BMW K bikes (Bricks)

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1Back to top Go down   Electrical gremlin Empty Electrical gremlin on Wed Sep 09, 2020 5:43 pm

davemadsen

davemadsen
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My 1987 K100RT has been a reliable and trouble free bike for years and many, many miles and I try to do my part in keeping the maintenance current to include keeping most of the switches clean, corrosion free, and slathered in dielectric grease.

Recently the bike has taken to going dead as it idles or, more commonly, as I come to a stop. The engine doesn’t falter, it is as if I hit the kill switch. Up to this point this seems to be a typical short or poor ground (and either of these could in fact be the issue). But I want to mention a couple of things I noticed to aid one of you gurus towards pointing me in the right direction:

The problem occurs once in ever 20 or 30 stops
When the bike dies, the gear indicator goes blank - and then after 10 seconds or so, the indicator comes live and the bike will restart.
And today’s secret clue is this: the low fuel light comes on. The low fuel light has not worked in years and the tank was about 3/4 full (and verified by a fuel gauge and a recent receipt from Chevron).
During the last two occurrences, I refrained from panicking and flipping switches and pushing buttons, rather just I waited ten seconds or so until the gear indicator came live, at which time the bike restarted and I continued on my way. It was during these panick-less stops that I noticed the low fuel light burning. 

The purpose of this post is hopefully get advise from you on where to start, as opposed to spending my time in a direction which doesn’t make sense.

Dave


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Dave
    

2Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin on Wed Sep 09, 2020 7:54 pm

Arlina

Arlina
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Check the startermotor brushes, should be longer than 7mm.
Place some new ones and I guess the problem should be over.
Leaves you as gremlin as you post this in "buy and sell" Razz


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Electrical gremlin Eu-log10  K1100RS/LT - R1200RT - R1100RS (RIP) - Cagiva SST 350 Ala Verde - K75LT project
    

3Back to top Go down   Electrical gremlin Empty Gremlin on Wed Sep 09, 2020 11:13 pm

daveyson

daveyson
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I'm reaching, but since the problem has suddenly started and the fuel light has also suddenly started, if unplugging the white wire to the fuel light fixes the problem, that might be a place to look.

It's three quarters full because you looked in the tank,  or at the fuel gauge or both? Maybe alternator brushes wanna look see too.

Wiggle some wires, like say at the instrument cluster or tank, to see if it affects the gear indicator, fuel level light or something.

How's the previous momentary miss with turn signal problem going?


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

4Back to top Go down   Electrical gremlin Empty Gremlin on Thu Sep 10, 2020 4:19 pm

daveyson

daveyson
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Actually, ignore my previous post until you try this; clean the socket for fuse one (top fuse) and replace it with a new fuse, even if it looks good, and see if that makes a difference. It's probably the quickest, easiest check. Probably the cheapest, weakest link in the chain too.

Then do the other fuses. It's a good thing to do, even if you don't have problems.


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

5Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin on Thu Sep 10, 2020 6:46 pm

davemadsen

davemadsen
active member
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Okay. I have a couple of “to dos” and I will report back.

Fuel level was verified...about 3/4 full.

On the turn signal intermittent problem. I have ordered another flasher relay to see if that may be the issue.


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Dave
    

6Back to top Go down   Electrical gremlin Empty Gremlins on Thu Sep 10, 2020 7:13 pm

daveyson

daveyson
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Life time member
I was thinking fuse one might be the cause of the turn signal problem too.


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

7Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin on Fri Sep 11, 2020 12:47 pm

davemadsen

davemadsen
active member
active member
@Arlina wrote:Check the startermotor brushes, should be longer than 7mm.
Place some new ones and I guess the problem should be over.
Leaves you as gremlin as you post this in "buy and sell" Razz
On the chance that I just might learn something, why would the condition of the starter motor brushes have something to do with the bike dying?


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Dave
    

8Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin on Fri Sep 11, 2020 6:55 pm

moriarti

moriarti
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On this forum iv read of a few Strange hiccups being traced to the starter,how many Km/years is it since it was serviced.Worth a look and you might learn something you can share with us .


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1984 k100 rs red/black VIN  0004449
    

9Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin on Fri Sep 11, 2020 9:44 pm

Dai

Dai
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Life time member
Because a large amount of the electrical system earths through the starter motor brushes and the starter motor coils. Is why the load shed relay drops out when you hit the starter button and turns the lights and other bits off. Normally pin 85 on the load shed earths through the aforesaid starter bits but when you hit the button, the starter circuit back-feeds 12v to pin 85 and the relay drops out.

Not a terribly good idea on BMW's part but then who knows how much schnapps Hans drank before he designed that system.


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'83 K100 upgraded to K100RS spec, '87 K100RT
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'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California
    

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