Thought I'd throw this one at you just incase anyone has had similay trouble with their K75. My K75S has slowly developped a very irritating fault whereby whilst cruising at say 60 or 70 MPH on mororways the enging starts to stall. Initially it would re-start again and I could carry on but as the fault has developped over a period of several months it has now got to the stage where it will cut out, the machine will coast to a standstill and whilst in this condition it will not re-start. All the warning lights are showing when in the stalled condition indicating that the electrics are working up to a point. I then have to wait for about a minute and it will re-start and apart from a couple of coughs will then get me home. It is extremely intermittent and I have noticed that just toodleing around town in traffic and speeds less than say 40 MPH it seems fine. It only seems to play up on longer journeys involving higher speeds and revs.

Any suggestions gratefully accepted.

to me sounds like the fuel pump ...as there is no other indication from what you say .

i would be checking the tank connector under the right hand side side panel ....a few of us have had issues with this electrical connection ...

check to see if the 4 pole connection is clean , tight and mounted so that there is no strain on the cables (can promote movement of the connectors ) i have found that the socket part of the connector tends to expand and a loose fitting occurs ...

whilst idling around the intermittent connection will still give fuel supply for a few seconds ...but at speed it is in high demand and more noticeable ,,,if not crititcal to good running

my 10 cents worth

good luck !!

Charlie may be right. This four-pin connection is the one which clips to the front right corner of the ECU under the seat. Remove the right hand side panel (carefully) and there she'll be. Check the four wires, their connectors and use Deoxit too. I found one of the four pins female side was distorted making an intermittent contact and it would often not start at all for five, ten minutes after just running perfectly, then start up like a beautiful woman having a bad day.

I will check this connection but I should have added that when the engine now refuses to start it doesn't actually turn over on te starter. I was a bit inaccurate with my description of the fault but from the "feel" of it when it dies it ndoes feel like an ignition fault but as the fuel is an injector system then I guess the failure of the fuel pump would give the same impression.

Thanks for your help.

I will second all of the above solutions and will add that the water temperature sensor could be faulty too. (maybe not the sensor but at least the connection).

CF

I had a fuel pump die on me about 4 years ago and it had the same symptoms. I initially put it down to a very hot day and fuel vaporization but it was the pump as I found when it died a week later in the rain and cold. i don't have good menories of that break down as I was stuck standing in the pouring rain on a very narrow bit of road and wasnt sure if the cars could see me or for that matter even looking. I couldn't even get far of the road due to a large culvert. Fun Fun Fun

oh!!! more news ....the starter wont turn over ?

better pull the starter out while your down in there ...(isnt hard to get to ) and clean the brushes ....comutator etc ....

this is a known... um.... "feature" (dont want to say fault) with the k bike design .....in esence the starter motor provides a ground path when not in operation ....which pulls in the "load shed" relay ...if this connection is lost ...all sorts of random things start happening ...including some of the things you may be experiencing.


the brush set as a spare part comes with the earth side brush contacts welded to a backing plate ....and the positive side is a standard type fit

some times the actuall length of the brush ...is the issue ...as the springs lose force for positive connection when the bushes are particualy short

the brush set isnt real expensive ...and if i was going to do it ...i would be putting new ones in, in the first instance ....but some have found just cleaning it all up works well

Just a quick update on this. The K75 still continues to stop whilst running and refusing to turn over again until left for a few minutes. I've taken her off the road now as I intend getting the K100 MoT'd for the summer (when summer eventually arrives here in UK) and have done what Charlie 99 suggested and re-newed the starter moror brush assembly. Only time will tell if this will provide the cure. I'll update when the 75 is back on the road.

Well I went for a curry with some mates in Sittingbourne last night - a round trip of about 100 miles. The 75 ran faultlessly all the way there and cruised like a dream at 70MPH along the M25/26/20.
On the way back it dies just outside Sittingbourne. The usual symptoms: engine cuts out, bike crawls to a halt, oil and ignition lights showing but the starter button wouldn't start the engine. So obviously it wasn't the starter motor brush assembly.

