N47, fuel pump problem? Cutout

[PLuKE]

Hi folks.

Well I am after some help. My 520d N47 auto, it cut out on the dual carriage way at rush hour coming onto a bridge not a great experience I must admit!

Before it cut out, I had the car on cruise at 60mph, It felt the like car had a soft gear change, I felt something, but not a splutter.

Anyway, car wouldn't restart, and battery couldn't take much more cranking and said tranny problem, got recovered, very long story!!

I had the car read:-

4CA0 oil pressure switch plausibility

4BDA fuel pre supply pressure control

4590 Rail pressure plausibility delivered controlled

had them cleared and nothing, still cranks over and over.

I spoke with an Indy BMW dealer and they said fuel pump. I bought the car from a small garage, who seem to be trying to wash there hands with it, and said fuel systems aren't covered, but they might contribute, they need to talk about it.

Any ideas?

Is it worth buying a new fuel pump, Can I test it anyway without software? The replay seems to work, looks clean inside of it, but it does get warm when I tried cranking the car over.

Camchain seems fine, no nosies etc?

Thanks
Luke

[bearman68]

OK, I think the oil pressure plausibility switch is a red herring.
The problem appears to be with the fuel system.
In my experience it's unlikely the mechanical bits of the high pressure pump has failed (good news), but it does have several bits to make it work correctly.

Firstly it has a low pressure electric pump located on the underside of the car (I think). This is responsible for ensuring the HP pump has sufficient fuel. Does this start with you cycle the ignition.
Then the HP pump is controlled by an Inlet metering Valve. Essentially this switches the fuel on and off to the HP pump depending on the feedback from the fuel rail pressure sensor.
The FRPS sits at the easy end of the fuel rail on the LH side of the engine, just under the cover, It has 3 wires to it, and the central one is the feedback voltage. On ignition on engine off, this should read 0.5v, and on cranking, this should rise to 1.3v (and then the engine should start) This will tell you if you have a low or no fuel pressure problem. If it gets to 1.3v and the engine starts, or attempts to start, the reading on the FRPS will then indicate if you have a leak in the system (it will fall very quickly - possible injectors or HP Fuel Pump), or if the injectors are being inhibited by something else. (Will stay at 1.3v)
Hard to describe much more without data to be honest, but hope this helps a bit, and you can do these test with a simple multimeter.

[PLuKE]

bearman68 said:

OK, I think the oil pressure plausibility switch is a red herring.
The problem appears to be with the fuel system.
In my experience it's unlikely the mechanical bits of the high pressure pump has failed (good news), but it does have several bits to make it work correctly.

Firstly it has a low pressure electric pump located on the underside of the car (I think). This is responsible for ensuring the HP pump has sufficient fuel. Does this start with you cycle the ignition.
Then the HP pump is controlled by an Inlet metering Valve. Essentially this switches the fuel on and off to the HP pump depending on the feedback from the fuel rail pressure sensor.
The FRPS sits at the easy end of the fuel rail on the LH side of the engine, just under the cover, It has 3 wires to it, and the central one is the feedback voltage. On ignition on engine off, this should read 0.5v, and on cranking, this should rise to 1.3v (and then the engine should start) This will tell you if you have a low or no fuel pressure problem. If it gets to 1.3v and the engine starts, or attempts to start, the reading on the FRPS will then indicate if you have a leak in the system (it will fall very quickly - possible injectors or HP Fuel Pump), or if the injectors are being inhibited by something else. (Will stay at 1.3v)
Hard to describe much more without data to be honest, but hope this helps a bit, and you can do these test with a simple multimeter.

Thanks for coming back to me!

I will get my friend round tomorrow so we can at least eliminate items, awaiting a call back from the garage, to see if they are going to pay. Under buying rights, should they legally pay out, with it being a fuel issue? As they say that they only cover engine and gearbox.

Many thanks

[PLuKE]

I have check, on cranking 4.7 volts and 4.7 volts with just the ignition on, and fluctuating.

Lost!

[PLuKE]

Checked the fuel lines from under the bonnet, the black line jetted out fuel, checked all relays too.

I can't see it being a filter or even a pump now, as the car cranks over, without even a hint of coughing or spluttering to start up, just cranks and cranks, the battery is taking a hit now too, from testing things and trying.

I think I will have it towed to my local Indy BMW, and go from there, they can do some proper checks, they seem to things its the fuel pump by what faults of shown up.

But, I can change the fuel pump, but at £200 and it not to be that fault, then it becomes a problem...

[bearman68]

Check the 3 wires on the fuel rail pressure sensor again. Engine off ignition on, you should have 0v 5v and 0.5v on the 3 wires. I may have the order wrong, but if you have about 5v on 2 wires (as you imply), that's your problem. (Pressure sensor shorted - very unusual)

[SebringMan]

How long have you owned the car for?

If it is less than 30 days you are fully entitled to get your money back.

[PLuKE]

Hello again.

