Hi,

  I recently had a couple of cut-outs while riding that brought me to a stop. After a minute I was able to restart until it happened again. After a while it stopped happening and I thought I was OK.

Wrong.  Yesterday I was unable to pull away. Since I have been unable to start the bike.

The problem is that the fuel pump is not starting. No juice , no start.

I have traced back as far as the pump relay , which is getting power but is not getting the other side of the coil pulled low by the control box. Following the circuit it seems that one side is permanently fed with "12V" once the key is on and the kill switch is set to run. This much is fine.

So I hit the black box.

Is there something else that the controller is sensing that I should check?

There must be a pressure sensor somewhere since the pump does not run continually until I start the motor. But for now it does not start at all.

Any suggestions?

TIA.

[Please send food and water , I'm stranded in the sticks with no transport.]

There you go..... We already took care of the most important... With that you can survive for a couple of days.

I read on another forum about an undocumented security feature of the K bikes. They will not start if the engine is overheating. Could it be the water temperature sensor having a problem?
In order to unplug it, you have to remove the radiator.

Just a couple of simple things to be checked:
Are the fuses correctly seated in their sockets.
Is the connector for the fuel injection computer securely connected to the computer?
Is the load shed relay working? The 3 relais (headlight/load shed , fuel pump and horn) are the same. Have you tried to switch them to test?

I don't believe that there is a pressure sensor. The pump will turn when you push the starter button. Then, when the engine runs, the FI or ignition computer will power the pump.

If you are still stranded in 2 days, let us know and we will make a collect to send you food by courrier.

Good luck and let us know how you are doing.

Bert

thanks , the food looks delicious.

you are quite right there is no pressure sensor. I was incorrectly recalling what happens on power-on. In fact the pump is energized for a couple of seconds when the starter button is pressed but stops if the motor does not pick up. It's a timer delay , I was infering it was stopping because the pressure was tested.

I have been able to confirm that the control electronics is energizing the pump relay when I dab the starter, so that's OK. Equally the pump starts when I stick 12V on it's left hand fuse contact.

So at least I know that I have an intermittant fault somewhere that's blowing fuses. Could even be the pump itself.

That's going to be a bitch to find but at least I'm nearer to understanding the problem.

Thanks for you help (and the vittals ).

Sorry, I was wrong!
There is a pressure switch!

This is the #10 on the picture. It is listed on ETK as a pressure switch. (BMW part # is 12 63 1 459 416) and the cost is about $18.00
I believe the brown wire is connected to port #5 and #13 of the fuel injection computer.

Peter sent me a private Email about his problem and I would like to share my opinion on this board

Here is his Email:
many thank for you efforts. I have managed to determine that the fault
lies in the tank area.

There is an intermittant short circuit (or very heavy current drawn) by
something in the tank, that is the problem.

Since my BMW circuit diagram shows four wires going to the fuel level
gauges then two connections from there to the pump it remains a mystery as
to how these elements are connected in reality.

I see only a few possibilities now:

1/ Occassional short in pump itself
2/ Mechanical lock up of pump causing it to draw a very heavy stall
current.
3/ A short in the wiring inside the tank leading to the pump and/or
sensors.

I'm going to have to go fishing in the tank again to see whether I can see
any evidence of a fault or some grit in the pump gears. Maybe the pump is
tired and shagged out and just keeps locking up mechanically.

THIS IS MY SUGGESTION TO TRACK AND SOLVE THE PROBLEM:
I don't believe there is a problem with the fuel level sensors as they are working solely on ground. I tend to agree with you that the problem comes from the pump or ..... the pressure regulator.

Think of the principal of a pressure system:
A pump delivers only flow and no pressure. (Think of a garden hose, you get only flow at the pressure delivered by the water commission. If you start to restrict the flow with your finger, you build more pressure).

In order to create pressure, you have to restrict the flow. This job is handle by the pressure regulator. It is pre-set at 36 PSI and stay close until the pump built the 36 PSI. When the pressure goes over, the regulator opens and dumps the residual pressure to the tank. It then closes back and let the pump build pressure again. This operation could be repeated 1000s of times per minute.
What if your pressure regulator (also called a relief valve) get stock and doesn't relieve the pressure built in the circuit?
The pump will try to push more flow to increase the pressure and open the regulator and it will come to a point that the motor of the pump will draw so much power that the fuse will blow.
It is only 2 solutions to check it:
To put a gauge in line and monitor the fuel pressure or to try another relief valve.

Here is a picture of the relief valve located on the back of the fuel injection ramp.

Thanks for all the help. I found the problem, it was indeed a short-circuit. The positive terminal connector of the pump was very close to the metal neck of the pump output. I don't understand why this was an intermittant fault but there was clearly arc traces on the metal.I'm damn luck this was happening with a full tank. If the fuel level had been low enough for this area to be out of the liquid petrol and in vapour laden air mixture I would probably be riding to Valhalla on a fireball by now!A fuse is of  no protection here, you only need one first spark to go out like a jahadist on his way to a date with 79 virgins.I'm lucky to still be here. ALLAH AKHBA!Sorry for the lack of formatting , this forum software sucks and keeps messing with what I write. 

Hi Folks,
To avoid any fears what we have seen here is a demo of explosive limits. It always seems odd to have fuel pumps and fuel gauge senders in a fuel tank full of vapour and would be suicide but for one odd thing. Below a certain concentration and above a certain concentration of fuel vapour in air they will not ignite those levels are called the explosive limits. 1.4% is the lower level and 7.6% is the upper level the systems work on the concept that power will be off when the tank is vented by refuelling. The effect of explosive limits can be seen with the video of the girl getting a static discharge spark igniting the vapour from her fuel tank which is refilling. The flame does not go back into the tank and detonate that as there is too much petrol vapour in there for that to happen but outside well she learnt her lesson.

Bert, I think the pressure switch you mention is the vacuum advance which was quickly discontinued on later models due to its lack of effect and on mine I have disconnected the plug for nil effect.

Pins 5 and 13 on the FI controller appear to be connected together and then to ground, which also provides the ground for the airflow meter.

Regards,

Phil

Check the grounds I know I keep wittering on about the grounds but as the EFI systems run their sensors at low voltages and currents only a small resistance will cause a problem. There is another problem potentially at work and that is the extensive use of silver for contacts in plugs and sockets. One thing I discovered when I was an alarm technician after working on micro resistances at Imperial College previously was that silver only works well long term as a contact material when there is a current of around an ampere plus going through then it becomes essentially self cleaning, at low currents it can go open circuit and the effect is made much worse in geothermal areas. As an example one of the banks rarely gets more than a fault free 24 months on PC's in Rotorua NZ.
Regards,
K-BIKE