One conclusion I have come to is that, having read the other similar thread under electrical faults, it probably isn't the engine kill switch. When this switch is in the "kill" position the oil and ignition lights don't show. But they do when my K75 stops. What does produce similar symptoms is when the Spyball engine immobiliser/alarm is in operation. Infact until it is disabled with the remote control it produces exactly the same symptoms: the oil and ignition light show, the bike lights can all be switched on, but the engine won't turn over. I'm beginning to wonder if it is the engine immobiliser that is eratically killing the engine. Anyone know how to bypass it or remove it completely?

I believe that the engine immobilizer send a signal to the EFI that the engine is overheating. This will prevents the bike to start but...... If the engine is running, it won't stop it.

The first area of concern would be the plug of the EFI computer. It's a common problem as it get dislodged from the computer when going over a bump. (Sometimes the clip doesn't help).
Other problem could be the Hall sensor cutting out when hot.

CF

i had the same thing happen to me over the course of about 100 miles...
my starter failed (brushes completely worn away). but of course i wanted to go for a ride with a pal...we went 100 miles and 2 miles from home my bike just died (as if someone pulled the connector for the fuel pump).
got it home, purchased a starter and the fuel pump seemed fine. I rode another 100 miles and fuel pump finally seized.
currently with the starter and the new fuel pump she seems to be running fine

dbikers wrote:i had the same thing happen to me over the course of about 100 miles...
my started failed (brushes completely worn away). but of course i wanted to go for a ride with a pal...we went 100 miles and 2 miles from home my bike just died (as if someone pulled the connector for the fuel pump).
got it home, purchased a starter and the fuel pump seemed fine. I rode another 100 miles and fuel pump finally seized.
currently with the starter and the new fuel pump she seems to be running fine

But presumably if the fuel pump fails the engine would still turn over, albeit the engine won't start?

But presumably if the fuel pump fails the engine would still turn over, albeit the engine won't start?

Agreed....exactly what I thought. in my case I had both a bad fuel pump and a bad starter' What are the odds, right?
..kinda sounds like you may have more than 1 problem
do you have anything else strange going on electrically (headlight, turn signal, horn...)?

When coming home form Sittingbourne you said you pushed the starter and nothing happened as in starter does not work, or you pushed the stater and it wound over but the bike didnt fire?????????? Remember if the fuel pump is trying to suck up stuff it will not work for you. if you shake the tank or bike and dislodge the debrea and it starts you have found a solution in the tank, sometimes it just takes a tap on the filter to fix it and that indicates the filter is clogged. if its the pump then its getting clogged inside and thats difficult to fix, but a replacement is the go then

Parked on the side of the road was the side stand deployed? or had you a neutral light showing. sometimes it pays to turn it off and back on to set it up to start. Perhaps the clutch needed to be pulled in to have it start that day

K75cster wrote:When coming home form Sittingbourne you said you pushed the starter and nothing happened as in starter does not work, or you pushed the stater and it wound over but the bike didnt fire?????????? Remember if the fuel pump is trying to suck up stuff it will not work for you. if you shake the tank or bike and dislodge the debrea and it starts you have found a solution in the tank, sometimes it just takes a tap on the filter to fix it and that indicates the filter is clogged. if its the pump then its getting clogged inside and thats difficult to fix, but a replacement is the go then

No. The bike initially starts ok, then in this instance after a couple of miles the engine just cuts. It is very random....I can ride for over a hundred miles and it runs fine. When the engine cuts the bike coasts to a halt and the engine will not turn over. Both the ignition and oil pressure lights show (which they don't if the engine cut switch is operated). When the starter button is pressed in the fault condition the headlamos don't dip....indicating that the load shedding relay isn't operating. After a few minutes it will then restart and will run fine until the next time it ciuts out.

