Electrical start up problems

[Francka]

2 weeks ago I was very lucky to take over a 1991 K75 RT with a side car.
A beautiful bike. I was aware of that there were some electrical issues on it. But by staring the engine the instructed way there was no problem.
The issue was that when hooking on the battery the fuel pump started to run. To stop it, the battery had to be disconnected. 
The other day I started to fault find on this problem. I think there must be something related to the fuel injection relay or the four-pin connector under the fuel tank.
Unfortunately something else occurred. When connecting the battery now, there are no ignition lights coming up on the instrument panels, and of course then there is neither any reaction when pushing the start button.
The gear is in the neutral position, and the butterfly (kill) switch is in the start position.
 When the key is in the off position, I can hear that there is something switching ( A relay maybe ?)
Any advice is welcomed.

[johnny]

greetings francka...

welcome to motobrick.com...

if your battery is good fully charged and hooked up properly... and no unskilled hands causing undisclosed whack...

01 - backspin starter maintenance...

02 - whack stuck starter relay...

try it and post up...

j o

[Francka]

Thanks a lot for the reply Johnny.

The battery is new, and have a green indication eye, showing it is good.
The issue actually happened during operating the start engine button, so i agree in a possible stucked starter relay. But I assume then that the starter motor would be running when battery was connected. Something is clicking when battery is hooked on, but it do not sounds like the starter motor. Anyway. I will try your advice`s, and post up.
Great site btw


francka 
 

[johnny]

greetings

the worlds foremost motobricker is near fredrikstad norway...

im not saying the starter is whack... just something i would do in attempt to avoid whack...

j o

[Francka]

Hi Johnny.

Followed your advice today, and.
Ignition lights came back in the instrument panels. So yes I believe it could have been a sucked starter relay. Thank you for the good advice.
I have a new one available, and will probably change it one of the coming days.
I mannaged also to start up the engine again, but with another battery (A high capacity car battery ) Every thing worked. I even managed to find out about the fuel pump that earlier was running continueously even with the ignition key in off position.   
However there are some issues that I do not clearly understand.
I can only crank and start the engine by using the additionally high capacity battery.
The new battery installed in the bike has a green indicator light showing it is OK. it measure 12,3 Volt. I did some measurements today, and measured the voltage over the battery when the ignition was turned on by the main key. It dropped down to 6 volt. (it is of coarse not possible to crank the motor by this low voltage) It is not an original BMW Battery, but it is new and shows that it is OK (20 Ah capacity)  I believe an original BMW battery is 25 Ah. 
Could it be that something on my bike is drawing to much power or is it just that the battery currently installed is not the right one to use. When using the high capacity battery in parallel with jumper cables. everything runs perfect.
Anyway, to be sure that the battery installed is fully charged, I will charge it. The indicator eye could by wrong. Or I will buy a new original BMW battery.       
   

[kioolt]

You're either drawing a lot of current or you have a bad battery. A good battery should not drop that much voltage with just the key on unless you have some unknown un-normal load. With the key on see if you get a very big spark when connecting or disconnecting the battery cable.   No need to purchase a BMW battery.  There's nothing special about them.  Just buy the correct rating battery for your bike.