R1150 RT engine cuts with sudden increased throttle opening ie overtaking!!

[BeemerKOS]

I'm new to this forum having just purchased a GS911 so any help would be appreciated.
R1150 RT '04 42K miles, Has recently developed a fault of the engine cutting when opening the throttle to overtake around 65mph in 6th gear. Immediately closing the throttle picks up the engine and with more gentle increase in throttle will happily accelerate to 80+.  Have swapped out stick coils with known good from the GS. Cleaned out the TBs, Reset all the clearances, reset the TPS using zero=zero and the zero does not equal zero checked the fuel flow from the pump problem still there. So bit the bullet and bought a GS911. Not having the correct values to all the parameters I can only look at the relative changes to each as I change throttle, engine temp etc and all seems to be working OK in the garage with no engine load. Only thing I can't check is fuel pump pressure.
Has anyone experienced the same and any ideas as to the problem?

[panason1c]

My guess would be the electronic fuel pump controller faulty

[mike d]

My guess would be the electronic fuel pump controller faulty

There isn't one on the 1150, the fuel pump controller appeared with the R1200's.

When was the fuel filter last changed?

Mike

[BeemerKOS]

Mike, Fuel filter changed 1k miles ago, fuel flow is no problem but cannot check the pressure.

[Jughead]

Does the motor die completely or does it just refuse to accelerate?

If it does NOT die completely, my money would still be with one of the stick coils.

You have the twin spark motor.  All 4 plugs fire at low rpm.  Under hard acceleration or anything above around 80km/h, the lower plugs stop firing.  Then only the top plugs fire.  In the event of one stick coil being faulty, the motor will then only run on 1 cylinder.

To find out which cylinder is giving the problem, unplug either one of the stick coils.  (Just the 1)  Now take the bike for a ride.  Accelerate hard.  If there is no change in the symptom, you have unplugged the faulty one.  If the motor dies completely, you have unplugged the good one.  You now know which side to work with.

Check the little plugs where they plug into the stick coil.  These are known to break quite easily.  You can buy the plug with a short piece of the harness from BMW.  (Part No:  83 30 0 402 341)

If the RHS coil is the one giving trouble, also check the RHS lower mounting screw for the ABS pump.  I have had 2 bikes where that screw came out and chaffed the wiring harness (and the stick coil wiring)

[BeemerKOS]

Thank you for the information, I was not aware that the lower plugs stopped firing at higher RPM. Answering your question, the engine cuts out completely and only picks up again when the throttle is backed off. The engine picks up again then and runs perfectly normally and will accelerate with a more gentle throttle application.  Unfortunately the bike is SORNed at the moment and in the process of being put back together having changed the fuel filter and cleaned and reconnected all the fuel and breather pipes. (A bit of info for those other owners of oldish BMs where water that collects around the filler cap and then drains through the tank, the drain hose connections through the fuel pump mounting plate had corroded quite badly and blocked the drain hose. at that point.) Until I put it back on the road I can only carry out garage tests. I will post again when it is back on the road.