What the heck is going on?

barney t weasel

barney t weasel

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Number of posts : 10

An air leak seems to be present. Is this possible. Air leaking in may cause the pump to cavitate. good luck.

Bikesmith · **102** Re: What the heck is going on? Tue Aug 09, 2022 6:47 pm

Bikesmith

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Oh man, what a head-scratcher.

So, I thought I was getting close, but the problem is getting worse. Now the bike REALLY doesn't want to start. It will behave almost as badly as when it was at its worst for 20 or so start attempts. Starter kicks just fine. Fuel pump comes on and stays on until after the bike dies. But the bike just sputters to a stop. After repeated attempts to start it does get better. It will get to the point where it can just barely idle. Any gas kills it, The 'choke' switch kills it. After idling a few minutes it will start to have bursts of running better. Just for a second at first, but becoming more frequent and lasting longer until the bike is running okayish. Still definitely not great, but running. It will rev up for a moment, but then sputter and threaten to die unless I drop it back to an idle.

A squirt of starter fluid does help. For a moment after the squirt it will be able to rev up much better. Still not perfect, but noticeably better. After a few seconds it goes back to being wonky. That made me think gas delivery is the problem, so I've been taking another look at that.

The whole gas system is immaculate. I cleaned the tank super thoroughly. All hoses are new. Pump is new. Filter is new. Pre-filters on the injectors are new. I ultrasonically cleaned the injector rail. I wondered if I might be getting low voltage to the pump, so I tried connecting it directly to a 12-volt power source. No difference. I did a more careful pressure test. I don't know why I got 35psi the first time I did the test. Now I'm getting a very consistent exact 36psi, both with the external power source to the pump and hooked up normally. That's with the pump running but not the injectors. When the injectors start firing the pressure fluctuates a bit. Basically, the pressure gauge needle gets fluttery.

I do still wonder if the injectors themselves could be clogged, but with the random, sudden fluctuation between running badly and running okayish, that doesn't seem likely. I'm tempted to make a test rig for the injectors. I can use my old pump (which I'm pretty sure is fine), powered by external power, sitting in a jar of gas. I'll use that to supply the rail and a 12-volt source with a button switch to power the injectors to see how they're squirting. I might try that tomorrow, but honestly, I don't think that's it. Oh, and they're all clicking just fine while the bike is running.

I'm back to thinking that the coils are the problem. I tested them with my tester thingy again. I tried the tester at spec gap, .040, .060, and .080 inches. I used the same lead for each test. Just connected it to the 4 outputs in turn. At each gap I found that output 1 and 4 sparked okay (though I was not impressed by the spark), 2 was really weak, and 3 was basically not sparking at all. I know, I know, 2 shouldn't be able to be different from 3 but it just is. Really noticeably. I found this discussion about someone else having that same issue and there were some ideas about how that might be possible. Oh, and I tried switching the coils and got the same problem from the same coil even with primary wires swapped.

So it sure looks like at least that one coil is crapped out, right? It's weird that starter fluid helps, but I'm wondering if starter fluid can perhaps be ignited by a weaker spark than gas. Oh, and I do have the terrible black-capped early coils. I'm looking for replacements, but they seem kind of non-existent. BMW themselves say the part is discontinued. MaxBMW don't have them. I tried searching for the part number directly and found nothing. There are a pair on Ebay, but man they look terrible. And have no guarantee that they're functional. I'm very disinclined to go that route.

I did find this discussion that indicates the Dynatek DC1-1 could be a good alternative. 3-ohm primary, modern technology. Could be a good way to get my bike running again.

So, what do you guys think? I feel like I have JUST about exhausted all fuel possibilities. The internals of the injectors could still maybe be an issue, but I doubt it. I think I have a spark issue. In fact, I really think it's the coil (both?). The weak attempts at sparks it's making are just not getting the job done. Do the Dynateks seem like a good idea? I saw in that other thread about them that the mounts need to be grounded. Is there anything else I would need to do to make them work?

barney t weasel · **103** Re: What the heck is going on? Wed Aug 10, 2022 7:42 am

barney t weasel

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Number of posts : 10

Did you ever change the computer?

daveyson · **104** What's going on Wed Aug 10, 2022 8:25 am

daveyson

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So you think you've got problems do ya? This is the third time I've told myself to stop posting on this thread, and the third time I've snatched it.

You think we got problems, I found this from a past post by crazy frog:

What the heck is going on? - Page 3 Herse110

I think you're saying you have weak sparks from the coil for 2-3 even when swapping the input primary wires from the other coil. Plus it failed the resistance test. I'm thinking you want to replace the coils. But anyway I'd still check the resistance of the leads, it's an easy thing, especially cause of the strange cylinder four results (I think that's interesting, I'd be testing to see if it's due to cylinder one plug or lead, or something else)

Laitch · **105** Re: What the heck is going on? Wed Aug 10, 2022 11:05 am

Laitch

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Point-Seven-five wrote:I wouldn't take much of a stretch of imagination to see that the fuel flow is so severely limited that there would be just enough in the rail to start the bike, but not enough flow to sustain the running.

robmack wrote:If the rubber parts in your tank were deteriorated and turned to black goo, and the pump circulated that stuff into the fuel rail, then it is most likely that the filter in each one of the injectors was contaminated. Not enough to stop fuel flow but enough to reduce it. Having an injector overhaul may be in order.

