Engine cut out

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Uber09
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Engine cut out

Post by Uber09 » Tue Feb 21, 2017 2:40 pm

Hi...my engine switches off when temperature guage reaches the halfway mark. Can a fan switch thats not operating properly cause the engine to switch off??

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Ozzibiker
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Re: Engine cut out

Post by Ozzibiker » Wed Feb 22, 2017 10:14 am

My fan switches on when the needle is vertical. About 100 - 110°C. It sounds like you're heading in the right direction. I'll have a look at the wiring diagram later. Maybe others will know more.

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Ozzibiker
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Re: Engine cut out

Post by Ozzibiker » Wed Feb 22, 2017 10:16 am

Oops. Superfour. Not a VFR. Your situation seems odd, but possible. Will look at manual anyway.

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Uber09
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Re: Engine cut out

Post by Uber09 » Wed Feb 22, 2017 10:41 am

Thanks ...this is for a cb400sf

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Ozzibiker
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Re: Engine cut out

Post by Ozzibiker » Thu Feb 23, 2017 1:30 am

Others may know better, but I can't see how the engine would stop because of the fan apart from a short circuit. I can see no direct link between the ignition and the fan wires.

However, it seems the fan turns on when the wire to the thermostat switch is grounded. So maybe you can check if that is the cause of your problem.

While the engine is running, if you pull the connector off the thermostat switch (I assume you can), and put it to a ground (maybe just touch the frame somewhere not painted) then the bike should stop if that is the cause. This may cause the ignition to be grounded somehow.

I got a look at the manual here:
https://skydrive.live.com/?cid=A057E...814610E8%21138
But the image is a bit crappy. Diagram p129, 130.
Fan and thermostat features are at the bottom middle.

Image

iansoady
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Re: Engine cut out

Post by iansoady » Thu Feb 23, 2017 3:14 pm

I could see how it might blow a fuse if (for example) the motor windings were shorted but then it wouldn't start again.

I don't think our bikes are sophisticated enough to have controlled shut-down in these circumstances.

I'd try Ozzibiker's suggestion and report back.

Uber09
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Re: Engine cut out

Post by Uber09 » Thu Feb 23, 2017 8:13 pm

Hi....I've removed the fan wire and earthed. The fan goes on. Which leads me to assumption that fan switch is problematic. Furthermore when bike cools down, it starts like normal. Upon reaching the halfway mark on temp gauge, it's starts to splatter and then switches off.

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Ozzibiker
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Re: Engine cut out

Post by Ozzibiker » Fri Feb 24, 2017 1:39 am

When you earth the fan wire does the engine turn off? If not, does the engine keep running with the fan on? If so the switch is the problem.

I don't have a manual with me now, but maybe there is an overheat switch and the engine is being switched off since the fan is not running and cooling the engine.

Where do you live? The VFR fan doesn't turn on unless riding slowly in summer. I'm surprised your fan is turning on if it's winter for you.

Ozzibiker
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Re: Engine cut out

Post by Ozzibiker » Sun Feb 26, 2017 7:16 am

As Iansoady said, there is no automatic engine shutdown due to high temperature.

The fan wiring seems quite independent of the rest of the system, so I don't know where a short could occur.

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