Need Help FZ6R - Sudden ignition cut-out, won’t restart until cool

[Henrikdosvik2]

Hi all,

I’m having some trouble with my 2012 FZ6R, and I’m hoping someone here might have seen this before or have some ideas. The bike runs fine at first, but it suddenly cuts out completely, as if the ignition has been switched off. It happens very suddenly — no warning, no sputtering, just dead. I think it may be some electronics overheating as it cuts out more frequently on hot days. On cool days it may not stall out, btw I live in Norway so temperature varies from 10C-25C.

When it happens, I can’t restart it right away. If I wait about 30 minutes, it will start again, but it cuts out shortly. If I let it cool for a couple of hours, it starts and runs longer before it eventually stalls out.

Since the engine dies so suddenly, I’m thinking it’s probably an ignition issue rather than fuel. I know the bike has two ignition coils (it’s a wasted spark setup), so I would expect that if one coil failed, it would still run roughly on two cylinders. Instead, it just stops completely. That makes me think it could be something like the crankshaft position sensor (pickup coil), the ECU, or maybe a bad connection somewhere that’s sensitive to heat.

Usually there is no code in the diag mode, however one time it threw code 12 which relates to crank position sensor.

I haven’t checked for spark right after it dies yet, as its difficult as it cools before I have the time to dissasemble. I wanted to ask: has anyone experienced something like this on an FZ6R or similar Yamaha? Are there any common failure points I should be checking? I’d really appreciate it.

Thanks in advance for any suggestions!

 

[Gary in NJ]

My first thought are the coils. It would be worth a physical inspection to see if they have cracked (failed) as well as ohms check of the primary and secondaries. Coils usually show this cold/hot behavior when they fail.

 

[Henrikdosvik2]

Thanks for reply! I agree, it sound like coil, will check them when I have time. However don't you think it is weird that both would fail simultaneously?
At least that's what my local Yamaha dealer said.

I also disassembled the cover to look at and test the CPS and found that something has happened to it. See the attached picture.
However, I remember seeing this last year while adjusting the valves. But decided to leave it as it worked fine.

What do you think? It does not look good. But while measuring it is within spec.
I also tried to fix it by soldering, however I do not know if I did the best job, see the second picture.
Ordered a new CPS from ebay, slightly used but looks good. Will try to fit that one, if it still not good I will check coils.

 

[Gary in NJ]

You are correct, the hot/cold issue is also a failure mode of a CPS (I went through this on my Ducati). The CPS on the FZ6 is robust and is not a common failure point, however something has happened to yours (rodent?) that makes it suspect. Heck the coils to rule them out and install the eBay CPS…between the two you should have the problem resolved.

 

[Henrikdosvik2]

Alright! Will give an update when the new CPS is installed! Will also check coils if the weather get better, its currently raining a lot and I do not have a garage...

 

[Henrikdosvik2]

I received and installed the new sensor yesterday. While doing the swap, I measured the resistance of both the old and the new sensor. As shown in the picture, the original sensor is out of spec, while the replacement (from eBay) measures correctly.


I took the bike for a test ride, and everything seems to be working fine — no ignition cut-outs. That said, I still need to test it in warmer conditions to be sure, since both times the issue occurred it was on days above 20°C. According to the weather forecast, it might be a couple of weeks before we get those temperatures again.


As I mentioned in my last post, something has definitely caused damage to the original sensor. I’m not sure how it happened, but the bike was previously used by a driving school and has been dropped a few times. My guess is that the timing chain may have made contact with the sensor at some point.


I’ll keep riding it and will post an update once it’s been properly tested under warmer conditions.

 

[Gary in NJ]

Ambient temperature will not make much a difference once the bike is fully warmed up. I would declare the problem solved.