G'day gentlemen, Bob from Down under here (K100). Thanks for the website, it is a beauty. I have had a problem over the last few weeks that started out as a little blip now and then the old girl would cut out briefly and then continue on. Gradually got worse until it stopped altogether and i went over all the wiring in the shed. Thought i had it fixed after cleaning up the air meter connections (boy did that increase the power). Anyway last week a she cut out a few more times coming home on the freeway but then came good again and got me home. Was out the other day and went to come home and...nothing. I noticed the fuel pump wasn't coming on so a bit of a fiddle with the connector on the tank, off she went again. When I got home I replaced the connector, which had given me trouble in the past and was stuffed, also old broken plastic on wires. As luck has it I found a new one in the relay box under the seat that is there for the anti theft, very handy. Anyway came out yesterday to go for a ride...nothing. No fuel pump. Hmmm! Gerried up a couple of wires direct to connector, yep, fuel pump works. All earths are good, everything is connected, ignition lights on, starter working, relays clicking, changed the temperature switching unit (just in case, I noticed the pos+ wire goes there??) no fuel pump...Anyone got any ideas. One other thing, the headlight has stopped working...related? This is probably handled somewhere on this site but can't find it if it is. Can anyone help please?

Have you checked the load shed relay is working. That is driven via the starter motor and can give all sorts of strange problems if the brushes in the starter motor are a bit wonky (that's a technical term you understand) That is the first thin I would check as a quickie, failing that back to the troubleshooting pages - Bike won't start, and work through them systematically.
Regards,
K-BIKE

Do you hear the pump for one second after you briefly push the starter button? This is very important for the next troubleshooting step.

I was looking at the fuel pump circuit, and the load shed relay is not part of the circuit but the following components are:
Ignition switch
Emergency cut off switch
Fuel injection relay
Fuel injection module
Electronic ignition module
You can use the Interactive diagrams to follow the circuit.


What's happening when you press 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.

Have you check the connection of the fuel injection and ignition modules?
Do you have a problem with the Fuel injection relay? try to swap the FI relay with the horn relay. They are the same.

One of the symptoms of a failing Hall sensor is that it will work erratically or stop working when hot and regain fuel function after it cools down. After a while, it will even stop working when cold.
Your bike was cutting off when riding it. Did you have to wait few minutes before the engine started again?
Now that your fuel pump doesn't work, do you get ignition at the spark plugs when you push the starter button?
On the FI troubleshooting page I explain how to test the Hall sensors.


Good luck, and let us know what you find.
Bert

A not very technical comment. Has the fuel filter been changed lately?
I neglected to change mine and it stopped. Pump won't work if it is blocked either. I try to check the simple stuff 1st. Wishful thinking usually.

John,

I agree with you about checking simple stuff but Zeebob has the pump turning when he hot wire it. The other pesky problem is the connector under the tank, but again Zeebob replaced it.

Bert

Thanks for the quick reply fellas. Just to reply to you...No fuel pump at all before during or after hitting starter. Yes I have checked connections to FI and ignition module. Fuel filter changed not too long ago ( but thanks not something I had thought to look at). The power wire goes to the temp switching unit and I actually changed it cause when I was fiddling about and checking wires I broke the bloody thing Yes I have very good spark at plugs. Whilst travelling on freeway I never actually came to a full stop just rolled on in the emergency lane for a bit and then it came back on. it has only let me down proper when I have already been stopped and it then won't re-start. (At the moment it won't go at all...I will try swapping relays as suggested, if that gives no result then will go to hall sensors. Thank you, will get on to it when I get home from work (in my car ) and let you know how it went.

Have a great day...or in your case - good night, sleep well.

Hey Bert I have done the test for the Hall sensors and found the LED went on but didn't go out when the gap was obstructed.

The wires seem to short and get very hot. Is this normal?

Just to be sure I am doing it correctly please have a look at the photo :arrow: https://i.servimg.com/u/f60/14/90/89/11/hallse12.jpg

pos + to 3 neg - to 2 and bare wire going to 4. LED lights no go out when obstruction introduced.

If that all looks good to you then I may safely assume the Hall sensors are going in the bin?

regards Bob

NO, YOU ARE NOT TESTING THE HALL SENSOR CORRECTLY.
What you are doing as shown on your picture is just creating a short between the 2 rivets.



