Starter or fuel pump problem?

[Nemo]

I’m new to this site. I joined because I can’t find any answers for my 2001 Z3 issue. I hope someone can come to my rescue.
For the last 10 weeks, approximately once a week my Z won’t turn over to start. Within a minute or two, on the second or third attempt, it starts. I tried turning the key to the AC position for 3 seconds prior to starting, but it still won’t start at times. (A mechanic said this would help to diagnose the issue.) The battery is fine.
Now, just two weeks ago my Z started stalling. It’s stalled on three occasions. Once while idling and twice while going about 5mph. Afterwards, it started again on the first or second try. Once the idle was rough for 3 to 5 seconds.
The dealer says they have to “catch” it when it’s not starting. Really? Even if it doesn’t start, on the next try it probably will. I simply don’t understand why a scan can’t lead us to a solutions? Any suggestions? What are the possible solutions. I think the dealer will start fishing soon and I have no clue.

 

[ExMX5owner]

Gidday Nemo. First Ill move your post to right place to post it and a helpful reply is more likely, and welcome to the forum. Everyone is going to tell you to get your own code reader, so that you are not guessing at it. They are worth their weight in gold seriously, if the fault is not immediately evident by the codes thrown the reader will eliminate faults that are not... And update your profile, so we know where you are, Its helpful as this is a global forum and others that may be locals may help... .

I had a similar set of symptoms a couple of years back, turned out to be 2 things, vacuum leak & Cam angle sensors, As soon as I could see the codes, The members here helped immensely, In that my Z had more than one issue, as I suspect yours does...

 

[AntStark]

I agree with @ExMX5owner it sounds like the cam position sensor is bad.

 

[Mike Fishwick]

If the engine does not turn over sometimes, I think you can rule out clever things such as the cam sensor etc. For the same reason it is also very doubtful if a code reader would be of any use. they are not a panacea for all ills! A code reader may be useful for your stalling problem, but fault diagnosis should start with the simple things, such as checking for splits in the rubber induction bellows between the airflow sensor and the throttle body. An air leak here will prompt a code reader to give an ambiguous message of 'Lambda Voltage Implausable,' which has caused many people to spend £100 each on a pair of new probes - only to find no difference!

On the cam sensor front, I always pull out my exhaust cam sensor at every oil change, and wipe off the accumulation of tiny metallic particles from the probe as a simple preventative measure. The inlet sensor requires removal of the VANOS inlet solenoid, so s a little more involved - I have only done this once.

Your cranking problem sounds like a voltage drop, which could be caused by a lot of factors, from a high resistance battery cell to poor connections. It may even be related to your stalling problem - but do not look for a 'Silver Bullet' which will cure all problems. Stalling is often caused by a sticky idle control valve or induction air leaks, but look for one fault at a time.

Buy yourself a voltmeter, preferably an analogue type, as these are preferable to digitals when looking for transient problems. Look at the basic things, such as making sure that the battery is in good condition, with clean tight terminals on the battery and the starter motor. Do not forget the earth connection.

Then measure the battery voltage while the engine is running - you should see between 13,5 and 14 volts or so - and with the engine stopped for a while. Also check at the battery terminals, while someone else tries to start the engine. Then repeat the test on the actual battery cables. If this is OK do the same thing at the starter motor contactor terminals.

If in doubt, use a jump lead between the jump start terminal in the engine bay and the starter contactor, and make sure that you can hear the contactor operate, and that the starter motor does not run without engaging with the flywheel. Starter contactors can be damaged by low battery voltage reducing the pressure between their contacts, and therefore causing arcing and burning of the contact surfaces.

If nothing else, you will learn a lot!

 

[the Nefyn cat]

A mechanic said this would help to diagnose the issue

Never heard that one before, but there again I've only been a mechanic since the early 70s, what would I know? Always a code reader, and letting us know (roughly) where you are may help. We're all over the place, and many have readers of their own.

 

[t-tony]

Sounds like same symptoms my Z3 had when the inlet cam sensor was failing. But best to use a code reader to be honest.

Tony.

 

[Nemo]

Gidday Nemo. First Ill move your post to right place to post it and a helpful reply is more likely, and welcome to the forum. Everyone is going to tell you to get your own code reader, so that you are not guessing at it. They are worth their weight in gold seriously, if the fault is not immediately evident by the codes thrown the reader will eliminate faults that are not... And update your profile, so we know where you are, Its helpful as this is a global forum and others that may be locals may help... .

I had a similar set of symptoms a couple of years back, turned out to be 2 things, vacuum leak & Cam angle sensors, As soon as I could see the codes, The members here helped immensely, In that my Z had more than one issue, as I suspect yours does...

Thank you!! I’ll take your suggestions.

 

[Nemo]

If the engine does not turn over sometimes, I think you can rule out clever things such as the cam sensor etc. For the same reason it is also very doubtful if a code reader would be of any use. they are not a panacea for all ills! A code reader may be useful for your stalling problem, but fault diagnosis should start with the simple things, such as checking for splits in the rubber induction bellows between the airflow sensor and the throttle body. An air leak here will prompt a code reader to give an ambiguous message of 'Lambda Voltage Implausable,' which has caused many people to spend £100 each on a pair of new probes - only to find no difference!