Point-Seven-five wrote:Have you tried spraying some starting fluid in the air intake when the engine is struggling? If the problem is injectors sticking, the starter spray will make the engine run better.

92KK 84WW Olaf · **106** Re: What the heck is going on? Wed Aug 10, 2022 2:57 pm

92KK 84WW Olaf

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Silly question from me but is the fuel pump correctly seated in its position in the damper and mount? and the filter basked fully cleaned? Any issue like that affects fuel flow to all 4 cylinders equally.

Bikesmith · **107** Re: What the heck is going on? Wed Aug 10, 2022 5:05 pm

Bikesmith

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More update (sigh):

I tested the injectors. Rigged up this setup. 12-volt power supply feeding my spare pump through a toggle switch. Pump sitting in a jar of clean gas. Hose to pressure tester, through injector rail, through spare pressure regulator, back into the jar. Power supply connected through a momentary button switch to the injectors.

The system spun right up to 36 psi and held it. The button did bring lovely little sprays of gas (Video).

One of the injectors was a little dodgy. As soon as I had the pump running a little gas started leaking out of its nozzle. The spray was fine, but sometimes after I let the button go it continued to emit a dribbly spray for a few seconds. Then it would settle down to just a very slow leak. But not a happy injector. So I swapped it out for a spare (I still have a few old ones from when I was first reconditioning the bike). The spare worked perfectly. I went up and down the line of injectors testing over and over. I was getting consistently vigorous spray from each injector and they were closing instantly and not leaking. All four injectors happy. I thought for a moment (again) that I might have fixed the problem!

Installed everything back in the bike and it made no difference whatsoever Crying or Very sad

So here's where I stand on the fuel system: Clean tank, new pump, new filter, new hoses, fresh gas, ultrasonically cleaned injector rail, steady 36psi fuel supply, injectors all spraying beautifully and closing completely, fuel pump running exactly when it should (comes on with starter button, stays on until after the bike dies), injectors all clicking while the bike is running. It's getting hard to conceive of a way the fuel system could be malfunctioning.

Maybe, maybe... The injectors are clicking (all 4, every time), but is it possible they're not clicking at the correct rate? Or that each click is the wrong duration? I've checked my hall sensor every which way and it passes every test as perfect. I've tried swapping out the ICU to no effect. So the bike knows its timing. I guess... the timing could still be being lost between the ICU and the FICU, but I've cleaned all those connections several times. I suppose the FICU could be wonky, but wonky in a way where the injectors are clicking and the bike kind of runs? I don't buy it. Inputs into the FICU? I've installed a new temp sensor and swapped out my MAF for a spare (both tested good), cleaning connections while I did. It's hard to see how those could be the issue, but I guess it doesn't hurt to recheck the signals the temp and MAF are sending to the FICU. I don't suppose anyone has a spare FICU they'd be willing to loan me to see if that makes a difference?

More and more it's seeming to me like the coils are a likely culprit.

Answers to specific questions:

Barney Weasel - Definitely no cavitation from the pump. It's supplying a steady 36psi. Did I change the computer? I have swapped the ICU (no difference at all). I'd have tried swapping the FICU, but it seems like there are no used ones anywhere. A new one is $1500. I'd do that if I was sure it was the problem, but not as a shot in the dark.

Daveyson - I did check resistance on the leads. I couldn't remember the exact numbers, so I just went and checked it out again:
1 - 4.38K
2 - 4.69K
3 - 4.34K
4 - 4.77K

Laitch - I've owned the bike for around six years and have put about 18,000 miles on it. The previous owner changed out the instrument cluster, so the odometer is not correct. But I think the bike has about 80,000 miles total.

Olaf - The new pump came with new damper, mount, and fuel filter (which was a silver lining, since those were all kind of iffy). So the mount is totally solid and the filter is clean.

Jon

daveyson · **108** What's going on Wed Aug 10, 2022 5:43 pm

daveyson

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You're right, the injectors might not be opening for the correct amount of time, from Bert's guide you can test the FICU.

Maybe I'm missing some things, apart from an iffy injector, but it seems to me that you have done many tests and everything has passed, except for the coils, they both failed.

Bikesmith · **109** Re: What the heck is going on? Wed Aug 10, 2022 6:15 pm

Bikesmith

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Daveyson,
Agreed. I'll test the FICU. I think I already did and it passed, but honestly I'm not sure. I've been working on this basically every day for more than a month. I'm losing track of what I have and have not done.

But! I think I just got more confirmation. I pulled the coils and took a closer look, and I found this! The casing of the 2/3 coil is cracked. I'm certainly no expert, but I've looked a lot into coils lately and one thing I've seen over and over is that a cracked case is BAD.

Looks like replacement coil time.

