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1Back to top Go down   1984 k100 won't start. Empty 1984 k100 won't start. on Tue Aug 04, 2009 8:20 am

gabriel

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Hi everyone.

my bike won't start and im hoping to fix the problem through a process of elimination.
-there is spark and petrol is reaching the plugs because when I pulled the plugs out, they were wet.
-when i press the ignition, the starter spins but the engine won't turn over, and the engine will eventully backfire (a single loud backfire).
-pulled the ecu connector and checked for continuity with the sensors, all wires appear to be ok
-measured resistance value of the collant temperature sensor, a value of approx 2.6.
tested the resistance values at the airflow mass sensor , all values match the information noted in the troubleshooting section of this website. one minor concern, when i measured the resistance value of the sensor at pins 8 and 9 it was approx 198 ohms, and when i applied hot air to the sensor using a hairdryer, the resistance value changed to approx 184. my understanding is that the resistance decreases as the temperature increases. there was a small reduction in the resistance when i applied hot air to the AMS.
is this correct, and if not, is the unit faulty?
i will test the hall sensor asap. thanks for the info on this website. very helpful.

    

2Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Tue Aug 04, 2009 11:51 pm

phil_mars

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Hi Gabriel, I think the first thing is to get the engine cranking or do you mean it turns over but does not fire.

If the engine does not turn over but the starter turns I would suggest a mechanical issue e.g. sprag clutch or intermediate drive shaft so we need to try and get the basics sorted out first.

Regards,

Phil

    

3Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Wed Aug 05, 2009 9:58 am

gabriel

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HI phil

The engine turns over, but doesnt fire/start. there's a loud backfire and not much else!!!!!

    

4Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Wed Aug 05, 2009 8:11 pm

phil_mars

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Hi Gabriel,

Ok that makes more sense and it sounds like a timing problem. I think you mentioned in another post a problem with the hall sensor that Rene responded to?

Might be worth double checking the plug leads are connected in the right order if they have been removed otherwise I think it would be worth going through Bert's fault finding on the Hall sensors as it sounds like everything is happening just not when it is supposed to.

These things are pretty complicated for an old bus and it is easy to go off on a tangent.

Unfortunately these posts are quite common but I don't think I have seen the same answer too often.

Regards,

Phil

    

5Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Wed Aug 05, 2009 8:56 pm

Crazy Frog

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well, here is where I would start:

The bike seems to have sparks and fuel as it back fire.

Before replacing anything, remove the spark plugs, Have the starter cranking the engine to get rid off any excess of gas accumulated in the cylinders.

Get 4 new spark plugs, warm them up with a propane torch and install them.

Try to start the bike and see if you get the back fire again.
When a K100 is flooded, it is sometimes very difficult to restart it.
I even go 1 step further:
I light my propane torch and point it (for less than 1 second) at the spark plug holes. Sometimes you get a small explosion, but you are certain that your cylinders are dry after this treatment.
kEEP YOUR FACE AWAY FROM THE ENGINE! 🐒 Exclamation

    

6Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Thu Aug 06, 2009 4:02 am

gabriel

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must admit i haven't tested the hall sensor, but that's next on my list of things to do!! very informative article about testing hall sensors on this website. everything else is fine. checked the wiring from the ECU connector to the sensors, temperature, airflow, TPS, etc...no problems there... resistance values for the airflow mass sensor and temperatur sensor are ok...don't know about the ECU and ignition module, but i've heard they have a very low failure rate.
my suspicions are that it's the HAll sensor....i'll have another look at the bike this weekend!!!!! can't wait for daylight savings!
i'll keep you up to date with this situation...haven't checked the relays, but the grounding is excellent..fingers crossed!
i miss my bike and i desperately want to get it back on the road for summer!!! i want to do everything humanely possible before I take it to the experts $$$$$$$$$$$..

    

7Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Thu Aug 06, 2009 4:38 am

ReneZ

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Gabriel, are you measuring a resistance of 2.6 Ohm at 25 degrees C? Shocked That seems way too low. Is it KOhm? Otherwise the sensor is way off.

