My Fatboy started running like crap (sputtering, cutting out etc) sporadically under a load about 2 months after installing a power commander 3. I had it tuned at an authorized Dynojet dealer, and gained 20 horsepower. It seemed to only occur when it was real hot outside. I took it back to the tuner, and they couldn't make the problem happen while riding or on the dyno,

I got it home, and it started up again doing the same thing. I have changed plugs, air cleaner, and just recently the engine temperature sensor, all to no avail. Now it is really cool outside and it started doing the same thing after riding about 10 minutes. I am getting really frustrated.

I am thinking about the crank position sensor but hate to just keep throwing parts at it! Any suggestions? Thanks

 

Won't hurt to pull it out, post a pic and let's take a look at it. They are magnetic and can collect stuff; enough stuff and the don't read well. If they get bad enough, you will lose all spark. Worst thing that can happen is that you eliminate it as the source of the problem.

 

I went to pull it off and noticed the wire going to it was somewhat jicky....frayed and possibly shorting out. I taped it up with electrical tape and so far no problem...going to give it a bit and see if it stays running good. If so I will probably go ahead and replace the unit. Haven't read the manual yet (i know) but how does the crankshaft sensor come out?

 

Best if you get the service manual. The sensor is held in with a single bolt and in it's own harness. You cannot just buy the sensor; it comes connected to wires that run through the same harness as the oil pressure switch and oil pressure sender. You can cut the wires on the sender end of the old harness, remove the sender from the new harness and splice in on to the old wires, or try to pull the CPS wires out of the harness and pull the new one through (PITA), or you can run the new CPS wires outside the harness.

If you have temporarily solved the problem and it is the CPS, better fix it permanently or you could find yourself stranded. A lot of guys carry a new one in their tool kit, just in case.

 

Good Advice ..

 

Hey Jay,
I am looking for a '99 or '00 FXR4 for a project bike. Don't care about the condition of the motor as I plan to yank it and replace it with an S&S 106 or 111; forget which one. If you run across another one, let me know.

 

Will do djl ...

 

Well I am an idiot.....I have pulled the CPS before and again it had no shavings on it. The frayed wires I saw were from the other side of the oil filter...but it is still running crappy and it is cool out now. Again, it seems to be real sporadic, but the one consistent is it doesn't happen until I have been riding for a while, and it gets to operating temperature. I am going to replace the CPS and see if that helps...will keep posting

 

OK I am going to buy a new CPS part #32707-01C ($54.70) and swap it out....more research shows this thing gets jicky with heat and that fits the bill

 

Let us know how that works out.