2003 3.0d crancking over but not starting
 

My X5 3.0d E53 has started fine on first turn of key for the 10 years I've owned it, then last week it took 2 turns of the key, then yesterday it took 3 and now this evening she won't start at all. Starter turns engine over fine, battery fully charged so not that. Car has half tank of diesel.

Any ideas where to start investigating? Searched on here and other internet sites but nothing the same found. Any ideas?

Sounds like a fuel sender / pump / pressure regulator issue. Look into that system first. I'm not sure of the specifics of the 3.0d so I can't help in detail I just know diesels.

Is it throwing any codes?

can only be one of two things i would think, glow plugs or fuel pressure.
not much else in a diesel, no spark to worry about, it just squirts the diesel in and compresses it till it goes bang, when the motor is cold it relies on the glow plugs for that initial ignition

Cars need 3 things to start..

Fuel
Spark
Air

I would assume it's not an air problem as it would be very hard to get an obstruction in the air intake. I would start by checking for fuel and spark. You can google plenty of different ways to test this at home.

this is not a petrol engine, this is diesel, no spark needed as the diesel fuel self-ignites under high pressure (same principle in the low- vs high- octane gasoline - higher octane=less "flammable" fuel, so it does not self-ignite in high compression sports' engines, thus, no knocking. AKI - AntiKnockIndex)

if the battery is confirmed good (how old is the battery? has it been discharged and then recharged? has it been load tested?) then the natural course of action is the fuel supply...

your location is not clear, but in the Northern Hemisphere we are in winter now, and the old diesel fuel used to "jelly" in cold tempertures... not sure if this is your case or not... but, as always, you go from the simplest solution to your problem to more complex... then, the fuel pump - does it prime the fuel lines? fuel filter...

I have the same problem. I have replaced the fuel pump in the tank, the pre-supply pump underneath the car and nothing improved. i have replaced the glow plugs, i have replaced the fuel rail sensor and still it did not start. i replaced the regulator on the front pump and still it would not start. Now i have removed the bosch pump in the front to get it tested because the diagnostic (DIS) reported a fault with the "fuel rail pressure". Good luck and pls let me know if you come right.:dunno:

After all that,just leaves the injectors ,wiring or ECU.I would still try another fuel rail sensor.just in case as its not unheard of that a new sensor is also faulty!
Not related ,to fuel pressure,but have you tried starting the car with spare key ?
Maybe immoLliser issue!

Thanks for all the replies.
Tried spare key - just the same.
Agree that I need to check if glow plugs are functioning and if fuel is getting to engine.

I am planning to try the continuity tests on the glow plugs - although heard they're hard to get at - gotta take off all engine covers etc.

Is there a simple way to check if diesel is getting to engine? unplug a fuel line somewhere?

I do notice now when the key is in the run position on the ignition I can hear what sounds like a pump around the area of the fuel tank/rear wheel - not sure if that is normal or bad sign!

As long as the pump turns off after a few seconds, that's normal as it' s priming the pressure, if it runs on and on, then sounds like it's a fuelling issue.

Pump continues to make the noise all the time key is in position 2, so sounds like a fueling issue maybe?