I am now measuring the time that I have been chasing this problem in years. One reason for it taking so long is that in the beginning it was extremely intermittent. It could go months without showing itself and then have it suddenly reappear. Lately it has been happening more often and grown more severe so I think I might have a chance of actually catching it. Although I would be more hopeful if the bike would just die and not restart. That day may be coming.

The bike is a 1985 k100.

Here are the basic symptoms:

When driving at a speed of anywhere between 45 and 75 (more often than not. Sometimes, although rarely, at slower speed) it would loose all power. The battery and oil light do not initially come on but the speedometer still showed electrical power. In the beginning, it would just momentarily cut out and then, after a heartbeat, surge back to life. Lately it has been stalling and it will take a little longer to restart.

It felt exactly as if the fuel was being momentarily cut off. Because of this I originally thought it was a fuel pump or filter problem but I have since ruled those out.

Because the problem only shows itself while driving, I can only troubleshoot it while driving. So, I connected a fuel pressure gauge to the line before the fuel rail and taped the gauge to the top of the tank. When it stalls there is no loss in fuel pressure. It remains correct.

So my next step was to hook up an led test light to one of the fuel injectors. It showed that when it stalls there is no power being sent to the injector. I then hooked up the test light to the injector pin #12 on the EFI computer. It also showed no power when the bike cuts out.

My thinking at this point was that either the efi computer is faulty, or something that informs the computer (like the airflow meter) might be faulty, or a wiring short between the two. If it was a wiring short then wouldn't the problem occur more randomly at any speed?

I opened up the air box and tested the continuity of the wires from the air flow sensor to the efi computer connector. I wiggled the wires around a lot but they each measured ok. I flipped the air sensor vane back and forth and it appeared ok to me. So I changed the air filter and put everything back together. It could be coincidence but after messing with the air box the problem did not appear for about two weeks. This is true to the intermittent nature of this problem so I really can't say that it is related to anything I did with the air box, as much as I would like to.

I have also cleaned the electrical connections at the electronic ignition controller under the tank and the ground near to it, the connection to the efi computer, and the connections to the air sensor, and the water temp sensor connection. I also ruled out the idle switch. The problem occurs i when plugged in or not.

So that is where I am at. I'm not sure what to do next. I'd like to test the air sensor or the efi computer but I am not sure how to test either while I am riding. Can anyone suggest a way to do so? I don't think the problem would appear on a bench test. Swapping parts would be great but I don't have a spare k100.

I still have a lot to learn about electronics and this bikes fuel control system. That is why I am turning to this forum. I'd appreciate any help I can get.

hmm sounds like that under seat connector is coming loose periodically

has happened to me too  a couple of time actually

what I did was to rebend the clip socket part that holds that connector in place ....so that the sharp edge of the clip is retained properly in the socket



 ....that was now a couple of years ago ....the issue has not returned at all

if you can pull the trailing cable from the connector pretty easy ....without going through the hole in the toolbox and levering the tab back ...have a look at the retainer clip ..

try deoxit on the connection pins - socket  as well


just my thoughts

and good luck

Are you aware that the injectors fire when a ground signal is sent and the 12v is applied all the time. possibly you are looking for the signal that wont register because the voltage is opposite to what you are trying to find. I would say you probably do know but many have been caught chasing a fault that does not exist.
I would be checking if the continuity of the AFM for smoothness by connecting the meter across it and moving the barn door slowly to see if there are any bad spots where the meter falters.  I realize you have tested the pump and pressure but have a close inspection of the 4 pin plug that connects the fuel tank to the main harness they are well known for problems that are like this and by opening out the small male pins you can eliminate any potential problems even if it doesn't help in this case.  The intermittent electrical problems are by far the most difficult to find but keep at it the Ks are certainly worth the effort.

Thanks all. I'll try bending the clip on the efi plug first since that is the easiest. I had previously cleaned it with deoxit and it seemed to be locking in tightly but I'll try again and report back.

