Help - faulty coil or....?

[Speedy23]

Out for a ride yesterday - after about 100 miles, the bike (2005) , which had been running perfectly until then just cut out in traffic. Started again on the button but refused to idle - it just died. Got it home (another 40 miles) by keeping the revs up when the bike was stationary in traffic etc. - once under way, bike ran OK no apparent loss of power or misfire, etc. Soon as I got back, I let the bike idle - it was very lumpy then cut out. Any ideas, please? I seem to remember reading somewhhere that this is a symptom of one of the main coils going faulty, as once under way the cylinder fires on the secondary (lower) coil? Is this correct?

Thanks.

 

[millard]

Hi Speedy
I had one primary coil breaking down under load but the symptoms were different to your.
It would start fine and pull ok if the throttle was used very conservaivley. If it was opened up it would spit and backfire like crazy.
I called the BMW dealership over Guildford way, Vines - tel 01483 207000, and the guy in the service dept was very helpful and more or less diagnosed it over the phone, so they might be worth a call.

good luck
Millard

 

[Big Nick]

Fuel pump controller on its way out?

 

[shugie]

If it runs fine at speed, but won't idle properly, I think I might start looking at the throttle position sensors.

You can reset them by turning the ignition on but not starting, fully open and close the throttle three times, then start.

 

[Zed3]

Don't want to be a harbinger of doom - but I had very similar symptoms on my 2005 GS a few months ago and after having gone through all the possibilities mentioned here it turned out to be disintegrating RH piston that took out two valves. Check compression.

 

[colinw]

Check the location and correct seating of the throttle cables, it is possible for one to become dislodged and this will cause the symptoms you describe, check the two cables that come out of the airbox, one each side of the bike>>

 

[The White Rabbit]

Sounds similar to my still undiagnosed problem which I havent had time to work on as busy playing on other bike, but have tried all the usual suspects. Be interested to know the outcome, coils have been suggested for mine as well, although mine doesn't run smoothly on throttle either.