3.0d only priming intermittently
 

Looking for some help as I am at my wits end.

I have an intermittent starting problem with my 2006 3.0d.
When trying to start I get “Fuel injection system” warning come up and you cant hear the fuel pump prime.

So I then turn it off and try again until I hear the fuel pump prime. Once it buzzes the warning doesn’t come up and the car starts straight away. Some times it starts first go and sometimes it takes twenty turns. It is not getting progressively worst and does not show any sort of pattern.

I changed out the fuel pump thinking that it was the culprit but no change. I swapped the horn relay with the pump relay and no change. I have a Foxwell scanner but it is not showing any codes that offer any help.

Can someone tell me what tells the fuel pump to prime or offer any other suggestions to try?

Thanks

When you talk about fuel pump do you mean in-tank pump or inline pump under the vehicle?

DDE activates the relay for fuel pumps.

https://www.newtis.info/tisv2/a/en/e...-pumps/hVkPC3B

Thanks for the reply. I presume it’s the in tank pump I can here prime. Does the fuel pressure sensor have anything to do with telling the pump to work?

There are two electric fuel pumps on the M57TU 3.0d - one in the tank (as for the petrol E53 models) and another in the fuel line immediately after the tank, just before the fuel filter. The in-line pump actually looks a little like the fuel filter but the giveaway is that it has an electrical connector on it....

https://www.newtis.info/tisv2/a/en/e...l-pump/EF7Xpz7

Actually, there is a third electric fuel pump - for the auxiliary heater. Not relevant but just sayin' ;)

Yes I am aware of the three pumps. It’s the in tank pump that does not prime every time, but as soon as you can here it it ends up starting.

The in-tank pump (this was renewed?) is only needed when tank is below ~1/3 (transfers fuel from other side of the saddle tank. Inline fuel pump (Nr.1 in diagram) is what you can clearly hear when you turn on ignition. There is no sensoring for supply pressure on these with M57N engine so the only code it could give is for low rail pressure when there is not enough supply feed for HP fuel pump. DDE activates fuel pump relay feeding both electric pumps when you turn on ignition to pos. 2 and keeps it activated as long as engine is running.

https://www.realoem.com/bmw/enUS/sho...diagId=16_0567

Yes in tank pump replaced. So you do Not think the fuel pressure sensor has anything to do with it and I should replace the in line pump?

Do you mean rail pressure sensor? It has nothing to do with fuel pump relay activation.

If the in tank pump doesn't spin every time it's almost certainly at fault. You can test this by measuring voltage with back feed pins or poke through the insulation at the pump when you first try to start.

If you get voltage no whirr 100% the pump is bad. If you don't get voltage it's almost certainly the pump relay.

Those are the only two options I can. Think of that will give you your symptoms. Loose wire somewhere could give you a non whirr but that won't auto correct from just key off key on.

You could proactively swap the pump relay and see if that cures the problem but if it's intermittent that might just leave you stranded somewhere

I have changed the in tank pump and the symptoms are still the same. I also changed the fuel pump relay and that did nothing.