Aside from the very good information Bert has compiled or created on this side you might want to look here Exclamation


__________________________________________________
Greetings from Florida! Having a 'new' K  :cyclops:    Surprised-o: 

Rene


BMW K100 - 1985 (0030029) 1984 k100 won't start. Rain
BMW K1200GT - 2003 (ZK01223)
    

8Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Fri Aug 07, 2009 12:36 pm

Crazy Frog

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For a couple of days, I was trying to find the value of the air temperature sensor. Nothing is available on the Internet.
This morning, I decided to test it on my own. Here is what I found.
These data and procedure have been added to the EFI troubleshouting page as well as other information.

1984 k100 won't start. Thermistor3

1984 k100 won't start. Thermistor2

    

9Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Fri Aug 07, 2009 1:39 pm

ReneZ

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Wow, that difference in resistance over the temperatures is tiny. A bit of a dirty contact could easily become a problem. Do you think it is only used for starting and no more after? The limited change would almost make the signal useless otherwise. Good one you did it! It would be interesting to see what the resistance would be at lower temperatures. Appreciate however that you want to experience summer for a moment!



Last edited by ReneZ on Fri Aug 07, 2009 2:06 pm; edited 1 time in total


__________________________________________________
Greetings from Florida! Having a 'new' K  :cyclops:    Surprised-o: 

Rene


BMW K100 - 1985 (0030029) 1984 k100 won't start. Rain
BMW K1200GT - 2003 (ZK01223)
    

10Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Fri Aug 07, 2009 1:59 pm

Crazy Frog

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Yes the difference is next to none! I couldn't believe it myself.
You are right that a bad connection could have a big effect on the mixture.
This test has been done on a spare K75 airflow meter, but K100 and K75 are the same.
From what I have been reading about the L-Jetronic, it seems that the air temperature is always used (at any RPM) to balance the air/fuel mixture.

Now that we know what should be the reading, when we have problems, we could measure the temperature and temporarily install a fix resistor (matching the temperature) to fool the EFI.

Bert

    

11Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Fri Aug 07, 2009 2:07 pm

ReneZ

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Indeed. I'll have a look at a spare one I have here and see if the measurements are comparable. Good info!


__________________________________________________
Greetings from Florida! Having a 'new' K  :cyclops:    Surprised-o: 

Rene


BMW K100 - 1985 (0030029) 1984 k100 won't start. Rain
BMW K1200GT - 2003 (ZK01223)
    

12Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Fri Aug 07, 2009 2:10 pm

ReneZ

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Comparing these readings with the temperature/rersistance of the cooling water sensor, who's are over far larger scale changes a suitable resistance could indeed be beneficial.


__________________________________________________
Greetings from Florida! Having a 'new' K  :cyclops:    Surprised-o: 

Rene


BMW K100 - 1985 (0030029) 1984 k100 won't start. Rain
BMW K1200GT - 2003 (ZK01223)
    

13Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Fri Aug 07, 2009 2:15 pm

ReneZ

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I have entered the info slightly different, on a scale (not per measure point) and you see a clear change below 30 C. Just don't see how you can upload the graph??


__________________________________________________
Greetings from Florida! Having a 'new' K  :cyclops:    Surprised-o: 

Rene


BMW K100 - 1985 (0030029) 1984 k100 won't start. Rain
BMW K1200GT - 2003 (ZK01223)
    

14Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Fri Aug 07, 2009 4:33 pm

Crazy Frog

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@ReneZ wrote:I have entered the info slightly different, on a scale (not per measure point) and you see a clear change below 30 C. Just don't see how you can upload the graph??

Get a snap shot of your screen and post the picture.

