K11 Owners Group

[rgscomp]

Hi,

Have seen a few posts about high fuel consumption so am posting the resolution to my problem.

This was a sudden onset problem. Travelling from London->Newcastle on a Friday was 45-48mpg. The return on the Monday was 30-35mpg with lots of backfiring on the overrun.

All four plugs were sooty black, so have been tracking down this overfuelling for several weeks now.
Changed plugs, air filter.
I checked the coolant and air sensors but readings hot/cold were OK.
Secondhand ECU from Ebay gave same fault but eliminated the pricey part.
Replaced fuel regulator with aftermarket adjustable one, and by turning down the fuel pressure a bit was able to get consumption up to 40mpg. This was clearly not the actual problem.

On Sunday, I pulled the LHS fairing off and started prodding and wiggling the connections to the injectors. Wiggling the number 1 cylinder injector and it's connector showed up the fault. The engine would run really rough and then briefly run smoothly as the connector was moved. It fact, I even unplugged it at one point with no change to the way the engine was running at tickover.

I pulled the fuel rail and swapped the injector to cylinder 2 to eliminate the cabling, and the fault moved to cylinder 2.

One secondhand injector from Motobins later, and the London-Newcastle run yesterday was at 48mpg. No backfiring. Also, the end of the silencer had been covered in sooty black deposits and that has gone too.

Not sure how one injector caused all four cylinders to run very rich, and that is why I left them to last as I assumed it was a problem affecting all four cylinders at the same time.

Anyway, it's fixed and maybe this will help someone else....

[tmoons]

[rgscomp]

It's a 97 model without the O2 sensor.
Now I know what the problem was, I'm guessing that the ECU was trying to compensate for the low/uneven tickover by pushing more fuel through the engine.
Higher revs it was probably me having the throttle open further, again to compensate for a missing cylinder..