injectors cleaned and flowed.

M5_MONSTER · Nov 28, 2012

<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w

unctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w

ontGrowAutofit/> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif]--> Mine was the same, if i left it overnight or for a long period, it would do it, but if it was warm, or only left for a few hours, it always started absolutely fine. Leaving it on key position 2 to purge the pump, also didn’t solve the problem. I changed fuel filter, injectors, regulator, and quite a few other things to no avail, and finally the pump solved the issue.

tradin1 · Nov 28, 2012

rent the fuel pressure gauge from autozone and see where your pressure is in the morning.

-R

MasaK · Nov 28, 2012

I had similar problems on another car, there the problem was dirty crankshaft position sensor.

StevoL · Nov 28, 2012

would a crankshaft position sensor throw codes or have any other symptoms?

im in australia theres no autozone here, couldnt find anything with a quick search online where I could rent a pressure gauge somewhere near me, ill buy one if i can find one cheap enough otherwise would rather put the $$ into a new pump, what psi range do I need

68FB · Nov 29, 2012

Pressure is 72 psi at idle with vacuum line to the pressure regulator disconnected and 62 with it connected. The Schrader valve on the pressure regulator is the same size/thread as a tire valve. Make sure the gauge comes with an adapter for that.

Leaving the key on for while may not be working because the DME may be shutting the pump down after a couple of seconds if the engine isn't cranked. That's typical for other vehicles but I don't know about the M5.

Soarbank · Mar 3, 2013

Hi all

Did StevoL ever get this resolved?( I can't PM yet).

Mine has been doing this for two years.....:nono: I didn't worry about it too much as I expected the problem to disappear as I worked through replacing all the sensors and other electrical components as part of the 'restoration' of my car. However, the problem remains. This is where I am so far;

Replaced in last 2000 Kim

Inlet and exhaust cam sensors
Crank sensor
Fuel pump
Fuel filter
Pressure regulator
Fuel injectors serviced and leak tested

Replaced in last 5000 Kim
Battery
Ignition electrical switch
Coolant (DME) sensor
Coolant outlet sensor
Oxygen Sensors (pre-cat only) :1:

In last 10,000 Kim
Complete set ignition coils
Spark Plugs
Pair of MAF's

I've got good fuel pressure with the pump priming the fuel system straight to 4 bar before cranking.

The car runs superbly, no hesitation, no misses and no fault codes (except aux air...but that's all of us). Recent dyno run produced 332 RWHP which for 200,000 Kim I thought pretty good. Fuelling across the rev range through the dyno run was perfect. (Well, maybe 1 in ten it'll go first time)

But leave it for 7-8 hours and it will not start 1st time, always second, without exception.

Someone mentioned a starter motor problem - can this be the case even if there are no cranking issues?....Any thoughts and help would be greatly appreciated.

Cheers,

Soarbank · Mar 9, 2013

Soarbank said:
Replaced in last 2000 Kim

Inlet and exhaust cam sensors
Crank sensor
Fuel pump
Fuel filter
Pressure regulator
Fuel injectors serviced and leak tested

Replaced in last 5000 Kim
Battery
Ignition electrical switch
Coolant (DME) sensor
Coolant outlet sensor
Oxygen Sensors (pre-cat only) :1:

In last 10,000 Kim
Complete set ignition coils
Spark Plugs
Pair of MAF's

I've got good fuel pressure with the pump priming the fuel system straight to 4 bar before cranking.

The car runs superbly, no hesitation, no misses and no fault codes (except aux air...but that's all of us). Recent dyno run produced 332 RWHP which for 200,000 Kim I thought pretty good. Fuelling across the rev range through the dyno run was perfect.

But leave it for 7-8 hours and it will not start 1st time, always second, without exception. (Well, maybe 1 in ten it'll go first time)

Cheers,

Hi all, this is the work done to date (post #17). The only missing item in that list is the Vanos solenoid seals done last month.

Cheers

68FB · Mar 3, 2013

Wow, strange all that stuff didn't fix it. For clarification, on that first crank, does it fire at all?

Sailor24 · Mar 3, 2013

+1 very weird those did not fix it. Does your fuel pressure hold at pressure when you shut the car off or does it drop continually? Needs to hold for an hour min. Do you ever smell gas when you first get to the car? Will it start if you crank it for 20 sec or no change?

Soarbank · Mar 3, 2013

Thanks for the replies....

Sometimes it'll try to fire, but never actually start, never. 1 in 10 (ish) times it'll start with no issue and burst into life immediately.

I've never tried cranking for that long, but I'll give it a go and report back.

Fuel smell - I do get a fuel smell occasionally but only when I fill the tank to the brim. My garage is part of the house so I make a point of only ever filling to about 80% full now and that seems to prevent gas fumes.