    

15Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sat Aug 08, 2009 11:07 am

gabriel

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Hi everyone.

thanks for the info about the air temperature sensor and resistance values. Bert, your test results match the values i obtained. safe to assume that my airflow mass snsor is not faulty.
This weekend, i built the hall sensor testor described in this website and found that my hall sensor is fine. the LED lights when the sensor is unobstructed and switches off when a metal objects slides between the magnet. I found that no 2 on the hall sensor plug is the output for the top sensor and no 5 is the bottom sensor.
i also cleaned all the wiring and connectors including the relays using elecrtical contact cleaner. i noticed that the connectors for the hall sensor were very dirty and contaminated. ive put it all back together and everything works ok, lights, horn, indicators etc, but i didnt attempt to start the bike because i removed the engine cover and dont know what precautions to take to ensure i dont damage the engine whilst the oil pressure is building up. (the camshafts were perfect).
does a faulty fuel pressure regulator prevent a bike from starting? strange thing i noticed was a drip stain directly below the fuel line at the end of the fuel rail (which connects to the fuel pressure regulator). it gave the appearance of fuel dripping onto the enfine cover..
also, can a faulty relay prevent the bike from starting....im still hoping that the ignition control unti and EFU are fine, but you never know!

    

16Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sat Aug 08, 2009 11:34 am

Gezar

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try brand new plugs, NGK D7EA, about 11 bucks.

    

17Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sat Aug 08, 2009 2:23 pm

Crazy Frog

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Gabriel,

Re-visit the page on troubleshooting the EFI. I just upgraded and put something on the fuel injector. As stated, the EFI assumes that the pressure at the ramp is 36 psi and it will open the injectors according to this assumption (The EFI only controls how long the injectors open).
If the pressure regulator is badly leaking, you won't get enough fuel in the cylinders.
Have you checked your gas filter?
If yes, check your fuel pressure.
The advise of Gezar about replacing the spark plugs is excellent and I always start by replacing the spark plugs when I have a problem.

Bert

    

18Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sat Aug 08, 2009 6:06 pm

K-BIKE

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The small values and the small resistance change of the sensors absolutely underlines the comment in Bert's troubleshooting data about checking earths.

We are starting with 12 volts and sometimes less than that with a poor battery and then we are working with that on a device which is essentially out in the rain and pollution with non sealed plugs and sockets which regularly get damp and we are expecting current flows of a few milliamps to pass through without a problem on bikes which are now 20 plus years old.

As stage one of any old bike troubleshooting, going through every plug and socket and earth point is essential in order to have the bike as close to electrically new as it can be with the existing bits.

As a first step in ownership of any motorcycle go through every connection using Deoxit. Starting from the front and cleaning and treating every electrical connection will take at most a day and then every connection will be good for many years. The improvement in reliability will be worth it.
Regards,
K-BIKE

    

19Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Aug 09, 2009 5:24 am

ReneZ

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Gabriel, my question re the coolingwater temperature resistance? As you didn't respond I conclude you have ensured proper operation.
From all the above I understand that the Hall sensor is working OK, you have fuel and spark, but no starting at all.
Even reduced compression would give you a blurp or a noice and air leaks would still give you a start, but rough running.
Spark means ignition system is OK, however you haven't meantioned a check of the timing.
You have fuel, as the sparks are wet. Did you test the injectors out of the engine to see if they spray at intervalves or if they just leak?
Interesting one!!


__________________________________________________
Greetings from Florida! Having a 'new' K  :cyclops:    Surprised-o: 

Rene


BMW K100 - 1985 (0030029) 1984 k100 won't start. Rain
BMW K1200GT - 2003 (ZK01223)
    

20Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Tue Aug 18, 2009 7:03 am

gabriel

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Hi everyone

I think i'm making some progress with my situation. i've gone back to bsics and cleaned all the wiring including the plugs and connectors. gave the electonics a thorough clean. I noticed that the Hall Sensor plug was corroded. The rubber cover was damaged which allowed moisture and debris to travel along the wire and down the female plug. I cleaned it using electrical contact cleaner.
I also replaced the spark plugs. reconnected the fuuel tank. tried to start the bike, turned over a few times and actually started but stalled. I know from experience that it's going to take a few attempts to start the engine, considering the fuel tank was unplugged. The battery is now flat and i'm currently recharging it. i'll give it another try in a few hours.
i'm confident the engine will start. time will tell!!!!!

