RPM's drop to 0 when I cruise at around 4700 RPM's?

[Stoney McSloth]

Ok first off I have a 05 LE and my problem just started about a week ago while I was out riding. What happens is if I cruise around (doesn't matter what gear it's in) but at right around 4700 rpm's the bike will drop to 0 rpm's loose all power for a couple seconds and then come right back up to where it was. It doesn't happen all the time but it has happened enough times to make me start to worry. Now if I keep it below 4500 rpm's or above 5000 rpm's it doesn't do it at all, it runs normal. But as soon as I start cruising around that 4700 mark it happens again. Almost like the bike's fuel has been shut off, the tach drops to 0 and starts to decelerate but it only lasts like I said for a couple of seconds and then the rpm's return to normal and the bike acts normal. Has anyone had this problem before with a specific rpm range? And would it be the fuel pump, ECU or something else? What I can't understand is why it only does it around 4700 rpm's and not anything else. Any answers would be helpful. Thanks in Advance.

 

[The Big Red One]

No thats not a typical fuel pump issue....sounds electrical. Have you added or changed anything electrical on the bike lately? Are your battery leads tight and clean? Battery holding a good charge and starting the bike up quick? And be sure the battery ground is tight and clean at both ends as well. Same with the positive. Then check your kickstand switch.

It could also be a loose connection somewhere. First check any connections you've possibly messed with lately, then start with the ecu connections and move on to anything you can easily see and reach and make sure they're plugged in tight. Also any bare wires shorting to the frame could cause that.

 

[Stoney McSloth]

the only thing I have added lately is a USB plug I got from Pashnit awhile back. The bike starts right up and runs fine until i cruise around the 4700 rpm's. I've checked all the connections/fuses and so forth. And that's the thing if I stay below 4500 rpm's or above 5000 rpm's it has never done it. It only happens around the 4700 rpm range and it only happens for acouple of seconds, it's not like it happens and doesn't come back. I'm just wondering why it is only doing it around 4700 rpms and not any other rpm range.

 

[The Big Red One]

How is the usb plug hooked up?

 

[dadofthree]

At that RPM range you might be at the heaviest vibration point on the bike and I was thinking electrical connection as well. Best of luck.

 

[Stoney McSloth]

USB is hooked up like the instructions said direct to battery with the included fuse. And if it was a connection I would think it would do it at other points in time or even going over rough roads or bumps. I don't think it's the battery because when it happens the gauge lights and the head light doesn't dim it stays constant. And the bike starts right up with no hesitation.

 

[mikbusa]

Are you sure it's rpm related, and not throttle position related? Sounds like a bad TPS.

 

[lil charlie]

I was also thinking TPS....

 

[Stoney McSloth]

I did a search of the forum and really couldn't find any previous threads on the TPS. Is there any way to check the TPS from idle to WOT? To see if it's the problem or not.

 

[Stoney McSloth]

Well I think I found the problem I was having on the ride home last night when the bike cut off and the smoke started to come up around me. And of course this happens on a back country road where I don't have any cell signal (I really hate T-mobile in NY). So I walk to where I get cell signal and get picked up after pushing the bike to a safe location for the night. This morning put the bike on the trailer and head back to my buddies garage, pull the bike in and start taking off the tail section. And this is what I find. Seems that I caught the rectifier on fire on my trip home. Luckily besides melting some of the tail light wires there is no other damage to the bike that I know of so far. I'm just really hoping it didn't do anything to the ECU when it caught fire and wires started to combine together.