You have to do the test at the plug. What the schematic shows is the plug with the 5 connectors. Reinstall your sensors on the bike but do not plug them to the computer.
Any good sensor should light the LED until something metallic, like a feeler gauge, is introduced in to the sensors gap, the LED will then go out.



This is how to wire the LED

Thank you. Didn't seem right but there you go, easy to misread a diagram. I'll give it another go and see what happens. cheers

This is the problem with the forum. You never know what is the level of knowledge of people.
I always assume that if people start to play with the electrical, they have a good basic knowledge and I am not going into great details.
If anybody gave an explanation and it's not totally clear, you should ask for more details.
It's better to have a bike not running for another day and waiting for details than burning an expansive component.
I believe that the way you were testing didn't arm the sensors

Yay! She is going again...Can't exactly tell you why but I did discover that the relays are not interchangable. The FI relay is a 5 pin plug whilst the others are 4 pin. Having chased my tail all day I went back there and changed them back and voila' she goes... Re the hall sensor test I had no result unless I hit the starter button and turned over the motor. Seemed to make sense as light flashed on and off with hall sensor...Which begs the question how do you introduce feeler gauge if the thing is turning over..? Ai, ai ,ai...Anyway thanks for the assistance, I have ridden my local twisty circuit this afternoon (sunny & warm) and all is well in the world.

Hi,BERT
In your amazing interactive diagrams on the ground zone i see 2 main ground points,i know that one is under the tank but the other one i don´t imagine where it is. Can you explain me how can i find it?
thanks
Paulo k100

This can be confusing and your question is a good one.

These schematics are showing the principle and the wiring and are drawn for best readability. As an example, the position of the fuses on the schematic is not the same as it is in the reality. Another example is the brake switches and clutch switch. On the schematic they are all together and on the bike they are in 3 different places.


The 2 main grounding points are on the frame under the tank and on the side of the engine at the gear box level.

Hi again Bert
yes it´s a little confuse,when you said GEAR BOX LEVEL do you mean to tell GEAR BOX "LEVER"? If so on that zone i only remember the bolt to negative wire from battery to frame but i will see better next weekend
THANKS
Paulo k100

Yes, I am talking about the bolt from the negative wire from the battery.

Bert

ZeeBob wrote:Yay! She is going again...Can't exactly tell you why but I did discover that the relays are not interchangable. The FI relay is a 5 pin plug whilst the others are 4 pin. Having chased my tail all day I went back there and changed them back and voila' she goes... Re the hall sensor test I had no result unless I hit the starter button and turned over the motor. Seemed to make sense as light flashed on and off with hall sensor...Which begs the question how do you introduce feeler gauge if the thing is turning over..? Ai, ai ,ai...Anyway thanks for the assistance, I have ridden my local twisty circuit this afternoon (sunny & warm) and all is well in the world.

I will test a set of Hall sensors and take pictures of the whole procedure. Having the starter turning the engine produce the same result as closing the gap with a filler gauge. I know few riders using my procedure (One is my brother) and they were able to troubleshoot a bad sensor. The most important is that your bike is running again. It may have been a bad connection that has been fixed by taking the plug off and resetting it.Electrical can be funny sometimes.

That is another reason to treat every plug and socket and electrical junction on the bike with DeoxIT, these bikes have been out in the environment for a lot off years now and connections degrade with time, pollutants, oxygen and moisture.
Regards,
K-BIKE

This pertains to a 91 K100RS. Most of the information I found online were for earlier bikes and added to my confussion.
1. The fuel pump will get no voltage if the sidestand is out (or that switch is bad). The starter will crank. Just no power to the fuel pump. I lost half a day on that one.
2.) The yellow wire attached to the positive of the fuel pump is not the same yellow wire outside the tank at the connector. Power to the fuel pump is the Green/White wire in the connector. Don't ask me why. You will see lower voltages at the yellow terminal but that may be backsignal through the fuel gauge.
3.) I stuck my voltage meter pins into the female wiring harness to hold them. Bad idea. I stretched/deformed the females so when I reconnected the connector with the males I was making poor contact. Sometimes the fuel pump would work, sometimes the fuel gauge would work. I took a knife and slightly bent the females closed.
Hope this helps.

Thanks for the post guys.

My problem was the side stand switch has failed...
good idea to check this before going deeper..

For quick reference K1100 info below.