    

21Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Tue Aug 18, 2009 11:11 am

gabriel

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after several attempts to start the engine, it eventull fired but stalled after a few seconds. tried to apply throttle but the engine stalled. manipulated tha airflow mass sensor and the engine started, but i had to apply throttle to prevent the bike from stalling.
when the engine started there was a lot of smoke (oil) which eventually cleared.
after a few minutes trying to avoid stalling the engine, it stalled. i wasn't able to restart the engine.
i noticed a strange whirring/suction noise after the engine turned over a few times.
plese note, i did not replace the air filter assembly just in case I wasn't able to start the engine, it saved me from having to pull apart the airfilter components. it's a pain accessing the air flow mass sensor. did this affect the engine?
i was thinking is there a faulty compenent inside the engine which is preventing it from starting? faulty piston rings?
i inspected the spark plugs and i noticed that their tips were covered in oil and petrol. is this a problem?
the engine has not seized, it is turning over and for a few minutes, it was firing.
if i replaced the airfilter assembly, would this make it easier for the engine to start.
i removed the spark plugs to give the engine a chance to dry 9don't know if the cylinders are flooded.
any advice is appreciated.

    

22Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Tue Aug 18, 2009 11:55 am

Gezar

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I had a few problems initially on mine they were the following:
.
the small tube from the crankcase to the air box was missing this kept the airflow meter from working correctly. I tried a temporary fix and it pressurized the case(not good), I just replaced the hose, its the one located behind the far right throttle body.
.
I had to replace the injectors 3 of them were shooting a constant stream of fuel, no mist at all. I checked that by removing the 2 screws that hold the injector rail and pulled the assembly out of the case and tried to start it, you should see a mist spray.
.
the spark I was getting seemed strange, so strange and weak that I thought I may have a problem with my coils, I finally saw a good spark yesterday when retesting the compression. I pushed the small wires harder onto the coils, it may not have been a solid connection and the spark was much better.
.
initally my compression seemed weak yesterday, I just didnt have the gage in tight enough, 165-170psi on cylinder 1.(for me I would expect that, brand new rings, and I relaped the valve seats, and had to grind the shims to get it back into spec)
.
the thing that really did the trick was the newer injectors, I found some at a auto repair place and they were the wrong ones for the bike, very wrong, not impedance wrong, but flow wrong, 196cc/min versus 135cc/min and other flow diference, 18.65lbs very 12.85 I didnt write the what that was down but I think lbs/min or hour, you can check yours by keeping them in the rail, dont do this too long though, the fuel can ignite and come back out of the crank if it backfires, and use compressed air to clean around the injectors before you pull the rail out. and watch out for the small rings inside the holes where the bolts go to hold the rail in place. you can also see insdie with a flashlight at this point. and it is normal for 1-4 and 2-3 to squirt at the same time Smile.
.
the thing I have yet to check and could be a problem for me, is fuel pressure. it is supposed to be 36psi if your not getting stuff to burn inside then it wont fire.
.
when I was still in the testing phases with the engine freshly put together I did not have the mufler on, and I was able to hear small things initially, but I had several problems during that phase of the rebuild.
.
I cant remember if I read this or not, but and I mean but, if the bike sat with very little fuel in the tank or no fuel in the tank, there is a chance that the fuel pumps working end rusted, in my case my original pump was ruined, another pump I got in a tank I purchased ended up having its upper most seal dry rot, to say the least it sprayed fuel right out the rim on top. thus the close match pump I found at a local auto parts store.
if it can breathe IN and OUT, has something to burn in the right air/fuel ratio, and has a way to ignite it, it should run.
.
I realize this post has nothing to do with the electronics but that was an approach I could not afford, I had to hope the brains in the bike were fine. I cant afford those types of parts in one shot.
.
to better see if the pump has a seal issue, just open the cap, remove the 4 screws that hold the base in place, and remove it, you get a much larger opening to have a look see inside the tank. Be carefull removing those screws, use good screwdriver that fits properly and tap the driver with a hamer to shock them a bit, I was sloppy in my removal a few years ago and snapped the head off of one of those screws. This also gives you better access to go ahead and replace the fuel filter. just pull it off, and give the bike a turn, you should see huge flow and pressure out of the hose, use caution, it is after all flamable.
.
these are simple tests you can perform. Think in terms of a garden hose sprayer, if it looks like it is working on "full" mode then you have a problem fuel wont burn in a liquid state, if it looks like "mist" mode your fine.
.
I hope one of these things is the problem, I always fear the worst, but having dirt dobbers(wasps that build nests out of mud they pick up) make the crankcase a home is almost as bad as it gets.
good luck
.
Phillip

