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161 Posts
Lol, all that brain power just to unplug and reset the ecu! Glad you got it working again...
radiator fan will not shut off??
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12,056 Posts
It will be back.
Unhooking my ECU used to mysteriously repair my issues for a while too.
This action resets the ECU I guess, but does not exactly fix the fault inside the ECU which eventually returns.
Once mine would do nothing when I pushed the start button. I crawled all over the whole system and could find absolutely nothing wrong. I then decided to unhook the ECU for a few minutes... and when I hooked it back up, it fired right up like nothing ever happened.
But then randomly when I would let out of the gas, the engine would just shut off.
That is when I replaced it with a Procom ECU.
Unhooking my ECU used to mysteriously repair my issues for a while too.
This action resets the ECU I guess, but does not exactly fix the fault inside the ECU which eventually returns.
Once mine would do nothing when I pushed the start button. I crawled all over the whole system and could find absolutely nothing wrong. I then decided to unhook the ECU for a few minutes... and when I hooked it back up, it fired right up like nothing ever happened.
But then randomly when I would let out of the gas, the engine would just shut off.
That is when I replaced it with a Procom ECU.
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9,976 Posts
I agree with Duster, A problem doesn't fix itself, especially the Kawi ECU....
So prepare for it to happen again in the near future....
So prepare for it to happen again in the near future....
Hey duster I second what ol boy says your def a genius when it comes to tips, so at that I am having a problem with my fan as well. It wont come on at all. Left to idle for 15 mins after putting new yoshi rs 2 exhaust on, come back to it 15 mins later and head pipe is dark blue and purple! I was pissed. So i checked the fuse, it was good, pulled relay and tested, it was good as well. Any suggestions? Talked to a friend he said to check the radiator switch and see if its good and if not that it would be the fan motor. any Ideas would be greatly appreciated. Thanks bro
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12,056 Posts
Got your PM... Simple test...
Unplug your water temp sensor... on the back of the jug under the throttle body...
Fan should run continuous while unplugged if it is operational and you have the stock ECU.
If not we are going to have to check a bit more.
Where you located in the world?
Unplug your water temp sensor... on the back of the jug under the throttle body...
Fan should run continuous while unplugged if it is operational and you have the stock ECU.
If not we are going to have to check a bit more.
Where you located in the world?
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9,976 Posts
I would suspect a bad water temp sensor or ECU or Both...
There's a test to test the water temp sensor in the manual...
??? Is your water temp/F.I dash light "on"
Or replace it for it cost around $40.00...ECU $300.00
2008 Kawasaki KSF450B8FA (KFX450R) Parts, 2008 Kawasaki KSF450B8FA (KFX450R) OEM Parts - BikeBandit.com
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12,056 Posts
Water temp sensor is bad I'd say.
Replace that joker for the lesser price before assuming anything about the ECU.
Forget the test for the sensor in the manual... it's pretty worthless I figured out after a lot of hair pulling. You kind of have to use that data to formulate some useful tests from and most of them need doing at 32F.
Mine tested OK per the manual more times than not, but I finally figured out it was bad and telling the ECU the temp was a good 40 degrees hotter than it really was. So it would not start cold hardly at all due to that.
Install a water temp sensor and see what happens.
The ECU certainly is doing it's default activity and activating the fan due to 0v going to the ECU... this is a failsafe in case the sensor goes bad the opposite way yours has, or if the wires get broken.
Your sensor is likely just telling the ECU the water temp is much cooler than it is.
Replace that joker for the lesser price before assuming anything about the ECU.
Forget the test for the sensor in the manual... it's pretty worthless I figured out after a lot of hair pulling. You kind of have to use that data to formulate some useful tests from and most of them need doing at 32F.
Mine tested OK per the manual more times than not, but I finally figured out it was bad and telling the ECU the temp was a good 40 degrees hotter than it really was. So it would not start cold hardly at all due to that.
Install a water temp sensor and see what happens.
The ECU certainly is doing it's default activity and activating the fan due to 0v going to the ECU... this is a failsafe in case the sensor goes bad the opposite way yours has, or if the wires get broken.
Your sensor is likely just telling the ECU the water temp is much cooler than it is.
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12,056 Posts
Mine was bad and never turned the light on. Truth of the matter is the inside of the sensor has to fry into, or your wire has to get damaged or disconnected to make the EFI light come on for a water temp sensor issue. Wiring short or open is all it codes.
Kawi dealer or an online OEM parts source is the place to get the sensor.
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9,976 Posts
Yea! What Duster said, replace the temp sensor first and Try it...
If that doesn't do it, It will at least narrow down the source of your problem...
Then you can focus on the ECU....
If that doesn't do it, It will at least narrow down the source of your problem...
Then you can focus on the ECU....
Duster: my bike did what you described yesterday... Fan stopped working somewhere in the first lap(big water hole) an I overheated. Radiator boiled over and I shut her down. Then I essentially gave up onthe race but proceeded to get my money's worth and ride the course hard but not over do it or get in the way.
I got stopped at a bottleneck and heated her up again and then noticed the bike not wanting to stay running/idle the same. It died on a few down hills and then finally died in a valley and wouldn't restart. Walked up the hill and watched some other guys for a while then went back down and as soon as I hit the starter button it fired immediately... Ill probably tear it apart this week for multiple reasons, but definitely figuring that issue out. The fan makes a huge difference on these bikes!
I got stopped at a bottleneck and heated her up again and then noticed the bike not wanting to stay running/idle the same. It died on a few down hills and then finally died in a valley and wouldn't restart. Walked up the hill and watched some other guys for a while then went back down and as soon as I hit the starter button it fired immediately... Ill probably tear it apart this week for multiple reasons, but definitely figuring that issue out. The fan makes a huge difference on these bikes!
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6 Posts
just wanted to say ive got around 50 hours more on the 450 since my unplugging everything, and then plugging all back up, all is still well.
Similar problems here
Duster
I have similar problems on a machine i just bought used.
fan has never come on after 2 rides, last ride it overheated and light came on. i found the fuse blown. replaced it and no luck.
i have checked everything and replaced the water temp sensor and ECU with a procom and still no luck.
the only way i can get the fan to run is to short the pink/blue to ground at the relay connection and the fan comes right on.
the relay tests good but i have not replaced it.
any ideas? i'm just totally frustrated at this point.
Duster
I have similar problems on a machine i just bought used.
fan has never come on after 2 rides, last ride it overheated and light came on. i found the fuse blown. replaced it and no luck.
i have checked everything and replaced the water temp sensor and ECU with a procom and still no luck.
the only way i can get the fan to run is to short the pink/blue to ground at the relay connection and the fan comes right on.
the relay tests good but i have not replaced it.
any ideas? i'm just totally frustrated at this point.
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12,056 Posts
Sounds like a bad relay (not closing inside). Try swapping it with one of the relays that has a brown wire running into it.
This will allow you to test before buying.
Just depending on which one you use, you will loose the ability to start in neutral without pulling the clutch in... or the ability to start in gear with the clutch pulled.
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1 Posts
I’m having the same problem but have a procom ECU, setting 5.
I noticed when unplug the ECU and the problem will go away( the fan will turn off , and run fine) but after a while it’ll just sometimes kick on when I walk away from the bike.
What are you guys doing for a permanent fix? Can you wire a on and off switch to the fan where the ECU send signal to the fan?
I noticed when unplug the ECU and the problem will go away( the fan will turn off , and run fine) but after a while it’ll just sometimes kick on when I walk away from the bike.
What are you guys doing for a permanent fix? Can you wire a on and off switch to the fan where the ECU send signal to the fan?
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