If that doesn't work then testing the AFM while moving the vane will be next.

Thanks for the other suggestions Rick G. I should have said that my efi was not sending -12V at pin 12. Also, I have been through the fuel pump connector thoroughly and ruled it out for me but I know there will be others searching this post for clues to their problem and its a likely suspect.

Also, for anyone else having a similar problem, this link has been a great guide. It's specifically about starting issues but a lot of it applies;
http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm

I was looking again at that link that I posted and I remembered that I tested both pin 12 and pin 9 separately on the efi while driving. Pin 12 which sends the ground signal to the injectors failed to send the signal when the problem occurred .pin 9, which supplies a constant +12V to the injectors and the Air Flow Meter continued to show power while the bike cut out.

This make me think that the plug connection is ok. I will still try bending the clip but I not feeling hopeful. I will report back.

Just a guess is that the signal from the ignition ECU to the Jetronic unit contact #1 is lost.

Thanks Inge. This is where my ignorance on electrics and the bikes system will show. So bear with me.

On the link I posted it says that contact #1 supplies information on the engine rpm from the Ignition Ecu. It says the type signal is "Volts~" and the expected value is 10 - 20mv. Does the squiggle after volts mean variable? To test this contact could I plug in the positive lead on my LED test light to pin #1, grind the other lead and watch to see if the light goes out furring the stall?

That sounds correct to me.....and if the signal is present, it seems like the
problem is internal in the Jetronic unit....and if the signal is lost the problem
is internal in the ignition ECU.

the squiggle means that it is ac volts ......now bear with me
that means a pulse type signal  which I would guess is related to the engine revs
so would be better to measure it on the ac range ....that would make more sense to me  and show more voltage as well as there would be little dc component to measure ...but some none the less

I your meter does frequency you could measure that as well ...I guess at a more or less steady idle ?

I cant see a mention of any checks to the ignition or kill switch, if it stops after hitting a bump, or if you switch the ignition on and off or the kill switch on and off then it goes again, perhaps sorting them or confirming them as not a suspect may be beneficial before digging inside the bike.

I have cleaned the kill switch and the ignition. I also ruled those out for a few reasons. One is that the bike still has electrical power to certain things, like the fuel pump which I can still hear running when the bike cuts out. Also, bumpy roads don't seem to affect it. It is more likely to occur whith high rpm.

I bent the clip and cleaned the connector contacts on the jetronic but the problem still occurred.

I tried testing pin#1 before reading your post Charlie99. I'll test again tomorrow using the ac setting. But here is what today's test showed:

When I initially hooked up my led test light (with the positive lead plugged into contact #1) the bike would not start or would die as soon as the negative lead on the test light was grounded. So, I hooked up my multimeter instead and strapped it down to the gas tank and went for a ride. I had the setting on DC volts (I'll try AC tomorrow) and it read about 5.67 volts. It fluctuated by about .02 volts but the fluctuation did not seem related to rpm. When the engine.cut out then the meter would jump to 6.7 - 6.9 volts. When the bike would restart the volts went back to 5.67.

This additional point may be a red herring but when the engine would cut out I can still hear the fuel pump running. Today, as the bike would coast and slow down the fuel pump would eventually (after 2-3 seconds) shut off as the bike fully stalled . At that instant it would the bike would bump start and go back to normal running.

Not sure if this DC test tells anything. I'll report back with the AC readings tomorrow.

As the voltage rises just before it cuts out sounds like something in the
Jetronic unit shuts down.
Could be a idea to swap with a known good unit to test, if possible.

agree inge

I don't have access to a spare. I checked eBay and there is one for $168 that is close by. I may ask the seller if I could test it first. If it solves the problem I'd buy it, if not than I could pay him some rental fee and return it.

Is there any other test that I could do to further indicate that it is a bad jetronic? I

I assume they are not easily repairable. I have never seen any posts about opening one up.

