New member from Denmark

Just bought a bmw K100 RT from 1988.   

Runs fine but can suddenly come to a halt. After a while it can start again when it gets cold. Does anyone have a suggestion repair. I suspect that it could be bad fuel lines as it smells a lot of petrol most while driving and just afterwards

Could be a bad Hall Effect sensor.  They can act up when hot if they are about to fail.  Easy test is to start your bike cold and heat the hall sensor assembly gently with a hairdryer.  If the bike cuts out, you know this is the problem.

The Hall sensor assembly is under the square plate on the front right side of the engine.  Remove the six (or so) screws and the plate comes off, revealing the assembly.

Welcome to the forum. Sorry to see you have a problem with the K.

The Hall sensor is a likely possibility, most likely if it will start again from cold. Lot of posts on it here too.

Welcome to the forum. Welcome to BMW Hall sensors.  If they are bad which is very likely here is a link to a much cheaper alternative http://www.bbautomacao.com/home_hall_effect_sensor_cyhme56.html and  http://www.jaycar.com.au/productView.asp?ID=ZD1900  and I believe that Radio Shack will also have a listing.

Even cheaper................http://www.hallsensors.de/Hall-Vane.htm

Hej LPM

velkommen til. 

Hi and velcome ,you better listen to these guys ,they are ussually right  


k-rider

impressed    with this forum, it's great, reliable and fast, just like a K100   

Thanks for the fast dianogse. Will see if I can find the Hall Effect Vane Sensor on the bike and test it it as described.

maybe someone here who can guide me to locate this sensor. I am completely new to k100 repairs.

I'll give feed back when I've got it tested, so you can see if it was the right dianogse


But it sounds like a really good bids from experienced k100 owners.

many thanks for the quick response  

So you gotta just read it all, robmack from canada do also described how I find the sensor, wonderful and thank you again

The Hall sensor assembly is under the square plate on the front right side of the engine.  Remove the six (or so) screws and the plate comes off, revealing the assembly.


remove no. 6 and you will see the hall sensors

k-rider

This link could become useful, it's for a oilhead but the hall sensor is similar.

Hello again. 

I have now tested halls sensor up to 160 degrees. It worked as it should without grinding to a halt. Super I thought    as I drove.... but no on the way home from a trip to the port I wanted to look at a BMW RT 1100 at the motorcycle dealer, I parked my BMW K100RT, I looked at the lovely Rt 1100 he had for sale. Here, after a quarter of an hour would I start my k 100, but never got life in it.    I've now got it home and the only way I can get it to turn on is with starting fluid into the inlet. without starting fluid takes no shit. 

Anybody know where to start to find fault, I dont think the halls sensor is the problem .... it may be a relay or a loose connection or a dead fuel pump, I do not know how I test the fuel supply and where it is best to start to find fault.

Lars Peter Mathisen wrote:Hello again. 

I have now tested halls sensor up to 160 degrees. It worked as it should without grinding to a halt. Super I thought    as I drove.... but no on the way home from a trip to the port I wanted to look at a BMW RT 1100 at the motorcycle dealer, I parked my BMW K100RT, I looked at the lovely Rt 1100 he had for sale. Here, after a quarter of an hour would I start my k 100, but never got life in it.    I've now got it home and the only way I can get it to turn on is with starting fluid into the inlet. without starting fluid takes no shit. 

Anybody know where to start to find fault, I dont think the halls sensor is the problem .... it may be a relay or a loose connection or a dead fuel pump, I do not know how I test the fuel supply and where it is best to start to find fault.

Have you tried the K100 2v EFI/Electronic ignition troubleshoot link? A step by step way to troubleshoot fuel and ignition problems...

http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm

Might be worth checking the fuel tank for holes in the base if you are getting a smell of petrol.
I've had that on two K's. One had pin holes on the bottom and the other, an '89 LT, blisters in the paint along the bottom seam.
Give them a poke and they turned into 3mm holes. Not funny if you were on the road.
Under the fuel pump and the opposite side of the tank seem to be favourite places. Water can gather there especially if you have the fuel cap on the wrong way round. Can't see them behind the fairing panels.
On a similar subject. Check that the rubber fuel pump holder isn't 'melting'. Bits can break off and clog the fuel pump and filter.
May be causing an intermittent blockage in your fuel supply and causing your problem.
Happened to me and brought the bike to a sudden halt. Fuel filter was completely blocked.

LPM, the first place I would look is the electrical connection to the fuel pump. If you have the connector at the front LHS of the fuel tank, the sockets can be gently squeezed to improve the contact.

And +1million on Bert's trouble-shooting guide!

Paul.

Paul

I had that issue on mine. But instead of taking the tank off to get at the female sockets I used a precision screwdriver to open up the male pins a little so that they made a tight fit. Worked perfectly. But I have a feeling that the 1988 tank doesn't have the connection at the front left but at the rear right.

We got started the beast tonight. We had messy with all the wires that were linked to the fuel pump, checked all fuses and fuel management and suddenly we got it started. Was agreed that it might have been a rusty connector to the fuel pump. Yes wonderful in such a lovely summer evening  , but the joy was short after 15 min drive went mc death once again.   I let it cool for 30-40 minutes but still would not start. sent my son home and pick up the car and trailer .. while I try with all the same lines as before  and suddenly it starts once again and I got the beast home again.
 But now we stand where we started without knowing where the fault may lie buried.   God I hate intermittent problems.  it is now a loose connection, the fuel control element or was it maybe just because it had finally cooled enough that it started????? 

Your problem is not heat related.  It sounds like you've confirmed the cause as faulty connector.  The remedy is to replace both the connector on the tank and on the harness with more reliable ones.  North Americans tend to use trailer connectors.  You won't find such connectors locally and will instead want something like this:
http://dk.rs-online.com/web/p/koretojsstik/8010780/
http://dk.rs-online.com/web/p/koretojsstik/8010783/

To verify that it's the tank connector that is the reason to the problem......

Measure if you got power at this connector when you push the starter button
when the problem is present.....brown=ground, green/white=12V+.

I had same problem on k100rs 1986...turned out to be dry joint on fuel pump wiring inside the tank on the fuel sender base which is held in by 4 screws at bottom of fuel tank.
Regards Tez