warm/hot starting problems
 

2011 x5 40d
Starts ok when cold but long crank or just cut out when trying to start when warm engine
Been suggested fuel injector leaking or even fuel pump
But dont want to start throwing money at different things
So anyone advise please

Can you do the equivalent of key on engine off beofee you start?

Eg press start button no brake get the fuel pump to prime before you hit start? If so, it indicates a problem with FPR not holding pressure on the low pressure side of high pressure fuel pump.

I don't work on any diesels I've just read a bunch and recently replaced wifes FPR when it was having starting issues.

Is there a place to test the fuel pressure between the two fuel pumps on diesel engine?

I would look at electrical related to the cooling system and temp sensors.
I had a Volvo 850 that would fail to start when it was cold. Turned out to be a corroded connection to the cooling fan relay that somehow fed bad data to the ECU on the status of the cooling system.

Currently have a 3.0 e53 and I have looked at a number of things on this vehicle. Starts fine when cold but have to lightly press on the accelerator to get it to start sometimes when warm. I believe the issue to be the coolant temp sensor. This is literally the last piece I have reviewed. Temp sensor is in my tool box waiting to be replaced.

Both of the petrol vehicles are far different from a diesel but in both instances the ECU is using the ambient/coolant temp resistance variables to meter fuel/air mixture when starting.

Not recommending throwing parts at unless the temp sensors are cheap, but would certainly see if there are readings you can take via a multi meter or ISTA/D and compare.