I'll still plan to do the AC setting test, unless that's no longer necessary.

no longer necessary ....but could be usefull to future fault finding ....it would be interesting to see if the ac reading ceases as the fault develops ////and then becomes a dc only output .....indicates a few things to those in the electronic service industries

you have seen a change as the issue  arises and that would be enough to indicate the unit before the fuel injection computer ...ie  the electronic ignition unit ..

heres a question though

if only one of the hall effects devices fails ...what happens ?  does it make a difference to which one fails ?

I suspect that the pulses sent to the fi computer follow just one of the hall effects ..as the ignition follows a beat ratio  1-4 ....2-3

eager to be proved wrong ..or right



I don't remember ....did you clean the contacts of the hall effects connector to loom under the tank ?  I ask this as I have seen a fair bit of corrosion on my same connector ( now cleaned up )  but I could see that as a possible fail point ..

just thoughts worth pursuing I recon

From what I gather it is the 2-3 sensor that the ECU takes its signals by

I don't see how to quote on my phone so I'll do it manually:

Charlie99 said:
"you have seen a change as the issue arises and that would be enough to indicate the unit before the fuel injection computer ...ie the electronic ignition unit .."

But I thought that Inge, in the post that you agreed with, was suggesting that I swap out the Jetronic fuel injection computer. ???


When you say "did you clean the contacts of the hall effects connector to loom under the tank " do you mean the 15 prong connector to the EFI unit?

I did clean the contacts on the electronic ignition unit under the tank. I used deoxit and made sure the connector was tightly seated. For whatever reason, most of the contacts on my onld bike are remarkably clean to begin with and those were too but I sprayed them anyway.

no I meant the cable from the hall effects
it is a 5 pin plug  that then connects to the loom through a socket
sits about just to the right of the ignition computer under tank

just a thought at least

I'll check that connector.

How about for the parts swap? Are you suggesting the electronic ignition unit or the Jetronic? Seems like Inge was saying the jetronic.

Still planning on trying the AC setting test today. I just have to find some free time.

Thanks again for all the help.

Here is the result of today's test:

I had the multimeter still wired into pin #1 on the Jetronic and to a ground from yesterday's test. I started the bike and switched the meter to AC and got a reading of 11.6. I left the bike idling and was getting my helmet and getting ready to take a test drive when I remembered the suggestion to clean the five prong hall sensor socket. It had been idling fine for over one minute. I shut the engine off, slid the tank to the side and found the socket. It looked tight and clean but I cleaned it with Deoxit, reconnected it, and waited two minutes before switching on the key.

At first the bike started and ran for about 5 to 10 seconds and died and would not restart. The fuel pump ran, and the starter ran but it would not catch. I tried many times but it would not start. I disconnected the multimeter but still no start. I slid the tank aside, disconnected the hall sensor socket. There was still some residual deoxit so I dried it clean with a towel and reconnected. I also wiggled some other connections to make sure all was ok. After this, the bike started right up.

I know that the obvious thing would be to say that I have a short in the wiring somewhere but it might have been a temporary short due to the deoxit.

Here is another strange clue. Yesterday I had said that the bike would stall immediately when my led test light was connected to jetronic pin#1 and a ground. However, it did allow me to connect a multimeter between pin#1 and ground. So I took those DC readings while driving. But today, after going through the steps mentioned above, once the bike restarted, it now dies immediately when the multimeter is connected between pin #1 and ground or won't start at all if connected. ????? What could explain this?

you didnt perhaps bump he rhs electric controls connector ...just near there ?

they also corrode up ....this is the connector that has the kill switch combined ...and if intermittent could pose all sorts of issues

I guess you have cleaned that up before hand in any case ?

just wondering if 12 volts  output from the icu  to the under seat computer is natural state before signals appearing from the hall effects ?

im thinking that this sort of proves that the output from the icu ...is probably faulty ....if you are using a digital meter   ...unless you are doing the tests with an analogue - old style meter ....(these are too low an impedance to be used on almost all electronic systems where signalling is involved ...especially on the ac scale ) 


look around on the net ...im sure you can find another icu for cheaper than you have seen so far .