    

23Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Tue Aug 18, 2009 4:32 pm

Crazy Frog

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As you said, your post has nothing to do with electronic, but all your tips are excellent.
Quite often we are blaming the electronic for a lot of the troubles, but at the end the problem is only as simple as an air leak or a bad electrical connection.

With all the tips posted over the last year, when I will find the time I will start to write a document about all the 'little' things having to be checked when a problem arises.

Bert

    

24Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Wed Aug 19, 2009 8:26 am

gabriel

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I decided to check the spark plugs and I observed that spark plug 1 had no spark, the remaining three had a very weak spark, barely visible and it jumped from the centre electrode to the side of the main electrode. the sprark never jumped across the space to the tip. i previously checked the coils and i think the small wires are fine, will recheck.
how do i test the coils and spark plug leads?
any suggestions would be appreciated.

regards
gabriel

    

25Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Wed Aug 19, 2009 12:39 pm

Gezar

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I had exactly that, I do not know what I did to fix it,it was like all of a sudden the spark was correct and I do not know what I did. Like I said earlier, I pushed the connections back down really good, and got those new plugs....when I put them on originally they didnt have a much better spark...but from just fiddling all of a sudden wazam. I used a dremel and the sander drum to clean all my grounds during reassembly, and same with the battery connections even to frame. I dont know, spark outside looking rough, I checked the gap, and slightly filed on the post, massive spark after that. I think I have my gaps open a bit more then they shoudl be, about .031" or so. Seriously clean with a file those connections on the coils, inside the bits and out(I did not do this, im not even sure if I have them on in the right order, the paper I wrote the info down on was destroyed some how in the course of 4 years, I must have been lucky is all)next time mine starts to run sour im going to clean those contacts really good

oh another thing is dont test your plugs against the valve cover, rest them on the engine block or close to the battery ground, the valve cover is only connected to the engine by a spring.....

this is not the way you do this, but I check the wires with my hands, if I feel the spark, i have a shield failure.

from what I understand about the coils, is that they dont get any better then what you have more then likely. I wanted to get new ones so badly when I first saw my spark sucking. but at the price of a new honda scooter. I had to pass on getting new ones.

I saw the spark go from the pole to the side llike what you are saying, I also saw a spark like this | as well, then I finally saw a spark like this |||||, and the only thing I did was fiddle with those small connections on the coils. I just dont know.

Phillip

    

26Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Wed Aug 19, 2009 9:50 pm

phil_mars

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Hi Guys, one thing to be wary is the coils can have a tendency to develop cracks in the casing so checking the bike in a dark environment might tell you if there are any leaking sparks.

Gabriel I have a couple of secondhand coils which were working but have a couple of cracks so if you wish to PM me your details I can send them to you to at least try and see if it makes a difference.

Regards,

Phil M

    

27Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Aug 23, 2009 5:58 am

gabriel

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Hi everyone

I think i've discovered why my bike won't start. I noticed that I'm not getting any spark.
I removed the coils and performed a few tests in accordance with the Haynes manual. tested the primary coil and the resistance was approx 0.25ohms (terminals 15 and 1). tested the secondary coil and there was no resistance! i also tested the coils for continuity. the primary coil was closed whilst the secondary coil was open.