On the cam sensor front, I always pull out my exhaust cam sensor at every oil change, and wipe off the accumulation of tiny metallic particles from the probe as a simple preventative measure. The inlet sensor requires removal of the VANOS inlet solenoid, so s a little more involved - I have only done this once.

Your cranking problem sounds like a voltage drop, which could be caused by a lot of factors, from a high resistance battery cell to poor connections. It may even be related to your stalling problem - but do not look for a 'Silver Bullet' which will cure all problems. Stalling is often caused by a sticky idle control valve or induction air leaks, but look for one fault at a time.

Buy yourself a voltmeter, preferably an analogue type, as these are preferable to digitals when looking for transient problems. Look at the basic things, such as making sure that the battery is in good condition, with clean tight terminals on the battery and the starter motor. Do not forget the earth connection.

Then measure the battery voltage while the engine is running - you should see between 13,5 and 14 volts or so - and with the engine stopped for a while. Also check at the battery terminals, while someone else tries to start the engine. Then repeat the test on the actual battery cables. If this is OK do the same thing at the starter motor contactor terminals.

If in doubt, use a jump lead between the jump start terminal in the engine bay and the starter contactor, and make sure that you can hear the contactor operate, and that the starter motor does not run without engaging with the flywheel. Starter contactors can be damaged by low battery voltage reducing the pressure between their contacts, and therefore causing arcing and burning of the contact surfaces.

If nothing else, you will learn a lot!

Excellent advice. I’ll take all I can get. Thank you!

 

[Nemo]

Sounds like same symptoms my Z3 had when the inlet cam sensor was failing. But best to use a code reader to be honest.

Tony.

Thanks for the information.

 

[t-tony]

By the same token, if you have a split in an induction hose it won't magically reseal itself now and again. A split is there all the time. That IS what happened on my Z3 regardless of Mr. Fishwicks opinion.

Tony.

 

[Mike Fishwick]

OK Tony - that is what happened on your car, but you seem to be jumping to the conclusion that no air leak can be intermittent. Things are not always how you think they should be, and I have seen a few intermittent induction system air leaks in my time . . . By the way - from the tone of your reply perhaps I have managed to upset you in a past life?

 

[IainP]

I’m new to this site. I joined because I can’t find any answers for my 2001 Z3 issue. I hope someone can come to my rescue.
For the last 10 weeks, approximately once a week my Z won’t turn over to start. Within a minute or two, on the second or third attempt, it starts. I tried turning the key to the AC position for 3 seconds prior to starting, but it still won’t start at times. (A mechanic said this would help to diagnose the issue.) The battery is fine.
Now, just two weeks ago my Z started stalling. It’s stalled on three occasions. Once while idling and twice while going about 5mph. Afterwards, it started again on the first or second try. Once the idle was rough for 3 to 5 seconds.
The dealer says they have to “catch” it when it’s not starting. Really? Even if it doesn’t start, on the next try it probably will. I simply don’t understand why a scan can’t lead us to a solutions? Any suggestions? What are the possible solutions. I think the dealer will start fishing soon and I have no clue.

Having had exactly the same problems on several E36's I expect you have more than one problem.

Starter
Likely a poor connection either at the battery, but more usually at the starter, I'd clean the terminals if it were mine. First thing i did on mine, job to do on my son's car this weekend.

Stalling
Vacuum leaks are likely on 20 year old rubber, there's quite a lot of it. Also a rubber hose to the fuel pressure regulator on the M43/44 engines that can crack, split or go porous. That causes lumpy idle and stalling, as will vacuum leaks.
Cam position sensor on it's way out does cause intermittent stalling issues.

As pointed out, a decent scanner will tell you straight away, any stored fault codes, fluctuating fuel trims, etc. Not expensive either.

Put you location in your profile, as the Nefyn cat points out, lots of us have our own scanners, some more sophisticated than the basic ones the Z3 needs.

 

[Nemo]

Having had exactly the same problems on several E36's I expect you have more than one problem.

Starter
Likely a poor connection either at the battery, but more usually at the starter, I'd clean the terminals if it were mine. First thing i did on mine, job to do on my son's car this weekend.

Stalling
Vacuum leaks are likely on 20 year old rubber, there's quite a lot of it. Also a rubber hose to the fuel pressure regulator on the M43/44 engines that can crack, split or go porous. That causes lumpy idle and stalling, as will vacuum leaks.
Cam position sensor on it's way out does cause intermittent stalling issues.

As pointed out, a decent scanner will tell you straight away, any stored fault codes, fluctuating fuel trims, etc. Not expensive either.

Put you location in your profile, as the Nefyn cat points out, lots of us have our own scanners, some more sophisticated than the basic ones the Z3 needs.

I appreciate it. Sounds like I have a lot to consider.