X5 sometimes crancks but won't start

Hi there,

I have an X5 3.0i (version E53) with M54 engine.

Recently I noticed a strange behavior: sometimes at a cold start in the morning (in summer even) the engine will not start.
The engine cranks and turns over as normally would but will not start. I can keep cranking it for seconds (longest I did 20 seconds) still the same result.
Leaving the car sit for couple of hours and next time will start at the first key.
I had may mechanic check out the car unfortunately nothing wrong came up (no error code, loose connector, etc.).

So far I couldn't find a pattern of this behavior... however I would say it's happening once out of 20 times.

Dear reader, Thank you in advance for any suggestion you may have.

Regards,

For the benefit of the reader:

Visit to the dealership did not help. After 2 days and over $200 (out of my pocket) for diagnostics the dealer recommended replacing fuel filter ($410) and/or fuel pump ($720) which I declined.
Planning to purchase filter from Amazon.com for $50 and install it myself and fuel pump (if required) for $335.
Will keep u posted

It is very disappointing to see all this human greed and ignorance around us...

How many miles - I can see a fuel filter but not sure about a fuel pump. Yes dealers will knock you out of the park for price! BMW's are not difficult to work on as people think.

Thanks for the replay and thanks for the encouragement

The car has 150K, just bought it about 2 months ago, I am not sure if this a pre-existing issue or not...anyway will try replacing the filter (the pressure regulator is incorporated in it) and will see. Anyway the fuel filter looks old judging from it's exterior appearance (doubt that ever been changed).


Last week noticed a different behavior: while driving, after at a 4-way stop when about to accelerate, the engine stalled not starting anymore. The engine started again 10 - 15 minutes later (while waiting for the tow-truck )

Is the check engine light coming on? Have you had any codes pulled with an OBD-II scan tool under the driver side knee area? I have 127k on my 2003 3.0i and it has completely died on me a few times recently. It started right back up after pulling over. I cleaned the Mass Air Flow sensor and reset the check engine light that was saying PO172 lean bank 1 MAF. It is running fine now but when it dies the gas mileage has decreased. I do think you are changing the right part with the fuel filter. I hear that it is the cause of alot of issues. I have not done mine but I have run alot of STP and SeaFoam cleaner through it.

I know this is dumb but when was the battery last changed? These X5's have to have strong new batteries to run or fire up correctly. You need to check this out in the rear trunk under the spare tire. If older than 5-7 years it is probably another cause of no start.

No check engine light neither any error code stored. In my opinion the battery should be fine since it cranks the motor for long time with no power loss shown...

I may be wrong but sounds like the seals wen't bad on engine right under the camshaft. Usually if it won't start on the mornings and after the vehicle been sit for a while, it's most likely the seals.
Again i may be wrong. Just trying to help.

Check "spark sensor". Your symptoms happened to me. Battery and alternator and fuel were all good. Spark sensor had to be replaced for about $200. They also checked the wire harness but it was fine. Once they replaced the sensor, it started right up.

Folks,

thank you all for taking the time and respond my posting with suggestions and ideas.

I am glad to say the issue has been solved. It turned out to be a loose relay in the DME box (located in the engine compartment next to the firewall).

Here are the troubleshooting steps followed that led to fix the issue:

1. measured fuel line pressure (this saved me from a spending approx.$2,000 on replacing fuel pump - recommended by the BMW dealer - LOL such a jokers BTW); this step could be accomplished by hooking up a fuel pressure measure gauge ($40) to the rail.
2. checking the spark signal: for this I've taken an extra spark plug, grounding it slipped the ignition coil on it and cranked the engine - this test showed clearly spark was present.
3. checking the injector pulse: took a long screwdriver, set the tip on the injector body and cranked the engine; when the engine was in mood to run a distinctive clicking noise was present vs. when the engine didn't want to start no clicking sound at all....

the 3rd. step lead me to the conclusion, that when the car is acting up and don't want to start then the injector pulse signal is missing although there is fuel under pressure at the injector. This conclusion made me to open up the DME black box and started thumb pressing connectors, relays and stuff.

Since then I haven't encountered this issue again.

Let me know if anyone has additional questions or concerns.

Get some contact cleaner from Rat Shack and clean all the contacts. If the connectors or relays and other stuff wasn't making good contact chances are that there was some arcing going on and you can have some carbon build up from the arcing.