I took the plug off the sensor and tested the voltage on the middle wire on the plug (4.7 volts). I didn't check the other two wires. is this how you check the voltage, or does it need to be plugged into the sensor? If it's plugged in I cant really jam the prong of my multi-metre in anywhere to touch a wire, unless I poke a cable strand in from the back of the plug to make contact?

Thanks
Luke

[bearman68]

PLuKE said:

Hello again.

I took the plug off the sensor and tested the voltage on the middle wire on the plug (4.7 volts). I didn't check the other two wires. is this how you check the voltage, or does it need to be plugged into the sensor? If it's plugged in I cant really jam the prong of my multi-metre in anywhere to touch a wire, unless I poke a cable strand in from the back of the plug to make contact?

Thanks
Luke

Agh, no the sensor needs to be plugged in. Go raid your Mrs sewing box, and find a big strong needle. Put your MM probe into a 'chocholate block" -not sure what the proper name is, and the needle in the other side. The needle will be thin enough to slide down the side of the wire into the little multiplug, and read the correct voltage. (ECU compensates if the sensor is not connected). Don't pierce the wire unless it's a last resort. It will corrode in due course, and leave you with all sorts of problems.

[PLuKE]

bearman68 said:

PLuKE said:

Hello again.

I took the plug off the sensor and tested the voltage on the middle wire on the plug (4.7 volts). I didn't check the other two wires. is this how you check the voltage, or does it need to be plugged into the sensor? If it's plugged in I cant really jam the prong of my multi-metre in anywhere to touch a wire, unless I poke a cable strand in from the back of the plug to make contact?

Thanks
Luke

Agh, no the sensor needs to be plugged in. Go raid your Mrs sewing box, and find a big strong needle. Put your MM probe into a 'chocholate block" -not sure what the proper name is, and the needle in the other side. The needle will be thin enough to slide down the side of the wire into the little multiplug, and read the correct voltage. (ECU compensates if the sensor is not connected). Don't pierce the wire unless it's a last resort. It will corrode in due course, and leave you with all sorts of problems.

Thanks for your replies!

I will go out and check within the next 30mins and see, need this solving quick!

The garage seem to be washing there hands with helping resolve this issue, and paying/contributing!

Will report back!

Thanks
Luke

[PLuKE]

Ok,

Checked the voltage

0v
0.3v
4.9v

Is there anywhere else I can check?

http://forum.bmw5.co.uk/topic/126136-n47-fuel-pump...

I have checked #16 plug which is the pressure sensor

Is there any point checking #15 plug? and what would the voltage be if so?

Many thanks for your assistance!

[bearman68]

PLuKE said:

Ok,

Checked the voltage

0v
0.3v
4.9v

Is there anywhere else I can check?

http://forum.bmw5.co.uk/topic/126136-n47-fuel-pump...

I have checked #16 plug which is the pressure sensor

Is there any point checking #15 plug? and what would the voltage be if so?



Many thanks for your assistance!

That 0.3v is not correct - ie it should be 0.5v. The car will not start with 0.3v on that wire. 0.5v is a test voltage, and it must pass this voltage test before it is 'allowed' to pressurise the rail, and it won't start until you have the correct pressure in the rail.
I've never seen 0.3v on this sensor before. (And I test then day in day out). I would suggest you check this voltage very carefully again. If it's confirmed as 0.3v, and you are sure everything is good, you need to change the pressure sensor. - but check again to make absolutely sure. (I might have repeated myself here, sorry)

[PLuKE]

Thanks,

We will have to check that out again then, we used pins down the plug and tested a couple of times.

How does the sensor come off? As it's on the rail.

Thanks for your help!!

[PLuKE]

Brown/white = 0v. Yellow/white= 0.3v. Blue/white= 5v.

[PLuKE]

On cranking the engine, I can hear a spark noise too, somewhere around that paticlular area. I am tempted to replace the sensor, but for £110 it's a gamble if it isn't at fault.

Many thanks for your assistance once again!

[bearman68]

If you're absolutely sure it's 0.3v, and you can't make it different, the sensor is the problem. That is a faulty reading, and one the ECU will recognise and reject. HTH

[PLuKE]

On cranking the engine, I can hear a spark noise too, somewhere around that paticlular area. I am tempted to replace the sensor, but for £110 it's a gamble if it isn't at fault.

Many thanks for your assistance once again!

[helix402]

£30 for a used one on eBay.

[PLuKE]

Would a faulty fuel pump give a lower voltage reading on the fuel rail pressure sensor? ( usually 0.5v, I get 0.3v)

Looking at the clear pipe under the bonnet for the fuel line, it seems to have bubbles moving on cranking, that move slowly, but no fuel moves with ignition is on.

Many thanks

[PLuKE]

Would a faulty fuel pump give a lower voltage reading on the fuel rail pressure sensor? ( usually 0.5v, I get 0.3v)

Looking at the clear pipe under the bonnet for the fuel line, it seems to have bubbles moving on cranking, that move slowly, but no fuel moves with ignition is on.

Many thanks