Thanks for sticking with me on this Charlie. I really appreciate it. Before I head out on my Ignition Module shopping trip I just wanted to push my luck and get your opinion again with a few more variables and all my remaining concerns thrown in.

First off, I had cleaned the rhs connector in the past and it had no affect. Also, yesterday when it would not start, the neutral light was on. When my kill switch is shut off then the neutral light does not light so am not thinking it was that connection. This morning I started the bike and wiggled all those wires and there was no change is steady idle.

Also, I am using a digital meter. I still think it is odd that it allowed me to start the bike while connected on one day and now it will not. Now it stalls out when grounded through the meter. Is this another sign of a bad ICU?

Here are my remaining concerns:

1. Should I look into the hall sensors before swapping out the Ignition Module? The sensors are one thing that I have not previously checked. I had ruled them out because from what i had read, that when they are bad then they need to cool down before the engine will restart. My issue does not do this at all. It restarts immediately, usually before fully stalling.


2. I had not mentioned this point because I did not want to confuse my original post. On my bike I removed the stock gauges and installed an Acewell combination speedometer and tachometer. I left this out of original description because the problem was occurring well before I made this swap. However, the tachometer on the Acewell gives very erratic readings. It is virtually useless. The speedometer and everything else work perfectly so I have so far ignored that issue and kept it in mind to fix once I got the stalling problem sorted. Because the stock tachometer had displayed correctly, I have not made a connection between the Acewell issue and my stalling problem. but now that we are looking at the computer and its reporting of RPMs, I wanted to mention it.


3. I am still wondering why Inge had written this in post #13 above;

As the voltage rises just before it cuts out sounds like something in the 
Jetronic unit shuts down.
Could be a idea to swap with a known good unit to test, if possible.

Maybe I'm misreading this but he seems to think it is a problem in the Jetronic. I do not understand this. I understand your reasoning, Charlie, that if pin #1 on the Jetronic is receiving information from the Ignition Module then a problem with that reading would be coming from the Ignition Module. Maybe I am misreading what Inge wrote?

kringb wrote:
Also, I am using a digital meter. I still think it is odd that it allowed me to start the bike while connected on one day and now it will not. Now it stalls out when grounded through the meter. Is this another sign of a bad ICU?

More of a sign of circuit loading by the multimeter, as Charlie alluded to earlier.  Most DMMs have very high input impedance (1MOhm or 10MOhm) which presents as small a load to the measured circuit as possible.  Your meter being digital should not present a load, but possibly the way you are connecting the meter might be leading to the symptom.  How are you hooking up the meter leads exactly? Are you sticking the meter probe into the connector shell? Maybe you want to take a 22GA solid copper wire bit, insert that into the connector and use alligator clips to hookup the probe.

I could understand how a test LED could affect the circuit.  It might pull as much as 20mA from the circuit.  A borderline driver circuit on the ICU might not be able to supply that current without consequence.

1. Should I look into the hall sensors before swapping out the Ignition Module? The sensors are one thing that I have not previously checked. I had ruled them out because from what i had read, that when they are bad then they need to cool down before the engine will restart. My issue does not do this at all. It restarts immediately, usually before fully stalling.

Sounds like your HES is functioning normally and is not the cause of your problems.  If the HES was bad, the bike would either not start or it would exhibit the symptoms you described (i.e. must cool down before the bike starts)

2. I had not mentioned this point because I did not want to confuse my original post. On my bike I removed the stock gauges and installed an Acewell combination speedometer and tachometer. I left this out of original description because the problem was occurring well before I made this swap. However, the tachometer on the Acewell gives very erratic readings. It is virtually useless. The speedometer and everything else work perfectly so I have so far ignored that issue and kept it in mind to fix once I got the stalling problem sorted. Because the stock tachometer had displayed correctly, I have not made a connection between the Acewell issue and my stalling problem. but now that we are looking at the computer and its reporting of RPMs, I wanted to mention it.