I checked terminal 15 and verified there was approx 11.88 volts reaching the ignition coils.
I am convinced the ignition coils are faulty an i have made a few enquiries about replacement parts.
Phil if you can post me the coils it would be appreciated. we can negotiate a price. i will reimburse you for any costs you incur. my mailing address is 255 high street windsor 3181 Vic.
any feedback would be appreciated.
Thanks
gabriel

    

28Back to top Go down   1984 k100 won't start. Empty Ignition Coils on Mon Aug 24, 2009 10:05 am

gabriel

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Hi everyone

I'm convinced that my ignition coils are faulty but i've spoken to a few mechanics who advised me that the chances of both coils failing is 1 in a million.
Is there someone out there who can perform the following tests and post the results. Ensuring all wires are removed from the coil, measure the resistance between +15 and +1 terminals. is there continuity between these two terminals. Resistance between terminal +15 and the HT output terminal. Is there meant to be continuity in the secondary coil?
Can a faulty load shedding relay cause a weak spark?
All feedback is appreciated. thanks.
gabriel

    

29Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Wed Aug 26, 2009 10:03 pm

gabriel

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i'm starting to have doubts aboutthe ignition coils.i spoke to a bmw mechanic who stated that the chances of both coils failing at the same time are "1 in a million" regardless it's always a possibility.
i'm going to test the spark plug leads. perhaps this is something i should have done asap. does anyone know the resistance values of these leads.
the fi relay is working, (fuel pump is pumping fuel!!!). assuming the leads are ok, working back along the circuit takes me to the ignition control unit. i don't know how to test that unit but i'm hoping it's ok....i know they are expensive to replace!

    

30Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Thu Aug 27, 2009 12:05 pm

gabriel

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h everyone
pulled the leads from the engine and obtained the following results; lead 1 approx 4600 ohms, lead 2 no result, lead 3 approx 5,6000 ohms and lead 4 approx 5100 ohms. is there any other way I can test the leads?
how do test for a spark?
regards
gabriel

    

31Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sat Jul 17, 2010 1:27 pm

bobthebob

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I'm curious about the eventual results of this situation... I'm having a very similar problem and would love to know what the problem turned out to be and how it was 1) discovered and 2) solved.

I realize this thread is 3 years old but I figured I'd try!
cheers,
bennett

    

32Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sat Jul 17, 2010 1:46 pm

wedge

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I suspect from the results of his HT lead checks and the fact nothing else was heard from him, he stuck new leads on and rode into the sunset never to be seen again.

Of course he may instead have tried the "hold the leads" trick and suffered a major cardiac arrest...

    

33Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sat Jul 17, 2010 2:00 pm

bobthebob

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lol!
well - if I figure out what's wrong with mine I'll post it for posterity.
if I don't - I'll be posting for help!
I have Crazy Frog's EXCELLENT troubleshooting guide so I can hopefully get to the bottom of things quickly - especially since my bike's sitting at a gas station about 15mi from home where it died a couple of days ago =((
cheers,
b

    

34Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sat Jul 17, 2010 2:02 pm

Crazy Frog

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@bobthebob wrote:I'm curious about the eventual results of this situation... I'm having a very similar problem and would love to know what the problem turned out to be and how it was 1) discovered and 2) solved.

I realize this thread is 3 years old but I figured I'd try!
cheers,
bennett

Do you have one cylinder missing or it's not firing at all?
First, replace the spark plug (I guess you already did it)
Switch the ht lead from a working cylinder to the coil not firing. If you get success and the trouble follow the bad lead, you have found your problem.
If switching leads doesn't change anything, check your ht coil. You can find how by clicking here

Well as I am replying, I see that you posted a follow up.


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35Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 1:13 am

bobthebob

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hi there Crazy Frog - glad you are around, if I could ask your advice?
here's the situation:
my bike is actually a K75 - an 87 K75S - but I figured most of the stuff wasn't so very different (except for the coils obviously).
anyway - I took a 20min ride, stopped for about 10min and then continued on, got about 100 yards down the road and the bike just stalled. starter cranked but engine wouldn't catch - a couple of times the engine would catch for maybe .5 - 1sec and then die. I rolled it back to a service station - put some gas in just to make sure, but that wasn't it since I had about 2.5 gallons in there.