Check the earth connection under the fuel tank. It's on the left side of the frame on the top tube, there are 4-5 brown wires connected to the frame by a 6mm screw. Clean the terminals and redo the connection tight.

I had problems on the K100. I didnt think fuel pump would be problem as it was dealt with in June 2010 and new filter fitted.

The starter motor would not turn over but fuel pump was pumping fuel, return fuel could be heard flowing into the petrol tank. This was erratic, bike would start and then run fine and at some point cut out, sometimes then it would restart and sometimes not.

After replacing the starter relay and load shed relay Inge K here was very helpful. Finally replaced ICU under the tank/headstock and problem solved with a replacement unit from Motorworks. I did also clean up all of the connections under the tank but the problem remained unti ICU was replaced.

The starter motor is very easy to remove and dismantle and repair, it is even an easy roadside repair if you had spare brushes in your toolkit.

starter motor brushes ?....bad earth to starter motor ....

if ...when this next happens (carry a multimeter ..obviously ) test the positve terminal of the starter motor and ground (where the earth cable bolts to the gear box )

there could be 2 outcomes ....

if the positive side of the starter does not read 0 volts ...

a> the brushes are high resistance and need a replacement - refurbish

b> the earth reference to the starter has become high resistance ....maybe a second ground cable could be attached to the body of the starter ...and run to the earth point

2> if it does measure earth

a possibility could be

a>the hall sensors in the timing cover (end of crankcase cover) have become faulty \

b>the electronic ignition module could have an issue , or might not be earthed properly

c> some high resitance in the ignition coils circuits (ground side / corrosion perhaps ? )

d>: the positive fused sections of the cabling supplying the coils ....and injectors could be intermittently faulty ?



just some suggestion of things to test ...properly

And when have the tank removed, check the ignition ECU connector for corrosion, if it got proper ground.
The negative side of the starter relay coil is grounded through the ignition ECU.

I would suggest that you establish a temporary test wire at the negative side of the starter relay coil.
Lay the other end in the tool tray, next time the fault occurs, measure if you got ground on this wire.

Just a quick update on this problem; it seems to have been developping for years!
I replaced the starter brushes and the starter motor end plate as suggested but the problem persists.
As I predicted the problem has become more regular now and the poor old K75 is now conking out several times in the course of a 10 mile trip. As the weather here in UK has got more mild this weekend I shall be checking out the other suggestions this week. I'll keep you posted.
Thanks once again for your helpful tips.

I spotted this thread becoming active again and relaised that my problem never reappeared after changing the ICU unit at the headstock. It was extremely frustrating at the time.

I had replaced starter relay, load shed relay, stripped and cleaned the start motor and brushes, opened and remade all the electrical earths and the problem remained. Fuel pump and fuel filter only had about 4k miles on them. There seemed to be a number of faults rather than one simple one [eg battery was known to be good, sometimes starter would work, sometimes not, but when it didnt work the fuel pump worked fine with good fuel pressure] but the one thing in common was the ICU was a potential problem in all of them. I dont have immobiliser or alarm fitted.

I got a replacement from www.motorworks.co.uk for about £50 [cheaper than paying BMW to test it] and when I got it I cleaned up all the contacts until they were nice and shiny. This was then fitted and problem never repeated itself.

However, I never tested the original one which I still have and am more than suspicious it could have just been the connections. It seems a lot of different sensors and switches are routed through it and a bad connection here can make a sensor or switch appear faulty when its not.

92kk

I would be cleaning the ignition switch , solved my problem with similar symptoms .

Thanks for that feedback, 92KK. The sun is shining brightly in Sunny Surrey so I spent some time on the bike this morning. With the tank off I was able to see the earthing point on the left side and removed the bolt and cleaned all the connections there as suggested by another poster above. I then removed the ignition control box.