Laitch · **110** Re: What the heck is going on? Wed Aug 10, 2022 7:43 pm

Laitch

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Bikesmith wrote:1 - I messed something up while tuning up the bike:
* Check throttle body sync. This was the last service I did before the problem (After the 20 mile warm up), so maybe the most suspicious. But I've done it dozens of times, and I didn't even do an adjustment this time. It was already spot on.

Bikesmith wrote:Laitch - I've owned the bike for around six years and have put about 18,000 miles on it.

The reason I asked how many miles you've ridden the Brick is this:
If you have ridden the Brick for less than 20,000 miles, why have you been compelled to do a throttle body sync "dozens of times" as you indicated in Post #10, when even in the most obsessive of ownerships (most until now, anyway, maybe Smile

) it is likely to be done only once every 9000 miles after valve clearance inspection and adjustment in conformance with BMW's maintenance schedule? Will you describe what you did and why you did it ≥12 times more frequently than recommended during a period of operation that you indicate the Brick was running well?

What is actually being described in this thread is starting to allude me so I'm looking for clarity in hope that my decline in cognition is only temporary and confined to my reading here cheers

; however, I can accept the outcome regardless, just as I have accepted that women for whom I would otherwise have instant lust are now opening doors for me with a sympathetic smile and calling me Sir. What the heck is going on? - Page 3 177381

What the heck is going on? - Page 3 177381

Bikesmith · **111** Re: What the heck is going on? Wed Aug 10, 2022 8:23 pm

Bikesmith

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Laitch,
There's a very good reason I do throttle body sync that frequently: Years ago I took the maintenance schedule from the Clymer manual and programmed it into a maintenance reminder app that I use. I'm really strict about doing everything on schedule. At the time, my Clymer book said to do the throttle bodies every six months. Upon checking, I've just discovered that that recommendation has mysteriously vanished from my book. So I guess I don't have to do it any more Laughing

I did think it was excessive, since I basically always just verified that the vaccuum levels were even and didn't do any adjustment. But it's so quick and easy and I bundled it in with other service I was doing. It never even occurred to me to check and confirm I had to do it that often. I have no idea at all where the idea came from that I had to it that frequently.

Thanks for releasing me from a maintenance duty! Very Happy

-J

Laitch · **112** Re: What the heck is going on? Wed Aug 10, 2022 8:44 pm

Laitch

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Bikesmith wrote:Thanks for releasing me from a maintenance duty!

The pleasure is mine, J, besides, you still have in the future the other maintenance—whatever that might have been—in the bundles you were doing during those 20K miles or so plus navigation duties in the voyage of discovery upon which you now have embarked. Things are looking good! What the heck is going on? - Page 3 112350

What the heck is going on? - Page 3 112350

Bikesmith · **113** Re: What the heck is going on? Sat Aug 13, 2022 5:17 pm

Bikesmith

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Number of posts : 137

It was the coils!!! cheers

I already mentioned that 2/3 was cracked. Upon closer inspection I noticed that 1/4 had a small crack too. So I replaced both. The stock coils are absolutely non-obtainable. They're nowhere. So I got a pair of Dynatek DC1-1s.

I had to make a mounting bracket for them (photo1, photo2), but then they just popped right into place (photo). The color is a little weird, but whatever Laughing

.

The wiring couldn't have been simpler. I did a quick check to make sure I was getting a spark out of them (fattest, healthiest spark I've ever seen), then fired the bike up. It has never run this well. It started instantly. Not even half a second. It sounded like it caught on literally the first revolution. Instantly went to a butter-smooth perfect idle.

Oh man, I was so relieved. It's done.

So, if you're considering aftermarket coils, go for it. Seriously easy to swap out.

Thanks again for all your help, everyone!

-Jon

Dai · **114** Re: What the heck is going on? Sat Aug 13, 2022 7:18 pm

Dai

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What the heck is going on? - Page 3 723598

daveyson · **115** What's going on Sat Aug 13, 2022 7:37 pm

daveyson

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Well done, and a well done thread too.

Question for down the track, are dynatek the same as k100 coils? See in the drawings, I think k100 coils (17 and 18 in the drawing, k75 coils being 19,20, 21) are different from k75 coils, and different from normal in that the secondary winding is independent from the primary. So the circuit goes from one plug to the other (rather than back to the battery) as in post 63, and the coil is connected to the ICU.

Are they the same and does it matter?

What the heck is going on? - Page 3 Img_2086

Laitch · **116** Re: What the heck is going on? Sat Aug 13, 2022 10:06 pm

Laitch

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Bikesmith wrote:It's done.

How much riding have you done with them, Jon? I imagine many K1002V owners will be anxious to know the outcome of your field trials.

daveyson · **117** What's going on Sat Aug 13, 2022 10:48 pm

daveyson

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Have you measured the primary and secondary resistance, and how much did they cost?

caveman · **118** Re: What the heck is going on? Sun Aug 14, 2022 7:02 am

caveman

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I too was attracted to this thread like a moth to a flame but could not help (lost by inconsistent results and performance). Very happy for you that you have it all sorted out and thankful to have learned that if I run across similar symptoms to have a good look at coils! Thank you for posting all this.