AND I did do a pressure hold test - the fuel pressure dropped to zero in 20 minutes. BUT I put this down to the gauge itself as it had a bleed line which leaked a SMALL amount of fuel. However, once the key was turned to pos II, fuel pressure went straight to 4 bar and registered 4.5 bar during cranking.

Are we thinking fuel?

Cheers,

68FB · Mar 4, 2013

Soarbank said:
Sometimes it'll try to fire, but never actually start, never. 1 in 10 (ish) times it'll start with no issue and burst into life immediately.

So you are getting spark and some fuel. I think that rules out one suspicion I had, that the DME was seeing something it didn't like on the first crank and cutting spark and fuel, or not seeing something it needed to see.

It does sound like fuel. To confirm you are getting good spark you could pull a coil, plug in one of those spark checkers with the adjustable gap set at 1/8" and crank.

Soarbank said:
AND I did do a pressure hold test - the fuel pressure dropped to zero in 20 minutes. BUT I put this down to the gauge itself as it had a bleed line which leaked a SMALL amount of fuel. However, once the key was turned to pos II, fuel pressure went straight to 4 bar and registered 4.5 bar during cranking.

For clarification, you had 4.5 bar during the crank but no start?

And do you have any codes?

Sailor24 · Mar 3, 2013

Even though you have replaced everything that is supposed to hold the pressure you could have a very small leak somewhere else. Like a line or something. Is the pump OEM or aftermarket? Even overfilling the car should not give you a fuel smell, the system is sealed. Any other codes? I might fix my fuel pressure gauge and try the test again.

Soarbank · Mar 3, 2013

After thinking about where the replies were heading I just did a quick test....

I bridged the fuel pump and let it run for 15 seconds or so, then, with it still bridged and running I tried to start the car...no go first time, perfect start second time.

I'll try the extended cranking suggestion tomorrow....that's the fun with this problem, you have to wait 7-8 hours to repeat any experiments and tests....

Cheers

Sailor24 · Mar 3, 2013

There was another thread in the past year or two that was like yours and it was not fuel related but something strange. Just can't find it in any of my searches so far.

Soarbank · Mar 3, 2013

Thanks Sailor, greatly appreciate your help.

Cheers

Soarbank · Mar 3, 2013

The new fuel pump is genuine. I have had the car on my hoist a couple of times to look for a fuel leak, nothing obvious or immediately apparent. There was no sign of a fuel leak under the plenum either (when I had the injectors out). At that stage I would have bet money on it being a leaky injector but this was ruled out a couple of weeks ago when the injectors held 6 bar on a test bench.

I'll pull the rear right wheel liner out on the weekend and start or look for the less obvious fuel leaks.

Cheers

Sailor24 · Mar 4, 2013

Easier than that hook up the fuel pressure gauge and watch for it to start falling. Then pinch a line and see if it stops if it does not chose a different one. One of the three will likely stop it. You must do this cold because if the engine is warm the fuel in the engine compartment heats and expands which raises the pressure. That same thing I believe is what causes the strange start behavior. Once all the pressure is gone when the fuel cools a small vacuum is formed, I don't think the pintle will resist that force.

Soarbank · Mar 4, 2013

Sailor24 said:
.....cold because if the engine is warm the fuel in the engine compartment heats and expands which raises the pressure. That same thing I believe is what causes the strange start behavior. Once all the pressure is gone when the fuel cools a small vacuum is formed, I don't think the pintle will resist that force.

Sailor, I've been thinking about this since you posted it.......if there's air in the system and it is pushed to the injectors when I first try and start the car then that would (to me) explain the behaviour - the first attempt to start the car simply bleeds the fuel system of air, ready for the [always successful] second attempt.

My question is then, can the the fuel system in this state of vacuum (from cooling) suck air into the fuel lines without an apparent fuel leak?

This is the greatest amount of progress I've made on this issue for at least a year - thank you all so much.

Cheers,

Soarbank · Mar 4, 2013

Yep, 4.5 bar of fuel pressure whilst cranking. No codes. I'll check for spark as I admit that I have not previously done this.

I neglected to mention in my first post that I have replaced the DME relay and fuel pump relay. I have NOT, however, replaced K6326 'unloader relay' in fact I've not even looked at this one.

Looks like my next jobs are;

1. Check for Spark
2. Look again at fuel pressure when engine is shut down and left
3. Check for codes

Cheers,

M5convert · Mar 4, 2013

I did some searches for BMWs with starting on the second try, and one guy solved his problem by changing his fuel filter and MAFs.

Soarbank · Mar 5, 2013

Thanks convert, that's why I didn't give the problem any attention early on as I knew I'd be replacing all those components. I'm here now as I've replaced nearly all 'service' items yet the problem persists. My first post lists the work done so far.

Thanks

Sailor24 · Mar 4, 2013

Unloader relay causes different problems not yours.

Soarbank · Mar 4, 2013

Good, that's that one eliminated.

Cheers

wont start first time, always starts second

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