BMW K bikes (Bricks)


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mateng0

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Please help someone? I'm scratching my head as to what is wrong with the starter circuit on my K100.
First off let me tell you that the bike has been stored outside in all weathers for the past 6 years without being started. I bought the bike last week with the intention to bring it back to its former glory.
It has 19000 miles and I'm the second owner.
I've fitted a new battery and get all the lights on the dash board come on. The lights and the horn don't seem to work and also the indicator lights seem to default to a hazard warning light setting. When I hit the start button the fuel pump relay clicks on and so does the start relay also there is a click in the fuel tank which I presume is the fuel pump kicking in. There is no action at the starter motor though. I have pulled the starter motor out and it seems to be ok although I'm going to test this away from the bike in a moment.
Any ideas Guys???

    

phil_mars

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Just about guarantee it is the starter brushes as it acts as the earth for the load shed relay so that is the first thing I would check.

Just take the starter out and give it a good clean and new brushes if required and see how you go.


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Phil
    

mateng0

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Genius Phil. One of the brushes in the starter motor was sticking so I cleaned it all up and its turning over beautifully now. The lights and the horn are also working.
Next step now is to check the condition of the fuel pump as it doesn't seem to be making a great deal of noise when the ignition is switched on.

Thanks very much for your help

Mat

    

phil_mars

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I appreciate the comment but most of my knowledge is acquired from this and other forums.
The main thing is that it is now starting. As for the fuel pump depending on the year you will only hear it going when the starter is pressed. It does not come on with the ignition although the 16V may be different and generally it is reasonably quiet if the tank is full.
Definitely worth removing though just to make sure all is well inside the tank as the rubber mount for the pump may have turned into something unpleasant.


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Regards,
Phil
    

Crazy Frog

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A quick push on the starter button should energize the fuel pump. You will hear the buzz inside the tank.
The pump should turn as long as the engine is cranking or the starter button is depressed.
If the engine is not cranking, the pump will stop as soon as you depress the starter button.

Here is the electrical starting sequence when you push the starter button:

The starter relay and Fuel Injection relay close, Hall sensors get power.
The FI relay energizes (+) the fuel pump, the idle switch, the injectors and the air flow meter.
The Jetronic receives (pin #4) the signal that the engine is starting and it sets itself on starting mode (enriching the air/fuel mixture)
Electronic ignition module pin # 9-10-14 send power to the ignition coil
Electronic ignition module pin #8 send engine rpm info to pin #1 of FI computer
Electronic ignition module pin #7 send ground to the coil of the FI relay as soon as the starter switch is depressed. The ground will stay on after the starter switch is released as long as the Electronic ignition module receives a signal from the Hall sensors.


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K100LT Can't get the starter turning!! Frog15K100LT Can't get the starter turning!! Logo2101986 k75, 1985 K100rt, 1985 K100rt/EML GT2 sidecar, 1999 K1200lt/Hannigan Astro Sport sidecar.
    

blaKey

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See Mat, simple isn't it...


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Neil
K100RS 1986 RED!

Dress for the ride and the potential slide.
    

K-BIKE

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As Phil noted on the 16 valve the fuel pump spins up as soon as you turn the key on.
Regards,
K-BIKE

    

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