Laitch · **119** Re: What the heck is going on? Sun Aug 14, 2022 8:44 am

Laitch

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daveyson wrote:Have you measured the primary and secondary resistance, and how much did they cost?

From the model number J has given us, he bought a pair of dual spark 3.0Ω primary resistance coils for somewhere in the neighborhoods of 150–199USD per pair. Secondary resistance isn't listed on the Dynatek site, where I could find it anyway.

Point-Seven-five · **120** Re: What the heck is going on? Sun Aug 14, 2022 11:55 am

Point-Seven-five

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It would be really cool if he could post a tutorial in a separate thread on installing them on his bike with some photos. As these bikes get older this would be a great help to other owners in the future who have problems with these early coils.

Bikesmith · **121** Re: What the heck is going on? Sun Aug 14, 2022 3:40 pm

Bikesmith

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Hey guys,
So, I have only about 35 miles on the new coils so far, but I've tried cold start, warm start, hot start. All were instant. It idles perfectly smoothly, revs as much as I ask of it with zero hesitation. During the test ride I tried hard acceleration, revved up to 7000+ rpm, held it at 5000+ rpm for over 10 miles, got the bike really good and hot. It behaved 100% flawlessly. Not a single stutter. It was like a brand new machine.

I'm leaving on a touring trip on the bike in two weeks, so I intend to log at least a couple hundred miles before then to make sure everything is solid. Then (if all continues to be well) the trip will likely be 2000-2500 miles, so I'll let you know how everything is working after those milestones.

Daveyson, Primary resistance is 3 ohm, secondary is 13.2K ohm, and I got them for $177 (US) for the pair.

Point-seven-five, That's a good idea. I'll do that.

barney t weasel · **122** Coils Sun Aug 14, 2022 8:45 pm

barney t weasel

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Number of posts : 10

Well done. I had cracked coils on my Z1300 and just Araldited them. No probs.

Bikesmith · **123** Re: What the heck is going on? Mon Aug 15, 2022 4:25 pm

Bikesmith

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Hey! Guess what, everyone!

The bike is back to messed up.

I just went to go put some test miles on it, figuring to ride maybe 30ish miles today. After how well it ran yesterday I really didn't have any doubt the bike was back to perfect. I just wanted to get back to a place of totally trusting its reliability... And it had exactly the same problem as it's had for the last month.

I think I've shared video of this before, but here's what it's doing (video)

I immediately suspected the new coils, so I used my tester to check each lead from the coils. Nice, juicy spark on each of them.

I then sat down on the floor of my garage and cried for a little while.

After that I tried the only thing I could think of. I couldn't remember if I'd checked all the values at the FICU plug, so I did that. Here's what I found:

Signal from ICU was good (In fact, in doing so I realized that one of my anomalous readings on the ICU was because of testing error. Output from ICU to FICU is supposed to be 10-20mv. I was reading it as 20v because I didn't realize that with my meter set to mv of course it would read 20. 20mv, not 20v . Duh).
I'm actually getting no signal at all from the idle switch, but that shouldn't matter. The test guide itself suggests disconnecting that switch as part of the diagnosis process. As I understand it the bike should run just fine without that switch.
Signal from starter switch. This one is low. Reading 8.5ish volts, instead of 12. Same thing I saw into pin 6 of the ICU. But the problem isn't while the starter is running. It's after I let it go.
Signals from air flow meter. These are all within the ranges they should be.
Power to computer. Yup, 12v
Water temp. 1.6k ohms there. Right in the range in should be.
Ground to injectors. Reading 4.2 ohm, marginally higher than spec, but doesn't seem problematic.
Ground. Yup, it's ground.

So all the readings at the plug seem fine. Of course, that doesn't actually test the computer. The computer could be taking correct inputs and giving incorrect outputs. I don't know any way to test the FICU specifically other than replace it. And a replacement is $1500... For a part that is likely working fine. (Or is it?)

Oh, one other tiny clue I noticed today while trying to start my bike over and over again, hoping the problem would magically resolve itself: Holding the starter button down helps. Not completely, the bike still dies. But I'm almost positive it makes a difference. The bike runs maybe 10-15 seconds with the starter button held and more like 2-5 seconds if I don't. You can even see it in the video I linked. Watch my thumb. The bike is almost running while I hold the button and dies very quickly after I let it go. While holding the starter button, after the starter starts the bike it doesn't come on again.

That's all I have for today. This is really crushing me. Maybe tomorrow I'll be able to look at it again.

EDIT: So, I've been thinking about what was different between yesterday when it ran and today when it didn't. Here's what I've got for external context:

Saturday: I installed the new coils between 11 and noon. (That was the only change since the previous, failed starting attempt) Fired the bike up around noon (ambient temp 82F, 27.8C). Started instantly, ran perfectly. Idled, revved perfectly. Didn't ride. Ran the bike for 5 minutes. Didn't fire it up again until...
Sunday: Went for a ride around 2pm (ambient 91F, 33C). Bike started instantly. Idled and revved perfectly. Let the bike warm up for 5 minutes, the rode about 2 miles. Pulled over, shut the bike off, turned it right back on again (warm start test) Perfect start. Rode about another 10 miles, stopped for gas. Bike started up perfectly. Road another 20+ miles, including quite vigorously. Bike behaved absolutely flawlessly. Just like new. Pulled into my garage, turned the bike off, started it up again. Started perfectly. Shut off again until...
Monday: Tried to go for a ride around 9am (ambient 75F, 24C). Bike was completely back in non-working mode. Exactly as it has been for the last month. It had not been touched since it ran perfectly the previous day.

