Join Date: May 2019
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2011 BF 750 Crankshaft Position Sensor - Help
I finally got my 2011 BF 750 to at least fire up and idle - finally!
It won't run if I leave the Air Idle Control Valve (sometimes called the idle speed control valve) line connected (vacuum lines) to the forward cylinder. I can keep the rear cylinder line connected and it will start. And when I say start I mean like a cranky cold blooded machine. The other item of note with the air / speed control valve is that it gets really hot after a few minutes. So hot that if I touch it for more than a second and I'd burn my finger. Some say this is normal with their unit. True???
Once idling the front cylinder will occasionally backfire but not bad. It isn't a loud pop out the tailpipe but rather a muffled pop inside the forward cylinder throttle body. I can see a flash of fire around the butterfly valve as it idles. Doesn't die but will backfire every 5-10 seconds. If I give it any amount of throttle it dies.
My research points to the Crankshaft Position Sensor however I have tested it twice now. Peak voltage is 3.3V, and Ohms at 481 both of which the manual says is within range.
The other thing I noticed is that when it first begins to idle it seems to burn the proper amounts of fuel but after a few seconds and some clicks from the bike it spews out blue smoke and smells heavy of gasoline as it chugs and sputters.
Fuel pressure is nominal 44psi. Air temperature sensor, air pressure sensor, throttle position sensor have all tested good. Injectors are new.
Do I replace the CPS even though it tested good?
Any advice is appreciated.