Would appreciate insight on my cold start issue

[RenaissanceMan]

2005 X5 3.0 w/211k miles. Started having cold start issues about a week ago. First start attempt of the day when temp was under 45 or so degrees would result in just cranking with no start. Would take between 2 and 5 start attempts for it to finally fire up. Did a bunch of thread searching here and went through the usual checks. Wasn't getting any error codes via INPA, fuel pressure looked to be normal, and it otherwise ran perfectly once started. Subsequent starts during the day had no problems. EDIT: Starter turns every time. Fuel pressure is normal while running but I haven’t checked fuel pressure yet with the fuel pump relay removed and jumpered with the car not running.

Anyways, last weekend it wouldn't start again so I pulled the fuse/relay panel. After removing and cleaning/reseating the fuel pump relay, it started immediately and for the next 4 days I didn't have the issue again. However, problem reappeared this morning and it took 2 tries to get it to start.

I had assumed the relay was just making a poor connection in the colder weather and that was the problem, but apparently that's not the case. Questions:

- Do relays like this sometimes behave intermittently when they are starting to die? Or do they just die all at once?

- Is it safe to assume that camshaft position and crankshaft position sensors will throw codes when they malfunction?

- Have any of you ever experienced a bad pressure regulator on the filter causing intermittent issues like this when the vehicle is cold?

Thanks in advance for the help!!!

[BimmerBreaker]

If fuel pressure was normal, I don't know why the condition would be altered by re-seating the fuel pump relay. Maybe you need to verify if fuel pressure was in fact normal or not, but if it runs fine when driving - I don't think this is the issue. Those have an EKP relay and do not behave, or fail, like normal relays.

Camshaft position sensors will throw codes but will not prevent the engine from starting. Crankshaft position sensors will usually throw codes, but not always. If the crankshaft sensor is faulty, you will not have any tach signal when cranking.

I have never heard of a failing fuel pressure regulator causing issues only during cold starts. But again, if fuel pressure is ok, I don't know why this is a main consideration.



If fuel pressure is in fact OK as you say then you are going down the wrong path looking at fuel system related stuff.
Double check if fuel pressure since you dont sound confident in that but if is actually ok but if it is, look elsewhere. I start with the simple stuff in cases like this - make sure the battery connections are tight, engine ground strap secure, etc. Could also simply be a starter on it's way out - when those fail, they do often fail intermittently.

[X5chemist]

Mine had a similar issue. Hot or cold. Sometimes it would take 2 cranks. Super rare for 3 cranks. I did a lot of work on mine though. I think a starter replacement helped the most. A new starter spins up the 3.0 fast. Check the condition of the battery too.

[RenaissanceMan]

Thanks for the replies so far. Just to be clear, I don’t have a starter issue. Starter turns every time. Fuel pressure is normal while running but I haven’t checked fuel pressure yet with the fuel pump relay removed and jumpered with the car not running.


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[80stech]

Check the pressure properly (stopped, running and hopefully not starting) before you do anything with the relay. For sure the fuel pump relay could be intermittent. You could try cycling the key to activate the fuel pump an extra time or two before trying to start (leave on for a few seconds to prime the fuel system) to see what that does as well.

[getty150]

I've had this concern for years with me m54. The car would start sometimes in an instant and others at the regular 2 starter turns. And on the 8th crank it would take 5 to 6 turns of the starter. I can't tell you the various parts I've replaced in order to achieve the instant start or the short spin of the starter!
To make a long story short, I'm recently finding/discovering that I don't know the Car Battery and it's various specs. I thought all I needed to know was Cold Cranking Amps=CCA.
or the size needed group #49.

Your problem (our problem) is the battery...it's age, it's size, it's CCA, it's RC, it's Amps per hour and mostly the type...lead flooded or the costly popular mighty AGM. And most importantly the amount of attention/charging we give to our existing batteries!
Did you know we BMW owners need to have the battery charged at least once a week at the end of the week if car is used throughout the week? These cars are pigs at consuming power.
Power seats
Power windows
Power breaks

And so on...you get the picture.
Can the Alternator keep up?

Here's my findings...
Lucky you!
I'm really proud of the participation and information given here...I learned a lot!
https://r.tapatalk.com/shareLink/top...ink_source=app

[Effduration]

try unplugging the MAF on a cold morning. cold start...and see if its any better.

I am wondering if you have a big vac leak somewhere...

[andrewwynn]

I had very similar symptoms on wife's m54 e53.

In our case was an o-ring between the FPR and fuel filler.

If/when you can get it to start watch the fuel pressure the needle should be absolutely still at idle. Hers wiggled about 2 psi.

The other main feedback/test was it no longer held pressure when off (o-ring leaking pressure back to the tank return line).

Before fix pressure would drop from 50 to 45 at key off and within 15 minutes drop to maybe 10.

After the fix, pressure would be ≈ 30 psi overnight.

The last cold start before replacing the fuel filter took about 10 tries of 6-7 seconds cranking before it finally fired up.



The tiny o-ring was the fault. I replaced the whole filter/FPR assembly because it was a reasonable $65.







I did measure the o-rings for future reference since we had two 2001 at the time and i was used to cloning repairs.

Measure your fuel pressure at idle looking for needle shake and then leave off for a few hours it should still have 20-30 psi even after overnight.

I never figured out why the ≈2 psi jiggle caused such a fuss but some days it would take more than a few tried to start never had a long crank again after replacing the FPR.

[RenaissanceMan]

Hey everyone thanks for the replies. Wanted to give an update.

Did some more testing on fuel pressure. Removed the relay and jumpered with the X5 off and not running and measured pressure. Looked spot on at 50psi. With the X5 running, also looks spot on at 40psi with no 'needle shake' as @andrewwynn described. Fuel pressure holds steady with the X5 off and not running after sitting a long time. So from that looks like fuel pump and fuel pressure regulator in the filter are operating properly.

How did I get it started? Once again, just simply removing and reinstalling the relay resulted in the X5 starting up immediately. At this point I feel like I have a fuel pump relay that is working intermittently when it's cold outside. Going to replace that today with a brand spankin' new one and report back on the cold start results.

[andrewwynn]

My e3 was 0psi. You're m4 engine, correct?