The screws holding the lid on had obviously been treated with some extra strength ScrewLock in the factory as they were impossible to remove without ruining the cross slots and writing off one of my favourite screwdrivers so I had to drill the heads off them. Inside the circuit board looked in very good shape. I was particularly looking for any dry solder joints that might have developped but I must say it looked as good as it did when it came out of the factory. I did consider swapping it with the ICU in my K100 as the part numbers cast into the lid were all exactly the same but down in the corner the K75 box has "3 Zyl" and the K100 had "4 Zyl" so I didn't. Whilst I had it out I removed the pcb from the ICU box, which involved de-soldering the three power transistors and the multi edge connector pins, and had a look on the inside of the board for any signs of any components running hot. The only possible suspect was a voltage regulator (LM340T) but again inside it looked almost brand new. So I just ran the soldering iron over all the pcb pads on the print side of the board and reassembled it.

I also took the precaution of spraying some Colclene into the multi connector in case any pins in there were corroding but they all "looked" fine. The bike fired up again more or less straight away once some petrol had reached the fuel rail so I shall have to take it out for a run this afternoon but only time will tell if it has provided a cure.

I have just reread this thread and the only thing that can cause it to stop running and then prevent it starting by not letting the starter work is the lack of earth to the Fuel Injection relay which stops it and a lack of earth to the starter relay which prevents it starting and that earth is on the pin No1 of the ICU and goes to ground at the eth connector under the tank.
Which is what Inge said a few posts back. He suggests hooking a wire up to check it which is all well and good but a quicker way would be to connect a wire from pin No1 on the ICU through a switch to the neg of the battery and when it stops just flick the switch and see if it goes immediately, if it works and I suspect it will then give it a few tries each way on the switch when it stops and each time you go out make sure the switch is off so that if the fault appears you can recheck if it works by flicking the switch.
It is possible that you have 2 separate faults but highly unlikely.
Because the relays only take 40milliamps to operate them they will work even with a bad earth untill it starts getting hot from arcing, it could be a broken wire or bad crimp joint it doesn't have to be right at the earth point.

Thanks Rick,

If it is a poor earth between those two points I could just replicate the existing earth cable with a secondary one and save all the possible messing around with switches and meters. If it fixes the problem than that's good enough for me.
I went for a spin around town but it might not have been for long enough. I shall be using the K75 to go to work on Thursday when it will get a proper test.
I also noted an oil leak from the rear suspension damper as well today. Wish I hadn't started now.

Yeah you could do that I was just thinking of prooving it so you know it really is fixed. Intermittent electrical problems are what keeps the shrinks in a job.

G'day,Had a similar problem on my 75 a little while back. Random cut out of electrics with ignition lights dim. Inge put me onto to the ignition switch link under 'The odd electrical problem" Took the ign.switch apart as per link, cleaned it and resolved the problem. Cheers Tom

It's still cutting out.
So I think the next step is to instal some secondary earthing to the ICU as suggested. I might also take out the Spyball immobiliser next time I've got the tank off. The symptoms when the bike stops are the same as when the immobiliser is in action (ignition and oil lights on but won't turn over the engine on the starter). I've read elsewhere that spyball immobilisers always play up eventually. I've also read that it can be a nightmare removing them.

About 2 hours after posting the above I attempted to ride the bloody thing to work and it cut out about five times in the first mile. At the fifth time I sat there repeatedly pressing the start button with no response and then, in utter frustration, I thumped the side panel in the vicinity of the relay box with my clutch hand. The bike sprang into life, started and rode perfectly all the way to work for the rest of the ten mile trip.

So on Wednesday, when I have a day off, I'm going to take a closer look at all the connections and earthing arrangements in and around the relay box. With particular attention to the starter relay as suggested by Inge, Charlie and Rick G.
I feel there is light at the end of the tunnell now.

Edit:
It rode faultlessly all the way home again last night.

Good to hear that it started, I know it can be bloody disheartening.

As you are in London, consider contacting Neil Harrison (known on the internet as Steptoe).

