Hi guys,

Just got an F4i, and when I purchased it the bike seemed to be running fine, no misses, etc. A day later I took it out to ride and it started fine and ran fine for about 15 minutes. Then, it started to miss when running without load on the engine (not accelerating or decelerating). I took it home and it sat for about an hour. When I went to start it up again, it didn't want to start, and only did so after giving it a little throttle for a few seconds. When it started, it was missing badly.

The bike has a K&N filter, M4 exhaust, and a power commander. I loaded the zero map on the power commander and things just got worse. There is an extreme miss all of the time (seems to not even be firing on one or two cylinders), it also smokes exhaust wet with fuel.

I took the plugs out and cylinders 2 and 3 the plugs were wet with fuel (not firing). It just had new plugs put on it before I bought it, so before I waste $85 to get new plugs I would like to know what caused these to go bad in the first place.

If anyone has any ideas that would be great, and sorry for the long post.

Thanks,

Jesse

 

Fuel pressure regulator

 

So if the fuel pressure regulator were bad, that would cause it to put too much fuel into the mix and run rich, thus fouling the plugs?

 

In the middle two cylinders, yes. The diaphragm simply broke allowing fuel into the vacuum line. That vacuum line comes directly from the middle cylinders. It a common problem with f4i's.

 

My bike was missing and running rich also. it all went away when i did the FPR and new plugs.