So, it was slightly cooler. The bike had sat unused for a slightly shorter time. But basically, I can't see what the difference was between yesterday and today

Dai · **124** Re: What the heck is going on? Mon Aug 15, 2022 5:12 pm

Dai

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Regarding the FICU: try taking it apart and checking for anything (anything!) visually anomolous (burn marks, corrosion, that sort of thing). S/H FICUs are going for about $90 on ebay here. Even Motorworks don't want more than about $200.

All prices approximate because I'm too lazy to go to oanda.com and enter some figures Very Happy

daveyson · **125** What's going on Mon Aug 15, 2022 5:59 pm

daveyson

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Ar shit no! And you're running out of time too.

Something I should have said long ago, consider my posts last.

I'd check for continuity between a coil secondary output and any of the primary connections. I'd open the spark plug tester to 10mm or the widest you can get a spark on. Maybe with test tube thingies you could measure how much fuel you get at each injector with say 10 seconds of cranking. Someone somewhere must have done that, I guess, to compare against.

Another ridiculous case of wishful thinking, wouldn't it be good if a jumper wire for the rpm signal solved the problem.

Point-Seven-five · **126** Re: What the heck is going on? Mon Aug 15, 2022 7:06 pm

Point-Seven-five

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Dai wrote:Regarding the FICU: try taking it apart and checking for anything (anything!) visually anomolous (burn marks, corrosion, that sort of thing). S/H FICUs are going for about $90 on ebay here. Even Motorworks don't want more than about $200.

All prices approximate because I'm too lazy to go to oanda.com and enter some figures

Again, try shooting some starter fluid in the intake to confirm that you have a fuel problem. Once you have confirmed that, try Dai's suggestion of opening the FICU. Your problem sounds a lot like intermittent fuel delivery. I would look very carefully for a broken connection or a cold solder joint that could possibly cause an intermittent failure.

I just checked eBay and there are no K100 Jetronic units listed at this time. However, there are several bike breakers selling K100 engines. You might want to spend some time contacting them and asking if they still have the fuel injection control unit that came with the engine.

You might also contact MaxBMW. They recently purchased the inventory of used parts from another dealer and may have a Jetronic.

daveyson · **127** What's going on Mon Aug 15, 2022 7:47 pm

daveyson

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A quick check. The harness plug for the injectors, I spose you cleaned them. The red/yellow wires (and the others) Are they fully pushed home into the plug?

Edit: and clean and tight at the back of the plug?
Just listened to the video, I'm thinking even the cranking speed seems too slow.

Last edited by daveyson on Mon Aug 15, 2022 9:46 pm; edited 2 times in total

Laitch · **128** Re: What the heck is going on? Mon Aug 15, 2022 8:11 pm

Laitch

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Bikesmith wrote: I don't know any way to test the FICU specifically other than replace it.

Have you tried the FICU tests in the troubleshooting guide?

daveyson · **129** Re: What the heck is going on? Tue Aug 16, 2022 2:53 am

daveyson

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Bikesmith wrote:
I'm actually getting no signal at all from the idle switch, ...

Is that with the start button pressed?

I think you should, that's a test fail. Have you messed with it in the past?

Here's another vote for the FICU troubleshooting guide.

Porto · **130** Re: What the heck is going on? Tue Aug 16, 2022 9:30 am

Porto

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If you have a very faulty fuel pressure regulator and no return valve at the tank it will not fire. I know this because I tried it on mine today. I fitted an adjustable FPR from a car with a gauge on it. When i dropped the pressure to below the minimum reading, flow only, I got a no fire condition. As soon as I dialled the pressure up so it would just start to move the needle of zero it would fire but not continue to run. Sounds very much like what you have described as the fault. Just an idea.

What the heck is going on? - Page 3 90170610

Bikesmith · **131** Re: What the heck is going on? Tue Aug 16, 2022 11:47 am

Bikesmith

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Daveyson, I'll check for continuity between primary and secondary, but these are brand new coils and they're making really impressive sparks. And yes, I've cleaned the injector connections. Plus, all four injectors are clicking when the bike is trying to run. The idle switch is something I'll look at, but the FICU troubleshooting guide actually recommends disconnecting it if you're trying to diagnose an FICU problem. Lack of idle switch won't make the bike not run.

Porto, The pressure regulator is brand new and a pressure gauge on the fuel system shows it rock solid at 36psi.

Laitch, See my previous post. I listed all the results of the FICU test. I'm getting no signal from the idle switch, which is weird but won't keep the bike from running. I have the same low voltage on the signal from the starter as I did on the ICU test (about 8.5v instead of 12). I'm going try to track that down, but the problem is not while the starter is running. So while it's a problem, I don't believe it's the problem. Otherwise, all pins at the FICU plug are reading correct.