Neil is an independent, former BMW employee who knows most of what is worth knowing about all things BMW. His rates are good if you get to the point of handing it over for him to look at.

I know Neil and would recommend him to anyone.

He mainly specialises in GS models these days but used to maintain a fleet of K100 and K75 models for a company (and still runs a K100RT as a courtesy bike).

Contact him via:

http://www.gsshop.biz/

I don't think there is anything automotive that is more fustrating than an intermittent electrical problem.
I have been chasing one for 18 months now only to find that it probably isnt electrical after all.

I managed to spend several hours on the K75 today. I replaced the leaking rear suspension damper which was a job in itself and required me fabricating a home made tool to compress the suspension spring. I'll post details about that in the "Special Tools" forum.

Back to the engine cutting out.
I've a feeling Rick G was right on the money with his diagnosis. Once again it was off with the tank (I'm getting quite proficient at that now) and a closer look in the relay box. On Rick's advice I decided to check out the earthy end of the strater relay. Two wires (black and yellow stripey) came out of the connector at the relay but they disapeared into a single black cable via a soldered joint covered by some insulation tape, and this black cable went off to the SpyBall immobiliser. So that was how the Spyball installer had arranged the imobilisation. Infact it started to make more sense when I thought about it: the symptoms, as I've said before, were exactly the same as when you use the remote to re-enable the machine and infact when I thumped the bike in frustration the other day it was infact nearer to the Spyball control box than the relay box which is a bit further back. I'm assuming that within the Spyball control box there are some relays and presumably the contacts could just go crappy.

So I disconnected the single black cable going off to the immobiliser and ran a separate cable from the earthy side of the starter relay off to pin 4 of the fuel injection control unit, and another to pin 1 on the multiconnector to the start button. This effectively replicated the correct wiring as shown in my Haynes manual. Only time will tell if it is a permanent cure but I'm feeling quite optimistic about it now.

Well..... maybe not over- optimistic!
I rode the bike to work this morning and it died after a couple of miles. However, the engine spun on the starter straight away but wouldn't run. After the now customary thump on the side the engine started and ran for the next 8 miles.

It would appear to me now that the Spyball engine immobiliser not only prevents starting the engine which I have seemingly overcome with my re-wiring as described in yesterday's post but it also stops the engine by either killing the injector solenoids or maybe even the fuel pump. I think the only thing to do now is remove The Spyball unit entirely. There are a lot of blank black wires coming out of the Spyball box with no identifcation so if I'm not careful I could end up with a dead bike that won't start at all.

I had similar symptoms with my K75s a couple of years ago and chased the problem for weeks until I stumbled on the source of the problem.
There is a plunger type switch for the clutch lever and one of the two yellow wires had broken was intermitenly making contact. I never would have seen it if I hadn't been taking the lever assembly apart.
Chris

I have never seen or even heard of the spyball but if I was going to make an immobilizer for a K bike then that wire that I pointed to would be the one to interrupt for a good kill.
I would now just remove the thing entirely and feed it to a convenient dumpster or fertilizer for an oyster farm.
It probably has other wires interrupted so you may need to have a good schematic wiring diagram with colours etc. if you want one PM your email address and I will send one. If you have a look in the downloads section (Crazy Frog aka Bert has a password) there may be a schematic.

I removed the whole cursed thing this morning. In addition to interrupting the starter relay the Spyball also cut out the 12 volt supply to the injector relay in the relay box. So mystery (hopefully) solved. In the end there were indeed two separate faults but both with a common cause. Thanks to everyone for their helpful advice.

I've just noted the date of when I started this thread - June 2011. It's only taken me nearly two years to sort this out!

Has anyone mentioned the air flow meter connector . I have just been through the same symptoms and found these connectors very green and corroded cleaned them up and problem solved . Tried changing pump ,pump relay all the usual k gremlins before discovering this , hope it solves yours as it took me a lot of rooting around to sort out. grrrrrrrrrrr.