How are you getting the tach signal?  Is it through the Black/Blue wire (Pin 16 on the OEM cluster) coming from the coil #1 primary or some other means?  One way to eliminate the Acewell tach as a contributing factor is to remove the signal from the instrument and see if the problem changes.

Thanks robmack. Your explanation of why the LED test light would affect a borderline circuit in the ICU makes sense. The dmm is a cheap harbor freight freebie. Maybe it has a small load that is even closer to borderline of the ICU's bad circuit. Another thing I didn't mention is that when I was able to connect the dmm to pin 1 and drive it, my engine "cut out problem" was somewhat worse than usual,

I am connecting the multimeter by using 22GA sold wire pushed through the back of the connector and twisted tightly and taped around the meter's positive lead. I have another piece of wire wrapped around the negative lead and bolted to the ground at the tank minting bolt.

That is great news to hear about the HES. Thanks.

I do have the tachometer hooked up to the Black/Blue wire. I didn't really think that the Acewell was causing the problem. I was thinking that the erratic rpm readings it was giving might be a sign of something else that was causing the problem. But I guess not, it is a separate issue and something I can ignore for now.

I'm going to look for an ICU. I will be sure to repost how it works out.

good explanation rob ...

my take on it is that the under seat computer pin 1 is a input and unlikely to normally drag the ecu down on that signal .as the first thing it sees inside the efi computer is a 56k resistor ..so  the output of the ecu must be the issue ...or something along that path ?

it might pay to measure pin 1 of the efi computer with the ecu disconnected ...jus to see if there is some loss to earth or positive  internally  or even externally in the cable loom ...( you have proved the continuity from the output of the icu to the efi )...but is there a partial short between this wire and another or frame even ??

the acewell is probably looking for a low signal going high ...rather  than a high signal going low ...might help a little ( you could probably swap the terminal for the take off for the tacho to the other side of the coil ....and label the change ?)

Could you explain how I should test pin 1 on the efi with the ecu disconnected? Do I need to introduce a load into the wire somehow? I tried searching to understand how to test for loss to earth but just got more confused. I would like to prove that there is not a partial short in the wire before I buy an efi. Would another way be to connect a 22GA wire into the back of connector pin 8 on the ecu to the back of connector pin 1 on the efi and test drive it? if it still cuts out then the issue is not in the wiring? or would the extra wire throw off the system somehow?


Also thanks for the Acewell suggestion. I will save that and try it once I get this problem fixed. I may quote your suggestion in a new post as I try to work it out. I know that there are others who have hooked up the Acewell and had similar strange tachometer readings.

simply measure the pin 1 cabling  to earth on ohms scale ....200,000

same to a positive wire some where ...fuses maybe.. that don't have power in them at the time of measuring
power is off

sorry to be so dense on this but by pin 1 cabling do you mean female pin 8 at the disconnected ecu connector?

that will do

It took the readings. Ohms scale 200,000. One lead inserted into ecu female connector pin 8. The 15 pin connector connected to the efi.

With the other lead to ground: 8.6
With the other lead to one of the fuse connectors: 8.6

Those are pretty high resistance readings so the wiring should be ok, right?

I better think about that a bit ....8.6  hmm...  that would be 8,600 ohms ?

I know that you're not asking me that Charlie. I thought that I should move the decimal five places for 200k, to 860,000 ohms. That shows how much I know. I really appreciate that you and the others on this forum are willing to share your knowledge and brain time.

I can take readings though. Maybe something in this will help.

I ran the test again with a different meter and got the same results.

I disconnected the plug from the efi unit (ecu also disconnected) and measured pin 8 on the ecu to ground and to the fuse connector and got a reading of 1 (infinate?) on all scales.

I plugged in the ecu connector and measured from pin 1 on the efi to ground and to the fuse. To ground I got a reading of 1 on all scales. To the fuse I got a reading of 1920 at the scale setting of 2000k. 1 on all other scales.