Point-seven-five, A squirt of starter fluid does make the bike run great for a moment.

Dai, I had previous looked for used FICUs and came up empty-handed. All I could find were the super-expensive new ones. Your post, though, made me take another look. I tried searching for the part number rather than searching by "Fuel injection computer for 1985..." and I found one. Exactly the $90 that you predicted. So I bought that. It's on its way. I know I've received some criticism in this thread for using the purchase of parts as a diagnostic tool. And that criticism is correct. I could have saved myself a lot of money with more careful testing of what I had. In this case, though, I'm totally willing to spend $90 to eliminate the FICU as a possible problem.

So a replacement FICU is on the way. While I'm waiting I'm going to trace the voltage from the starter button to the ICU and see if can track down why the voltage is dropping. And I'm going to take a look at the idle switch to see why I'm not getting a signal from that. I'll check in again after I've had a chance to try the new FICU.

Laitch · **132** Re: What the heck is going on? Tue Aug 16, 2022 12:11 pm

Laitch

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Bikesmith wrote:Laitch, See my previous post. I listed all the results of the FICU test.

What is the number of that post, J? I found a list of ICU results but the FICU results are eluding me.

What did you do about the injectors; clean their screens? Did you verify firm relay connections as described GTJos's suggestion?

Bikesmith · **133** Re: What the heck is going on? Tue Aug 16, 2022 12:20 pm

Bikesmith

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Number of posts : 137

Laitch, post 123 has the FICU results. I replaced the injector pre-filters and replaced one injector that was leaking. See post 107 for more about how I tested the fuel supply system.
I have not yet checked relay connections. Thank you for the reminder on that! Tomorrow I'm going to dive into the wiring harness again. recheck and reclean every connection. I'll make sure to take a good look at those relay connections.

Point-Seven-five · **134** Re: What the heck is going on? Tue Aug 16, 2022 2:13 pm

Point-Seven-five

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Number of posts : 4223

Let me see if I am understanding the situation:

-You have new coils and a nice fat spark.

-The engine has compression.

-The fuel pump runs.

-The fuel pressure is correct.

-You hear the injectors being cycled.

-The temperature sensor is sending the correct signal.

-Starter fluid makes the engine run.

If all these are true, the engine is not getting the proper amount of fuel to run.

When was the last time you checked to make sure the injectors were spraying fuel when they were cycling? Are they actually injecting fuel? Are you actually hearing the injectors, or maybe the valves opening and closing?

Have you tried cranking the engine with the tank unplugged since you got the new coils? Is the engine being flooded with too much fuel to fire?

The fact that the problem apparently comes and goes abruptly tells me that there is an intermittent electrical problem. Since you have confirmed that except for the idle switch signal inputs to the FICU are good, I am thinking now that the FICU itself is suspect. I hope the replacement corrects the problem.

Bikesmith · **135** Re: What the heck is going on? Tue Aug 16, 2022 5:52 pm

Bikesmith

Silver member

Number of posts : 137

Point-seven-five,
Let me see if I am understanding the situation:

-You have new coils and a nice fat spark.
Correct. Plus, I have confirmed (several times) function of the hall sensor. And I tried swapping out the ICU.

-The engine has compression.
Correct

-The fuel pump runs.
Correct.

-The fuel pressure is correct.
Correct

-You hear the injectors being cycled.
Correct

-The temperature sensor is sending the correct signal.
Correct

-Starter fluid makes the engine run.
Correct

If all these are true, the engine is not getting the proper amount of fuel to run.
Yup, that's where my head is right now.

When was the last time you checked to make sure the injectors were spraying fuel when they were cycling? Are they actually injecting fuel? Are you actually hearing the injectors, or maybe the valves opening and closing?
Take a look at post 107, which I posted on the 10th. I made a fully external gas supply setup with pump, pressure gauge, fuel rail, injectors and rail, and regulator all set up off the bike. I saw directly each injector making a lovely spray of gas (Here's the video). As for actually hearing the injectors... I've been listening to each with a stethoscope. I was 100% sure I was hearing them click, but now you have me wondering if it's possible that I'm hearing valves through the injector bodies. I'll try disconnecting one of the injectors and see if I fail to hear the clicking on that one.

Have you tried cranking the engine with the tank unplugged since you got the new coils? Is the engine being flooded with too much fuel to fire?
I haven't tried that. I will. But if that were the case, wouldn't starter fluid make things worse?

The fact that the problem apparently comes and goes abruptly tells me that there is an intermittent electrical problem. Since you have confirmed that except for the idle switch signal inputs to the FICU are good, I am thinking now that the FICU itself is suspect. I hope the replacement corrects the problem.
Yeah, the fact that the bike is now switching between running really beautifully and not at all... That smells like a computer problem to me. I have high hopes for the replacement FICU. But I've had high hopes about several things I've tried already. We'll see.

