I hope I explain this right but, I have an 04 Ultra Classic with the 95" upgrade, D&D Fat Cat exhaust and K&N air. The issue, sometimes the bike is hard to start. Happens when hot or cold but mostly when hot and shut off for only a couple of minutes. It will crank over but not fire off. When this happens, if I twist the throttle to almost wide open, it will fire up. When turning over, it will sometimes backfire through the throttle body but, not always. It has been suggested that it may be the crank position sensor. It has not thrown any codes when doing this. Is it possible that the crank position sensor is "going" bad? Am I looking in the wrong direction? Any help or advise is appreciated. Thanks

 

I've never heard of a crank sensor acting like that myself

 

I've seen CPS do strange things in cars/trucks. The purpose of the CPS is to send a trigger signal to the ignition circuit to fire the plugs, so yes, it's possible. Have you checked the connections for corrosion.

 

Yes, the connection was clean but, I brushed the contacts on the male side with a brass brush and used dielectric grease when I put it back together, no change.

 

The sensor itself is like a guitar pickup, its a coil around a polepiece. The flywheel has teeth around the edge, and when its spinning it generates a voltage in the sensor.

A manual will give what you should see reading an ohm meter across the coil, and an AC voltage you should see at certain RPMs.

Sensor is a simple beast, and its usually alive or dead, not often intermittent. Intermittent is most probably a bad connection somewhere else.

 

Try cleaning the sensor. It's right by the oil filter. One screw holds it in. Wipe it off with a clean rag and then check the rag for metal filings. If any metal is found then that was probably the problem.

Dan

 

In my experience, a bad crank sensor almost never throws a code; but, as Andrew said, it's usually either go or no go. Not intermittent. I'd look else where for your problem.

 

I did pull the sensor out and cleaned it. There was nothing on it but, wiped it off real good any way.

Is it possible that the Throttle Position Sensor could cause this? I'm at a loss.

 

I doubt its a crank sensor. easy to check. hook up your ohm meter, should read app 700-850 ohms. take a hair dryer and aim at sensor, on high. should hold reading after 15 seconds or so. If bad will go to infinity. Without seeing the bike, I would bet you are having a fuel pressure issue. Pressure is bleeding off somewhere. Good place is inside the tank, or possibly injector. Either hook up a pressure gauge and see if it holds at least 30lbs or try to figure out some way to watch system visually. Pull an injector and see if it dribbles. Throttle switch only tells ecu what position the throttle plate is at, and will not really effect a hard start. The fact that there is no codes sounds more like the fuel pressure issue. Let us know

 

Had this type of thing happen on my 07.......sometime is starts...sometimes it doesn't .......but when it DOES start, it happens like there was never anything wrong.......come to find out it was the IAC......Idle Air controller.....it''s just inside the throttle body at the 12 oclock position.....stuff a rag in the throttle body.....while the IGN ON and toggling the kill switch on and off......spray a cleaner up in there....gets real chitty from the oil mist being sucked in........i've had no prob since!!