By the way. I am removing the fuse and plugging my lead into the left connector on fuse 6 (the FI relay). I get a reading of 1 if I plug into the right connector of fuse 6.

I was planning on also wiring in a jumper between the ecu pin 8 and efi pin 1 and then to try to start and test drive the bike but it seems to me that these readings are saying that there is not a problem in the wiring connection. Is that right? But I can not tell if they are pointing in the direction of the efi or ecu.

infinite or close to is good on the efi computer pin 1  but the fuse must be in just not powered so that it also measures other circuits power through the harness

were looking for a partial short to another wire ....theres lots of controlled wires in there ...blinkers etc that also could be a sores of issue - short ...but it seems the very high resistance is what were seeing

so it leaves me to think that the issue is coming from the icu under tank


does that make sense

It does, thanks. I am going to get one and will repost after i get it in.

just a reminder to check -test the fi relay as well ....many have experienced funny issues with this thing

I had a vaguely similar problem for a few months last year. The engine would die but only when the throttle was off and the clutch disengaged. It was randomly intermittent. Could go a week without an engine fail and then it would die again. Checked all the electrical stuff bit by bit, cleaned all the connectors and earth connections, checked the readings on the pins etc etc but to no avail. Conclusion by all was that it was the FICU. Replaced that and it seemed to be fixed.... but a week or so later the problem was back. In the end it turned out to be the exhaust valve clearances (thanks to an astute member here). Re-shimmed those and I've not seen that problem since.

I think the lesson I learned was not to get a mindset about one thing. I'm not saying it's not the FICU. Sure, find another unit and swap it out but I think there are also other easy things to check which have not yet been mentioned.

The condition of the ignition circuit. Not talking about the ignition switch or ignition ECU but the power to the HT coils and leads. You can get loose wiring and a lot of corrosion around this area which will cause intermittent loss of power to the coils and SPs. Its easy to check this wiring and connections. There are also spade connectors in there which go back to earth. HT coils and leads can be a problem also but I'm thinking it's probably not on the HT side because it seems to be a complete shut down when it stalls.

The condition of your battery. A dud bat may still be capable of cranking the starter but under load it may be failing miserably and messing with the ECUs. Also, a bat in this condition will overload your alternator and possibly damage your starter relay. Its one of the most neglected service components of a bike. A lot of riders don't even look at it till the bike won't start or the engine stalls.

The state of the charge from your alternator. This will impact on the bat's ability to provide power while the engine is running.

An automotive battery shop will probably test the condition of your battery and alternator for free.

These things alone may not cause your engine to stall but combined with other issues and you could have a fail. Problems with battery/alternator/charge could impact hugely on a poorly maintained ignition circuit. The fact that your symptoms are getting worse could mean that a sevice component like battery or coil for example are slowly failing. Just something worth investigating as well.

Pity we're not closer. I'd gladly lend you my spare FICU.

Cheers

indeed nigel

We'll, I'm back to the drawing board and in need of more help. I got the replacement ecu and put it in on Sunday. I took it for a test ride and really pushed it and it ran great. However, riding to work today, all was going fine, I was feeling hopeful and even composing the Victory/Success post in my head when it did its cut out thing. There is one spot on my ride to work where it does it more often than other times. i don't know if it is related to the time of riding and the engine temp, the bumpiness of the road, the slight incline, or the because it is where the traffic usually clears up and I can speed up from 60ish to about 70ish. Anyway, that is where it cut out today. then after I got off the freeway and was driving on a side street it did it one time at low speed in second gear. (for a long time it cut out only at high speed but now, occasionally it will do so at slower speeds). So, unless the ecu that I got off ebay has the same issue as mine then i guess that I can now rule that out. I guess it is possible both are bad but that would be extremely unlikely to have the same symptoms right? Because the problem is erratic, it would take a longer driving test, months maybe, to say if one ecu is better or worse than the other.

