Electrical Gremlin Question

[Zampano]

I'll preface with "this will be difficult to explain" so feel free to mock and/or ridicule.

I have a '92 K75S. I've kept her going for about a year and a half but there as many issues as there are bolts. I'm sure these bikes were fine machines when closer to their production date, but I honestly have not been all that impressed with the uneccessarily complex (or the more laudatory "over-engineered" ;]) systems. To me it only creates more points for potential failure and motorcycles should be made to, at worst, be kick started and get you home. This bike I have is maybe an anomaly, b/c literally everything works poorly, from the seat latch and buckles on the sidebags, to the blinkers, lights, etc.)

Sorry, that's the smallest rant I could type. I needed to vent.

Now... my present problem is this:

The bike would sometimes only buzz the fuel pump when hitting the starter button. I tapped the starter relay, or would rock bike back and forth in first and it would "fix itself." Along with this there was intermittent headlight and blinker gremlins. I honestly never determined if the problem was the load shed, starter relay or starter brushes. I just lived with it for a few months. When the lights went out on me at night a few times I decided it was time to begin the fix.

Last week I removed the starter and replaced the brushes. Starter went back in, and bike ran fine (no blinker or headlight gremlins) for ..one day. On post op day 2 I push the starter and just hear "buzz."

I then remove the starter relay b/c in the past tapping it seemed to fix whatever gremlin was the trouble. However, the tapping may have been unrelated b/c sometimes you can shut the bike down and restart and that also would rid the gremlin. In any event, I removed the starter relay, took it apart and sanded the contacts. They didn't look all that bad to begin with and were not stuck when I took it apart.

I put the starter relay back in and still i just get the fuel pump buzz. I can hear a distinct clicking which I believe is the starter relay "working." But starter does nothing.

Also... the battery is relatively new. 6 months old.

* I think this is a big piece of the puzzle * --> What I did notice was that when pushing the start button the headlight no longer goes out. That made me think "load shed." My load shed relay (module) is the same as the horn relay. Or i should say has the identical numbers on it. My horn works, so i thought maybe I could swap them and have a bike which starts and has no horn. I swapped them and the horn still works but the bike acts the same.

At this point I know I'm missing something, hopefully simple. I'm thinking that the load shed is not getting it's proper signal from the starter. I believe the load shed gets a + from the starter which makes it cut the lights.

My thought is the starter relay may still be faulty even though it clicks. Or else maybe something is wrong with the brush plate I replaced?

Is there a way to simplify this entire circuit? Could I push the start button and then "jump" the 2 terminals of the starter relay? Or, is there a way to directly jump the starter? I know this will incur the wrath of many, but engineering begins and ends with a lot of "what the hell was i thinking" moments. Tomorrow I am considering taking the starter apart again in case something "fried" on the new brush plate. I'd like to avoid that if possible. I'm hoping to diagnose it to the starter relay or starter by a quicker method.

Sorry this is so wordy. Thanks for your help. Also, if anyone is in the san diego area and knows of anyone who may want to do a little work or help me out on the side for a few beans, please let me know. The bike has a rattle from the timing chain area (which may be something i can live with?) It also has a loud throw-out bearing and I have reason to believe the clutch was installed in a very barnjob manner. So in the future I would like to straighten the timing chain issue if it is indeed a failure on the horizon and/or tear down the clutch and make sure it is proper, which would also allow me to check splines and maybe do rear seal. I know that's a lot of work but not too bad if you take your time and get a little advice/assistance. But before any of that, i need to settle the starter issue, else I fear i'll be pushing this machine off a cliff soon.

thanks again.

[Scott_]

Ok, you say that you get fuel pump buzz(run), so that should eliminate the ignition switch and starter switch.

The fact that you say that the head light stays on, when you press the start switch tells me that:
1. the starter + lead is not getting power from/thru the starter relay,
2. the load shed relay is getting a good ground thru the starter brushes.

You could TRY for purposes of testing to jumper the 2 power leads of the starter relay to test the starter, but just remember you are dealing with unfused power direct from the battery. Make sure you are not in gear.........

[Zampano]

thank you.

Looking at the schematic my thought was to do exactly that. I wanted to confirm I wasn't neglecting something and possibly make matters worse.

Just now I turned the key, jumped the starter relay, and the bike started right up. The headlight cut out for the second it took to start the bike, so it seems that the starter relay is the problem. Could I be overlooking anything else?

Here's are the questions which you probably can predict.

If I start the bike this way is it functioning exactly as it would normally?
Will the bad starter relay give me trouble as I'm riding?

Could it be that something else is hurting the starter relay? I just changed the starter brushes and the battery is less than a year old. I'd hate to replace the relay and then fry that one because I neglected to check something else. As far as I can see the relay is the culprit. However it did look fine inside when taken apart and I can hear it clicking (or i think it is the starter relay) when I push the start button.

What would be the danger of wiring a heavy duty push button between the starter relay terminals until I find a working relay? With that I could turn the key and push that button instead of the starter button.

I dread ebay and will be searching the FS section here. If anyone has a starter relay they wish to sell please shoot me a message.

thank again for your help.