so first thing I did was look at the fuses - aha! the number 6 fuse is blown! solved it!
but no. replacing the number 6 did NOT solve the problem.
next I checked that I had spark - and confirmed that I did. since it was bright daylight I wasn't able to really see if it was a 'strong' spark or not - but all three cylinders plugs were sparking 'straight' and appeared ok.
next I went home and remembered that I had downloaded your article months ago - so with that and a multimeter in hand I went back today.
I had a spare (confirmed working) FI relay at home and so first thing I just put that in to see - but no joy.
one thing I noticed is that I can NOT hear the fuel pump when the IG is ON, Trans in Neutral, Kill is OFF and the Starter is Pressed - nor can I hear it when the Kill is On and the Starter is Pressed.
I remember that I used to hear something that very much sounded like a pump before - but after looking around on the net I suppose that could've been the Load Shed relay...
in any case - now, NO NOISE.
so I started checking the FI relay circuit. I traced the red lead from the Battery to the FI relay (YES), then I went downstream starting with terminal 86 and checked for voltage with starter cranking. 11.7VDC all the way from 86 to the Fuel Sender Unit connector leading into the tank.
VDC might have been low from cranking the battery so much... Voltage measured at the battery was about 12.4VDC.

so - since I don't have a manometer I did a quick and dirty test just to see if the pump was working at all - I pulled the fuel line off the bar and put it into a clear bottle - then cranked the starter and - yes - fuel came out. not a very strong stream mind you, just 'some' - obviously impossible for me to say how much PSI, but assuming that a house faucet is about 45PSI I'd say it wasn't anywhere near 35PSI - but then that's just a guess and I only cranked the motor for about 3 sec so I don't know if that's enough time to achieve 35PSI.

anyway - I checked the injector voltage to see what I could find.
Injectors had power (again 11.7VDC)
Injector Resistance was correct (6Ohms)
I didn't pull them out because the bike isn't at my house (yet) and I didn't want to get dirt in the system.

oh - and I disconnected the Idle Switch and no joy there either.

I did some checks on the ECU but seem to not have made notes (DOH!) and now the only thing I can remember for sure is that resistance between terminal 1 of the ECU and the Neg Battery terminal was 8 kOhms - which seems high... your chart just says '.5 max' so I don't know whether that means .5 Ohms, kOhms, or mOhms.
I don't recall anything else being out of range...

anyway - the light was gone at that point so I left her and came home. =(

I DO have a spare tank with a good fuel pump - so that's my next move... but without a car it's a bit of a chore also...
if that doesn't work I don't know what else to do.
I suppose I should test the Hall Sensors as that seems to be a weak point and conditions were hot the day the bike died.
but later on that evening I went back and she still didn't fire up.
also - can you test the Hall Sensors without the bike being able to start?
of all the tests in your article that one was the only one I wasn't able to follow. I'm not sure how to apply the specs at the top of that page that has the diagram of the Hall Sensors.

so - help?

sorry for the Russian Novel here - I'm a bit stressed out and I have a tendency to go on when that happens.
thanks a lot regardless for the obvious amount of effort you put into that article. I appreciate it.

-bennett

    

36Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 1:27 am

phil_mars

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Hi Bennett and I think the one clue may be lack of fuel pressure and the lack of sound of the pump which should be quite noticeable but doubtless with the kill switch off.

Load shed relay sound will, hopefully, only be a "click" but the pump, on mine at least, is very noticeable whine.

The fuel pressure you noticed may just have been residual pressure in the line.

As you have a spare tank and pump that may be the easiest. Also you may have power to the pump but no earth so double check the connections.

The fact that fuse 6 is blown also indicates high current to the pump so it could be blocked, seized etc or a short circuit in the wiring.