Before I move on I wanted to give another piece of information that explains why I have been ruling some things out (maybe mistakenly). As I said, this problem has been going on for some time. it has been over 3 years now, though originally it could go 3-4 months without issue. At one point, not because of this issue, I replaced the engine on the bike and in doing so cleaned up, fixed, or replaced anything that was bad. This cut out was not the reason for the rebuild but I was hoping that it would be an added advantage and get taken care of in process. It obviously did not.

What to look at next? 

The battery: the battery is going and needs replacement. It is having trouble holding a charge when sitting for over a few days. When not used it can drop to 11.5 volts. i have been keeping it on a trickle charger at night which keeps it up over 13. After riding the bike the charge will be up over 13 also so I have assumed that the alternator and charging system are ok, just that the battery is old. It has been on my shortlist of needs but I have been putting that off, along with things like a needed oil change, while I focus on finally catching this cut out issue. Maybe that is bad thinking and I should get a new battery in there in order to test properly. But the battery was changed about two years ago and it did not solve the issue.

The condition of the ignition circuit. I'll take a look at this tonight and see what I can.I'll try testing the coils although I am not sure if that kind of bench test could identify an intermittent problem like mine. Also, would the coils failing also cause loss of signal to the fuel injectors?

Alternator: Because the battery is not draining while riding then i assumed that the alternator was ok. If this is a bad assumption, please let me know and i will try to find a place to test it.

Air Flow Meter: Because I had traced the engine cut off the the fuel injectors not being sent the ground signal from the Jetronic, I had originally suspected this might be the cause. Or at least I wanted to rule it out. I could not understand how to test it on the road so i was stumped. I can try Rick G's suggestion about testing the continuity as I move the vane. I'll just have to find the time to get it out of the air box.

Temperature switch. At one point I had the temp switch out and tested it and it was ok. However, I have wondered if there was a short in the connection to the Jetronic or something else related to this switch. Unfortunately I do not know how to road test this connection since the signal in the wire is a resistance signal and so i do not know how to tap into it without affecting it. I had considered connecting a jumper wire but have not yet done so.

Your symptoms are soooooooo much like Kaptain Holister's that I'd be seriously checking exhaust valve clearances.  His bike died at a certain spot in a regular trip, just the same as yours.  If, after checking, they seem on the minimum gap side (but still within spec), I'd consider opening up the gap a bit.

Thanks robmack. I'll add that to the list. I'm starting to think that there isn't anything on the bike that couldn't cause this problem. So far the only things I have positively ruled out are the seat and the air in the tires.

Even though the bike cut out this morning, I'm still not convinced that my original ICU is not also bad. With the original ICU I could not connect my led test light to pin 8 (ICU)/pin (1 efi), and when I hooked up my multimeter I got a lot of stalls at first and then could not even connect the meter without killing the engine.

After work today I tried this test with the new ICU installed. I connected the multimeter and it ran fine. The meter read a steady 11.7 volts AC. I drove the bike very hard and could not get it to stall. I will try again tomorrow and if still no stalling then I will try reinstalling the original ICU and compare. 

 I do have a question about this 11.7 V AC. On the chart on the troubleshooting page that I linked to above it says to expect 3-4 V AC from pin 8 on the ICU. Can anyone explain how I am reading 11.8?

dang ....almost a result ...but you have seen a change ...and that is a positive result ...of sorts

yes indeed rob ...clearances are a thought

cant explain the different ac measurements ...other than it could be the difference in meter ...some read true rms voltages and others measure peak ac readings ...so could be a little different ...perhaps?

kringb wrote:On the chart on the troubleshooting page that I linked to above it says to expect 3-4 V AC from pin 8 on the ICU. Can anyone explain how I am reading 11.8?

You have to know how your meter responds to varying waveforms (like Charlie pointed out), and whether the signal is pure sinusoidal or complex. The only definitive measure is to use an oscilloscope.

This one is so obvious you have probably checked it...but I dont recall seeing it mentioned above so what the hey....

The electrical connection to the fuel tank. I have had this come loose and create the exact symptoms you describe...

