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Discussion Starter #1 (Edited)
Hi there,

I have an 04 CBR600RR and I was riding it a bit hard on some twisties on a mountain road and she just suddenly lost power similar to the kill switch being set to off position while riding. I pulled over checked all fuses and ended up having to put the bike on a trailer and tow it home. I did have to order a new battery as the old one was pretty much dead from trying to get it to start. Battery also wouldn't hold a charge.

First thing I did was check fuses and they all were good, then I swapped all the relays and still it didn't want to start. After some voltage readings I discovered the fuel cut relay wasn't getting ground signal from the ECU through the brown/black wire. So I researched and found a wiring diagram to help me out with the wiring.

The fuel pump runs if direct power is supplied to it. Also jumped the fuel cut and starter relay and the fuel pump primed but didn't start

I called my friend to have my ECU tested on his bike and his bike started without any hesitation. Next thing I checked was the zener diode which I found out by reading forums. I am getting 9 volts on the zener diode in the ignition through the pink wire.

I checked the yellow box under the fuel tank and they all have continuity. Also the FI fuse near the battery is good but I changed it out just to be sure.

To test the BAS I turned the ignition to on position with the BAS removed from its mounting point and turned it sideways to see if it would activate the start relay and both left and right caused the relay to click which eliminated the BAS (Also by reading forums)

The kill switch activates the start relay and also cuts out the headlights when I try to start the bike.

I am stumped and my bike has been down for just over 4 months now. Any input would be greatly appreciated.

Sorry for the long post but I hope I got everything written down.

Thank you everybody.
 

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Hey Mate,

Try bypassing the BAS sensor to see if thats faulty..

By the sounds of it there is something preventing the fuel pump priming

Ways i got it sorted or there was issues with is the follow

- BAS Sensor
- Hiss Security System
- Fuses
- Faulty Pump
- Faulty Kill Switch
 

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Discussion Starter #3
Hey Mate,

Try bypassing the BAS sensor to see if thats faulty..

By the sounds of it there is something preventing the fuel pump priming

Ways i got it sorted or there was issues with is the follow

- BAS Sensor
- Hiss Security System
- Fuses
- Faulty Pump
- Faulty Kill Switch

Hey Mick,

Thank you for your reply.

I have the U.S version of the CBR so I don't think there's the HISS system installed on my bike. The BAS tested out good when bypassed.

All fuses, relays, kill switch, BAS, fuel pump (direct power from battery) are good, zener diode also. I am not getting spark or power to fuel pump through the wiring system.

I did more research on forums and a friend of mine said it could be the pulsar coil trigger. I ordered a used one on ebay and will find out if its the culprit.

Will keep you updated on progress.

Thanks again for your reply
 

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Does the fuel cut relay and engine stop relay click over when you switch the bike on?
 

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Discussion Starter #5
The engine stop relay clicks, however I'm not getting the ground signal from the ECM to the fuel cut relay. We switched relays and same problem.

I had my ECM tested on a friends bike and his bike started up fine.


(Update)
My friend and I changed out the Pulser coil sensor and same problem. We jumped the start relay to the fuel relay and got the pump to prime, went to start it and it didn't fire up.

At this point I'm stumped. I think its something to do with electrical wiring.



Does the fuel cut relay and engine stop relay click over when you switch the bike on?
 

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If you know your not getting a ground to the relay than maybe the wire is broke somewhere. Have you tried just using a piece of wire to make a temporary ground from ecm to the relay?
 

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Discussion Starter #7
I did a continuity test on the br/bl wire from the ECU harness to the fuel relay and it tested good. Also did tests to the fuel pump and ground connections. All tested good. We bypassed the fuel relay ground to the brown/black and that's how we got the fuel pump to prime.

My friend said it could also be the cam position sensor that might be bad but I don't know if it would prevent spark and fuel pump from working. I'll continue searching on more forums for solutions.

My very last option is to take it to a shop but I'd rather not risk paying a massive bill just to get it running.

Thank you for your input




If you know your not getting a ground to the relay than maybe the wire is broke somewhere. Have you tried just using a piece of wire to make a temporary ground from ecm to the relay?
 

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Discussion Starter #9
The fuel tank wasn't raised or repositioned. It happened while I was riding, just suddenly lost engine power at roughly 65mph. It didn't backfire, or sputter and I tried to bump start it but while I was coasting to a stop but nothing. It seems to be a common problem with CBR's. I might just get a used cam position sensor on Ebay since its about a $50 part.



Out of curiosity did you raise the tank soon before this problem started? It may just be a kinked breather hose causing vapor lock in the tank.
 

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FWIW. I had a similar problem when I first started riding the track one day. Just cut off and wouldn't start. Bypass the kickstand switch, never happened again.
 

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Discussion Starter #16
We ruled out the kickstand by bypassing it. Also it would crank but not start in neutral.

Thanks guys I appreciate the feedback



FWIW. I had a similar problem when I first started riding the track one day. Just cut off and wouldn't start. Bypass the kickstand switch, never happened again.
 

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Check your grounds, then continuity test from the ECU to the relay.
 

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If you haven't swapped your relays testing that out, can you test how many volts you have entering in pin 29 (grey plug), a common problem that people getting stuck with is the zener diode.
 

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The diode shouldn't fail, usually when they do it's because something has taken it out.

More likely an issue with wiring, which would of course include the one you're talking about...
 

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Discussion Starter #20
I forgot to mention its a new ignition because I lost the only key I had when the bike was towed home. What luck yah. I also get 9v on the pink wire from the ignition.

The only other culprit is wiring. Besides the yellow box under the seat, and the left side of the bike next to the relays are there any other ground points that you know of? I did continuity tests on those location and also from the relay to the negative of the battery. THey all tested good. I got near 0 ohms reading




The diode shouldn't fail, usually when they do it's because something has taken it out.

More likely an issue with wiring, which would of course include the one you're talking about...
 
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