I also have been putting together a list of additional things to look into:

The low voltage on the starter signal to the ICU and FICU. I don't think that's causing my main problem, but it is a problem. I'm going to trace the power from the battery through to the ICU plug and see where I lose that 3.5 volts. Probably a dodgy connection.
I realized that one connection I haven't cleaned yet is the connection between the main harness and the FICU sub-harness, so I'm going to do that.
Actually, tomorrow I'm going to pull the tank and really dive into cleaning/recleaning all the electrical connections. And I want to make sure connections to the relevant relays are solid.
I'm not suspicious of the battery, since it's only a month old. It's putting out 12.6-12.7 volts, that only drops to about 11.9 when the starter is running. But my local auto-parts store will test it for free, so I might as well do that. If the battery is faulty in a weird way, that could certainly be giving me some trouble.
I'll take another look at that idle switch. Actually, I think I remembered what's up with that. Years ago, I was remarking on how the instant, strong engine braking when you let off the throttle was unsettling. Somebody suggested rotating the idle switch to a position where it doesn't register idle. I can't remember if I actually did that or just thought about it, but I might have. That might explain the lack of idle signal. I'll look into it.

So that's where I stand. I plan to clean up the electrical connections tomorrow. FICU is supposed to arrive Friday-Tuesday.

-Jon

Laitch · **136** Re: What the heck is going on? Wed Aug 17, 2022 12:57 am

Laitch

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Number of posts : 3262

You aren't using the FICU to operate those injectors. How do they look when they're on the rail and the engine is cranking? Do you have a video of that?

Bikesmith · **137** Re: What the heck is going on? Wed Aug 17, 2022 7:26 pm

Bikesmith

Silver member

Number of posts : 137

Today was electrical connection day. I recleaned every connection. Really thoroughly. Cleaned up the connection between the main harness and the FICU sub-harness, which I hadn't done yet. Rebuilt ignition switch, starter and emergency cutoff switch. Checked and cleaned all the relay connections. Got the signal from the starter switch to the ICU and FICU up from 8 volts to 11. I had the battery tested (it was good). I checked the coil resistances again (perfect resistance on primary and secondary on both, no continuity between primaries and secondaries). Charged the battery.

Put everything back together and the bike fired right up and ran perfectly. It's idling happily as I type this, in fact.

Maybe something I did today was the key. I doubt it. I think more likely is that the FICU is in a happy phase right now. I'm absolutely going to pop in the replacement when it gets here Friday.

But maybe, maybe something I cleaned today was just what it needed. We'll see. I don't have time to ride today, but if the bike cooperates I'll be heading out tomorrow morning. I'll let you know how that goes.

-Jon

daveyson · **138** What's going on Wed Aug 17, 2022 10:06 pm

daveyson

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Number of posts : 1339

Bonus, maybe you fixed it, but if the problem returns you'll soon have a spare FICU to carry with you.

Were you saying the signal to the FICU from the start button was about 12V, then dropped to 8.5 with the button released? It should have dropped to 0 or maybe the button wasn't turning off properly.

Bikesmith · **139** Re: What the heck is going on? Thu Aug 18, 2022 12:21 pm

Bikesmith

Silver member

Number of posts : 137

Yeah, the bike is back to dead this morning Laughing

I pulled it into its spot in the garage yesterday afternoon, running perfectly. Even started it a couple more times just for the joy of hearing it run. It literally has not been touched since then. Today, totally dead.

No ride today, I guess.

We'll just see what that replacement FICU does.

Daveyson, No, the signal is 0 when not pushing the button. It was 8 volts while pushing the button, and after cleaning connections is now 11 volts while pushing the button. It was mostly the connection from the right-hand switch gear to the harness causing the voltage drop. I was hoping to be able to get it all the way to 12 volts. I think the remaining 1 volt drop is coming from the clutch switch connection. I cleaned it with Deoxit as best I could, but the holes on the female side of the connection are so small I can't really clean in there
.
I'm pretty sure that voltage drop wasn't the issue, though. The fact that the bike runs better while holding the button shows that the FICU was getting the message that the starter button was pressed. I guess 8 volts was enough for it. 11 is better, though. Very Happy

Oh! Also, my read on the starter button making the bike run better is that when the FICU is receiving that signal it's enriching the mixture for starting. Which shows that A) The bike gets closer to running with additional gas. Further evidence that the problem is, at its core, fuel starvation. And B) The injectors are capable of delivering more gas when they get the appropriate signal.

Another thing: The idle switch. It was, in fact, simply set to a position where it always thought the throttle was on. Once I rotated it a touch it behaved exactly as it should.

So the FICU is now receiving all correct inputs (aside from the starter signal being 1v low). All the physical/mechanical components of the bike have shown they are perfectly capable of making the bike run well. The bike can randomly switch from perfect running to dead without even being touched.

Come on, FICU swap! Save me from this nightmare!

daveyson · **140** What's going on Thu Aug 18, 2022 12:40 pm

daveyson

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Number of posts : 1339

If you move the FICU multiplug, check for any movement of the pins against the circuit board.

