1999 FLHRP, stock with the Magneti Marelli EFI system. You could crank this bike right now and ride 500 miles without a problem. However, if you go into race mode and really get on it shifting it out, when the RPM's go above 5000 the bike will shut down, as if you turned the key off. The headlights and dash lights all stay on, so there is no loss of 12v power. There is not check engine light illuminated or no trouble codes, both current and historic. If you turn the switch off and count to 10, it will fire right back up and you can ride normally, you can even shift her out at 4k RPM with no problem. But, wind her past 5K and instant shutdown. I'm thinking it has to do with the rev limiter and the ECM is shutting down the system completely instead of the intermittent cutout you would normally experience. I know, don't ride like a bat out of hell. But, I can't convince the owner of the bike and would like to have an opinion on what the trouble is.

thanks, Stroker

 

We need to start narrowing things down and first we are going to use the tach as a diagnostic tool to try to help us determine if it is a spark or a fuel problem. This is a "process of elimination" to find out what the problem is not to get us closer to what the problem is.

Does your tach immediately go to zero RPM like a switch being turned off or slowly decreasing to zero in sync with the engine slowly decelerating to zero RPM when this happens? Leaving it in gear breifly when the engine turns off will help this diagnosis. If the tach needle immediately goes to zero it's pointing us to a spark problem. If it slowly decreases to zero in sync with engine deceleration, it's pointing us to a fuel problem.

Does this occur at both part or full throttle and at the same RPM each time? Example, if it occurs at the same RPM at both part and full throttle, it points us to a spark problem.

 

Thanks for your help Gear Grinder. I just warmed the bike up and took if for another test ride. I was in second gear and gradually increased the rpm's, as soon as I hit 5200 the bike shut down and the tach dropped immediately. I hit the starter button while coasting down and the engine turned over but, it wouldn't start. I stopped the bike, turned off the dash ignition, counted to 10, hit the switch , fuel pump came on, hit the start button and it fired right up. Ran great, no misses, no hesitation, no trouble codes. Then I shifted up to 4th gear, increased rpm's an at 5200 same thing. So, in 2nd gear I was at half throttle and 4th full throttle. Throttle position didnt matter. 5200 rpm's is when she shuts down.
I'm not sure where the rev. limiter kicks in on this bike. But, I'm thinking that is where the problem is. I also did a data monitor on my scanalizer and all sensors were within range from a cold start to 274 degrees F.

Stroker

 

Your tests, I feel, eliminate the posibility of it being a fuel related problem. I do not think it is rev limiter related either because the ECM shuts down the fuel injectors, not spark. Thus, your tach needle would not instantly go to zero if it were rev limiter related.

It appears to be ignition related, the ignition module is guess #1 and the ECM #2. Do you have any real good buddies that you could borrow a Magneti Marelli module from? Putting the bike on a dyno and doing more trouble shooting would eliminate the guess work, possibly preventing the aquisition of some costly parts.

Another possibility, guess #3, is the crank sensor located on the front of your engine near the oil filter, the sensor that we have to be careful not to break with the oil filter wrench. Even though I put this 3rd on my list of possibilities, it is the easiest to get to and probably the least expensive to try, thus the first thing I would replace.

Good luck, keep us informed on your issue.

 

The bike did have a trouble code with 7 trips for the crank sensor. So I replaced that before riding, no more trouble code, but the cut out problem was still there. I didn't realize the rev limiter cut out the injectors and not the ignition. So I agree with you that it must be ignition/ECU related. I suggested to the owner that the bike needed to be put on a dyno , with the data monitored , so it could be diagnosed. Your right, replacing modules is expensive guess work. The owners said " I'll just keep it below 5200 rpm " Hopefully I can convince him to pursue the problem. I am very curious on this one. Thanks again for you help and I will update you when I can.

Stroker