Mine is an 84 though which has a crappier connector, but still.....

good luck.

tried to post here 2 times ...lost it all on web page refresh
let me settle and try again ...in a while ......

kringb wrote:.... Something is causing the jetronic to shut off the fuel injectors. If the spark plugs stop firing for any reason while the engine is running, would the fuel injectors be turned off by the jetronic even while the throttle is twisted

Of course! If the engine stalled, power to the injectors would be cut. If the FICU recieved info from sensors that the engine was not running or something was critical then it would shutdown the injectors so that fuel is not pumped into a dead engine.

Exhaust valve clearances would not cause the injectors to shut down. When they are too tight, while the engine is cold it may start and run for a while. How well will be determined by how tight they are initially. As the engine gets hotter the exhaust valve clearances get tighter because the valve stem expands with the high heat from the exhaust gasses. When they are boarderline to start with, they very quickly go way out of spec which affects the valve timing and all sorts of things happen from popping and backfiring to engine stalls.
Chris Harris can show you how to check your valve clearances.

There is one BIG clue to your problem. Its progressively getting worse. Something is breaking down, running out or changing and going out of spec. Valve clearances progressively get worse. Also batteries run down.

kringb wrote:The battery: the battery is going and needs replacement. It is having trouble holding a charge when sitting for over a few days. When not used it can drop to 11.5 volts. i have been keeping it on a trickle charger at night which keeps it up over 13. After riding the bike the charge will be up over 13 also so I have assumed that the alternator and charging system are ok, just that the battery is old. It has been on my shortlist of needs but I have been putting that off, along with things like a needed oil change, while I focus on finally catching this cut out issue. Maybe that is bad thinking and I should get a new battery in there in order to test properly. But the battery was changed about two years ago and it did not solve the issue.

"The battery is going"... Smeg! It's gone!
At 12.45 V, a battery has 75% charge. Below this for anything but a short period and permanent damage will be done. At 12.0 V it's dead. If your bat is dropping to 11.5 V ... It's Toast!

Your battery's DEAD Dave... and its overloading your alternator which might damage other components in the charging/starter system as well as affect the quality of the HT voltage to the SPs and can even mess with the ECUs invalidating any tests you're doing. It could even be the cause of your problems. Either way, it's pretty difficult to troubleshoot an electrical problem with your current battery situation.

If its lasted only 2 years, that could be down to...
Poorly maintained battery. Trickle charging and allowing the battery to run down below safe levels, both for extended periods will damage a battery.
Damaged alternator. The only way to test an alternator is to measure the charge voltage across the battery at >2000rpm. Should be 13.8 V or more. Its ability to get the bat up to 13 V doesn't really say anything about the alternator's ability.
A short in the wiring that's draining the battery. You can measure the current draw (amps) from the battery with the ignition off. Not totally straight forward but easy enough if you want to give it a go... ask for a heads up if you're not sure.

Get a new 30ah battery and make sure it doesn't run down.

Thanks for the laugh Kaptain.

A new battery and a valve check will be next on my list. 

This morning I checked charge at +2000 rpm. In order to have a hand free for the throttle, I attached my negative meter lead to a grounded bolt (assuming that it does not have to be measured directly from the battery negative terminal) and got the measurement of 13.54V. So is my Alternator is bad as well?

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While I am working on these things, to give me something to think about, is there a way to determine if the spark plugs are firing while the engine is cutting out? I know the fuel injectors are not opening, if I could determine that the plugs are sparking then at least it would narrow my focus.

Can't say that definitely because the poor condition of the battery will draw the terminal voltage of the alternator down. You need a load test on the battery.

When I got home I tried connecting the multimeter again but it would not start while connected. I let it sit while I went to eat dinner. Afterwards, I tried starting it with the meter connected and then it would start.

And now I'm reconsidering my declaration earlier that nothing is wrong with your Hall Effect Sensors. They might be acting up. Your description above is now pointing in that direction and the problem does not move with the swapped ICU.