[Kyle10]

This may be blindingly simple but have you considered installing a beefier ground wire? The OEM one is pencil-lead thin.
I replaced mine with a what I believe is a 4 gauge wire ('twas long ago) and where I used to have the occasional buzz/crackle-intermittent-start I have now no problems whatsoever.

[Zampano]

This may be blindingly simple but have you considered installing a beefier ground wire? The OEM one is pencil-lead thin.
I replaced mine with a what I believe is a 4 gauge wire ('twas long ago) and where I used to have the occasional buzz/crackle-intermittent-start I have now no problems whatsoever.

Thanks. Someone who had the bike before me did that. The ground seems solid and the wire is pretty fat (I'd say 8 or less.) I had heard the ground was thin and was curious about mine.

[Zampano]

Now that i'm looking at the bike I have what I think is a very stupid question.

My ground is to a bolt on left side, down and to the right of where the coils are.

Are there other grounds to check? No other wires ground to this point. It is just straight to the battery neg terminal.

** now that i'm poking around I feel like a dummy. I believe i've found the ground wire you're speaking of. It is thin and probably worth changing. ** thanks

[Scott_]

The only other thing I could suggest for testing the starter relay.
Find the + side of the relay coil, either measure with a volt meter when you press the starter button for 12vdc, or with your testing jumper, connect it to the battery side of the load contacts and give it 12v direct to see if it engages the starter. (remember to be on the center stand or in neutral.......)

If the jumper test works to test the relay, then you are left with wiring(connections) in-between the relay coil and starter button.

It's possible that you could have a dirty/pitted starter button that won't allow enough current to energize the starter relay, or dirty connections in-between.

[Zampano]

The only other thing I could suggest for testing the starter relay.
Find the + side of the relay coil, either measure with a volt meter when you press the starter button for 12vdc, or with your testing jumper, connect it to the battery side of the load contacts and give it 12v direct to see if it engages the starter. (remember to be on the center stand or in neutral.......)

If the jumper test works to test the relay, then you are left with wiring(connections) in-between the relay coil and starter button.

It's possible that you could have a dirty/pitted starter button that won't allow enough current to energize the starter relay, or dirty connections in-between.

thanks. i'll give that a try. Would it make sense that the starter button would still engage the fuel pump. It buzzes when pressed. I'll need to trace the input to the relay backwards towards the starter button and see where the connections are.

Looking at diagram 86, the horizontal flat fin connector is +, 85 (vertically oriented fin) is ground. Should be easy to test the relay directly. Thanks for that.

[Scott_]

I got too much ch*t on my mind some days.....causes me confusion.

The starter button sends 12v signal to the computer input, and also sends power to the starter relay coil.
The fuel pump relay coil gets it signal from the computer.

so theoretically it's possible that you have just enough signal to trigger the computer to engage the fuel pump, but the switch may not pass enough current to energize the starter relay coil.

The diagram I'm looking at shows no intermediate connections from where the handle bar switch assy connects under the fuel tank, to the starter relay coil.
Same goes for the wire to the computer, no intermediate connection between the handle bar connection and the computer plug.

[rbm]

Have you checked the connector at the tank to make sure the contacts to the pump and fuel sender are not corroded or making poor contact?  There could be voltage drop across the contacts if they are intermittent.  A recommendation is to use Deoxit cleaner on all contacts.

[Zampano]

thanks again for all the advice.

I got underneath the tank and stopped short of disconnecting the connector w\the big plastic sleeve over it. It is fairly tight and with the sleeve around it I felt like i'd end up cracking one of these brittle wires or the connector itself; opening a new can of worms. Stupid question but are those designed to simply disconnect with the sleeve around it, or is that sleeve supposed to slide out of the way? I'm assuming the former b/c my sleeve is not going anywhere.

Putting a finger on the starter relay I can feel a strong click when pushing the starter. My plan is to swap a new relay in there and hope that is the only issue.

Since I know I can start the bike by shorting the two terminals on the relay, there is also the "barnjob" option of buying a high amp momentary push button switch and bypassing the original design for the time being.

Whoever designed the kick-start deserves a nobel prize.

[tg4360]

Replace the starter relay.

It sounds like the contacts are probably pitted from a past low battery condition.

[Zampano]

Replace the starter relay.

It sounds like the contacts are probably pitted from a past low battery condition.

Thanks. I agree. Ordered one this morning. I am curious if the starter button could be an issue or if it's worth changing any wires to higher gauge. Right now I'd just like to ride it and not worry. Roll the dice and come what may. If it fires up I'm "done."

I also learned from a tech at texas industrial, who really seemed to know what he was talking about, that the 332 002 150 is a worthy replacement to the original 332 002 161. The tyco/bosch module sold as OEM is a little different with a few diodes added but he didn't see the advantage and thought the original 161 was fine. Also he felt the 150 was a "better" relay because of a double contact lead which isn't on the currently recommended module. Apparently the 150 design could technically be rated up to 100 amps.

thanks again.

[Zampano]

for everyone's edification... I ordered the bosch 332 002 150 relay from the very nice folks at texas industrial. Came very quickly. So far so good. No electrical issues.

Now, on to the other googol problems