Bikesmith · **141** Re: What the heck is going on? Thu Aug 18, 2022 12:49 pm

Bikesmith

Silver member

Number of posts : 137

Daveyson,
A) Good thought. If the problem is, in fact, within the case of the FICU then Plan A is the replacement unit. If that works, then I'll feel free to be a bit more experimental with my current unit. I'll try resoldering joints, etc. Hell, maybe I can even determine which parts on the board are responsible for injector firing duration and replace them individually. It would be nice to ultimately have a spare.

B) Why are you still up? Isn't it almost 2am there? Laughing

-Jon

daveyson · **142** What's going on Thu Aug 18, 2022 1:09 pm

daveyson

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Number of posts : 1339

You're right, I was watching an episode of Sopranos, then woke up to find it finished, looked at the clock, thought no wonder I'm tired.

We were celebrating, my son just did a small roll in a movie coming out next year called Hoodlumz, and there was almost an opportunity for my brick to be in it. One of the actors from Sons of Anarchy is in it.

Anyway I don't have a computer, I post with my phone. If a post is made on a thread that I've posted on, my phone will beep. I spose computers don't do that.

daveyson · **143** What's going on Fri Aug 19, 2022 10:37 pm

daveyson

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Number of posts : 1339

If you post good resolution photos of both sides of the circuit board, someone might be able to see a fault.

By the way I realised the replacement coils were new, was just wanting to check that the wiring is like k100 coils, with the primary and secondary independent, unlike k75 coils where there's continuity between the two. And the replacements are like k100 so that's good. I guess maybe that's standard when a coil serves two spark plugs.

What the heck is going on? - Page 3 Img_2087

Bikesmith · **144** Re: What the heck is going on? Sat Aug 20, 2022 3:47 pm

Bikesmith

Silver member

Number of posts : 137

Okay, take this with a grain of salt since this is, what, the third time I've claimed to have the bike fixed? But I think I got it, you guys.

The new FICU showed up yesterday. I tried starting the bike with the old FICU first. It was, as I expected, dead. I swapped out to the new FICU, touching nothing else in the process. Took less than three minutes. Hit the starter and the bike roared to life instantly and ran perfectly. I'd say diagnosis doesn't get any clearer than that. Very Happy

I took the bike out for a short ride yesterday. It ran great. This morning it again started instantly and ran perfectly. I just got back from a 75 mile (120km) ride. It ran 100% flawlessly. Really fun ride, too!

Also, here's an interesting thing: I mentioned that I dislike the bike's harsh engine braking. That's why I disabled the idle switch years ago, trying to ease that harshness. It maybe helped a little but not really. The bike has just always been that way. Cut the throttle and you feel like you're going to get tossed over the handlebar. Until now. The issue is totally gone. The bike decelerates really smoothly now. And I think it comes onto the throttle from idle more smoothly now too. I think my old FICU might have been malfunctioning for years Laughing

One more thing: It's kind of moot, but I think I might have identified specifically how the old FICU was messed up. I was thinking about how randomly it switched from functioning to dead. Parked running one afternoon, dead the next morning without being touched, for example. Well, I think it was temperature based. I think the FICU was mis-processing the input from the air temp sensor at colder temperatures. And I think the reason I never noticed is that the threshold for proper function was just regular summer day temperature, maybe 90F (32C). Cooler mornings it was dead. Hotter afternoons it was running. Sometimes it was running badly, but just well enough to idle. Then the bike would run better and better as it warmed up. Once the bike was hot and running well it continued to run well for long rides. So I might open up the old FICU again, take a closer look at the temp sensor pins. It would, of course, be fantastic if I could fix it and have a functional spare.

Thanks once again for all your invaluable help! I couldn't have done it without you guys!
-Jon

daveyson · **145** Whats going on Sun Aug 21, 2022 6:59 am

daveyson

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Number of posts : 1339

Sorry, couldn't help myself.

Bikesmith · **146** Re: What the heck is going on? Tue Sep 06, 2022 2:35 pm

Bikesmith

Silver member

Number of posts : 137

If anyone cares about the followup... I'm back from a 2097 mile (3375km) trip on the K100. It ran flawlessly. Temps up to 104F (40C), elevations up to 12095 feet (3687m). The bike ran like a swiss watch the whole time through rain and shine.

Out of the probably 50 times I started the bike during the trip, there were three times when I pushed the starter button and the starter didn't turn. Each time the next push of the button started the bike. So maybe my starter relay could use a little more attention. But once the bike was running it was absolutely perfect.

So I'm going to go ahead and declare my problem to be well and truly fixed Laughing

. Oh, and the bike seems perfectly happy with Dynatek DC1-1 coils!

Thanks again to everyone for all the help!

-Jon

Dai · **147** Re: What the heck is going on? Tue Sep 06, 2022 3:00 pm

Dai

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Point-Seven-five · **148** Re: What the heck is going on? Tue Sep 06, 2022 7:02 pm

Point-Seven-five

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Number of posts : 4223

That is great news! Thanks for the update.

ddunks · **149** Re: What the heck is going on? Wed Mar 27, 2024 3:35 pm

ddunks

active member

Number of posts : 33

Hi Bikesmith, a useful read! 2yrs down the road are your dynatek coils still behaving? My originals are shot so if your recommendation still stands I’ll purchase a pair… an update would be great. Cheers

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