I had the petrol cap up today while the bike was running this afternoon and noticed fuel was spraying around the top of the tank. I assumed it must be a split pipe inside the tank. I removed the fuel pump and inspected all the pipes - no splits that I could see. Tightened all the clips and refitted. Still spraying! Any ideas? Getting grumpy with bloody bikes!
Someone on the BMW K100 forum did the same and complained that there must be something wrong. A few other owners ran their engine with the filler open and found that they were all the same. The solution is to not run the engine with the fuel filler cap open as it was never designed to work like that.
It's normal, the fuel pump runs flat out all the time and the fuel pressure regulator just dumps any excess back into the tank, at idle there's a lot of excess.