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Phil
    

37Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 1:31 am

bobthebob

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hi phil - thanks, I had always assumed that loud <whine> noise was the fuel pump. I'll try it with the other tank and see what happens.
question re: checking earth connections to the pump - I assume it comes through the little 4 pin connector that goes to the sender unit? I'll check the wiring diagram and see, but is that the only ground? or do you mean the FI relay?
thanks alot.
bennett

    

38Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 1:37 am

bobthebob

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and yes on the Ohms Law thing re: the fuse.
I = V/R
when pump seizes or there is a short then R drops and A goes up and = blown fuse.
right?

thanks!
b

    

39Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 1:39 am

Crazy Frog

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I just got back from a street party and had too many drinks. Evil or Very Mad
I will wait to have a clear head to think about your problem.
I just read phil's answer and totally agree with him. The source of your problem is electrical and you have to find why fuse #6 blew out.
It already 1:30 am. and I am hitting the sack.
Sorry, good night!


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1984 k100 won't start. Frog151984 k100 won't start. Logo2101986 k75, 1985 K100rt, 1985 K100rt/EML GT2 sidecar, 1999 K1200lt/Hannigan Astro Sport sidecar.
    

40Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 1:41 am

bobthebob

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no worries! thank man... ;D

    

41Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 1:43 am

phil_mars

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Hi Bennet I am only going off the wiring diagram and my '84 100 has 4 wires but one would assume one was an earth.
I have a more broken down wiring diagram of the engine circuit which is more of a schematic but includes the K75 and basically shows one wire off Fuse 6 going to the pump and a return to earth and as the tank is rubber mounted I would suggest the obvious point is through the plug.

There are quite a few posts about the rubber fuel pump mount going soft and blocking the pump so I would not be surprised although the success rate after seems to be encouraging.

Might be worth checking the pump on your spare just in case......

And yes your theory re ohms law is correct and I had never bothered to break it down that far so that clarifies it. I had just gone seized motor=more current QED blown fuse. 1984 k100 won't start. Icon_biggrin


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Phil
    

42Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 1:45 am

bobthebob

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thanks phil - I'll let you know what happens next!
b

    

43Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 1:58 am

phil_mars

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Phil
    

44Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 2:37 am

K-BIKE

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Just a thought when checking if there is power for the injection that does not mean injection will take place because there is supposed to be a permanent positive on the injectors and the injection control puts an earth pulse on the other side of the injector and that causes the injector to open. An LED across one of the injectors (they all fire at the same time) will flash in time to the earth pulses from the controller.
Regards,
K-BIKE

    

45Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 4:14 am

bobthebob

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hmm - ok, that's a 12VDC LED yes? or else a resistor is required - correct?
thanks.
b

    

46Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 7:05 am

Rob Roy Mcgregor

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Not trying to be funny but are your leads all in the correct place both the head and coils ,also have you had the injectors and rail off to see if they are spraying 1984 k100 won't start. Icon_exclaim be very carefull to keep your hands away from the injectors while testing 1984 k100 won't start. Icon_exclaim also are the plugs wet or dry when you take them out .

    

47Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 8:40 am

ReneZ

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K-bike are you sure they all 'fire' at the same time? I thought they fired 2 by 2? Off course different for a K75.


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Greetings from Florida! Having a 'new' K  :cyclops:    Surprised-o: 

Rene


BMW K100 - 1985 (0030029) 1984 k100 won't start. Rain
BMW K1200GT - 2003 (ZK01223)
    

48Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 9:13 am

Crazy Frog

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@ReneZ wrote:K-bike are you sure they all 'fire' at the same time? I thought they fired 2 by 2? Off course different for a K75.
Yes K-bike is right. All the injectors fire at the same time.


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1984 k100 won't start. Frog151984 k100 won't start. Logo2101986 k75, 1985 K100rt, 1985 K100rt/EML GT2 sidecar, 1999 K1200lt/Hannigan Astro Sport sidecar.
    

49Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 9:18 am

phil_mars

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@ReneZ wrote:K-bike are you sure they all 'fire' at the same time? I thought they fired 2 by 2? Off course different for a K75.

Hi Renez, if you have a look at my post a few back on page 3 the link on Google Docs explains all, well some anyway. Smile


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Phil
    

50Back to top Go down   1984 k100 won't start. Empty Re: 1984 k100 won't start. on Sun Jul 18, 2010 2:34 pm

Rob Roy Mcgregor

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1984 k100 won't start. Icon_arrow 1984 k100 won't start. Icon_eek

    

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