Alright team,

It's time I ask for help from your expert brains.

I have a 1985 k100rs, and I can't get the thing to turn on. It had been running well, until suddenly my power started cutting out to the point where I could only start the bike by push starting it down a hill. Eventually it stopped turning on. This was a few months ago, so I'm forgetting exactly why I decided this, but I decided my fuel pump wasn't working. It seemed to not be pumping correctly, so I replaced it. Unfortunately, immediately after replacing it, I had to let the bike sit for almost 2 months while I was traveling.

Now, when I try to start the bike, the first time I press the starter I get a little of the muffled engine sound like its trying to turn over, but it lasts maybe 2 seconds. After that its just the battery cranking.

I know this isn't much information, but I'll answer any questions people have promptly. Someone has suggested it could be a computer or sensor, which I know nothing about. Does anyone have any ideas as to the problem, or ideas for tests I can run to determine the problem?

I know this is not a lot of useful information, but again I'll be watching the thread and responding immediately. I am broke and can't afford a shop, but I need the bike asap for work.. Any advice would be really appreciated!

Thanks in advance,
Ben

Are you saying that the engine turns over with the starter motor initially, and then lets go, allowing only the starter motor to spin? If this is the case, then there may be a problem with the sprague clutch. It could be gummed up from residue and needs a detergent based oil (such as Rotella diesel oil) to cleanse the assembly.

Are you hearing the fuel pump carry on 1.5 seconds after releasing the start button? If so, the fuel pump would be in order.

Follow Bert's troubleshooting guide to begin to narrow down your no-starting issue. http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm

If I am reading this right you can turn on the ignition and the lights come on? yes?
The bike cranks over but doesn't fire up.
You have not indicated if it runs the fuel pump for a sec or two after you stop cranking the starter motor.
Things that can go wrong are the ignition switch having the contacts corrode or get dirty. The wires feeding the pump can corrode and the starter can crank but not supply the earth after its finished cranking, All of these can stop or cause intermittent running.
Have you cleaned the wiring connectors for the pump and or the ignition. Perhaps by now it would be good to recharge the battery.

First make sure your battery is in top condition with full charge. Ks do not work well if the battery is low or old they do strange things.
Second don't be in a hurry to believe the computer either Ignition control (ICU) or engine control (ECU) is faulty they rarely give trouble and have proven to be exceptionally reliable.
The problem does sound like you have a bad battery.

+1 that. Well worth checking the battery. Must be greater than 12.45V. Take it to a battery shop to get it tested under load.
Worth checking the spark plugs as well. Their condition can tell us something about what's happening with fuel or ignition.

So my battery is certainly not great, but I don't think thats the big problem here.

This is a 15second video of what happens when I press the starter button:
https://drive.google.com/file/d/0BxjBsuob8jgFV2ZpTU4wVUZENnc/view?usp=sharing

The bike is on jumper cables in this video. The first time I hit the starter, you can hear engine sounds for a second, then the engine sounds go away and you can only hear the electronics.

As for fuel pump running, I don't hear it. To be honest... I feel like I never hear it... If people suspect thats the culprit I can just take it out and test it.

One of my early guesses was flooding, but even if i let it sit for a week and try again, the exact same thing will happen, so unless there is a lot of water in the engine or something...

Additional info:
-the lights work.
-pretty new spark plugs. Maybe I should pull one anyway to see whats going on in there.
-new fuel filter
-battery actually tested ok
-most ground connections have been recently cleaned
-I mentioned I let the bike sit for 6 weeks. This was during El Niño, and it was under a tarp, outside.
-When I returned from my trip (the 6 weeks), there was a LOT of moisture built up in the dashboard box. In the video, you can see that there still is (it comes and goes).
-on fuel side: besides the fluids I add to my fuel, lord only knows when the last time the fuel injectors were cleaned..


Thanks a million!

Sounds like the starter is working fine. Also sounds like the battery is strong enough. There's no sound of the pump running after you release the start button, so I'd concentrate on solving that problem first.

Yes I played that a couple of times and all I can hear is some bloke mowing his lawn. Do you have to hold the clutch in to start it? Were you in neutral? If that's the way it is then the state of the connectors on the bike may be a good place to start with the motor not going. It does seem to have enough oomph in the battery to start it, at least crank it over, so in all sense it should start. As Robmack says it will be tied to the fuel pump and the power it gets. Do you know how to use a multi meter.

Simple test for the fuel pump is to just tap the starter button and the fuel pump should run for 1.5 seconds after you release the button, the sound of the pump is very obvious. If this does not happen check the 4 pin connector to the fuel tank for corrosion and make sure it is contacting you can gently prise the pins wider or squeeze the female side tighter but take care. If that is OK and still no go check the pump pressure.
Remove the fuel cap (4 xhead screws and it lifts out). Using a long blade screwdriver or 7mm socket on a long shaft losen the clamp on the filter and separate the filter from the alloy fuel line and lift the filter out while still connected to the pump. Point the filter outlet back into the tank and tap the start button, you should get a really strong flow. If the flow is only weak fit a new filter and try again, if it is still the same place your thumb over the outlet and tap the start button, if the pressure is good you will find it difficult to stop the flow. Make sure the outlet is inside the tank or fuel will spray everywhere and then there is danger of a fire.
The filters often get overlooked and clog up, don't blow it out and reuse because it will just clog again very soon.

I couldn't hear any fuel pump but that could've been, as Keith mentioned, because of the lawn mower noise in the background.
The FI relay could be kaput. See electrical box diagram below. Might be as simple as corrosion on the connection. Try pulling it out and back in.

For starters (excuse the pun), do what Rick G says. There doesn't seem to be any noise from the fuel pump running. 

I guess the back ground noise is the engine of the vehicle that you are running the jump leads from (rather than the neighbours mower), but either way it does tend to block out any ability for us interested parties, several thousand miles away, to hear if anything other than the starter running. You shouldn't need your vehicle running to be able to jump your bike - I think you'll find that the vehicle battery has a few more Ampere hours (AH) than a bike battery, so no danger of flattening.

Possibly not the direct cause of your problem right now (but it could be, the bike will not start without it fitted), but something that will give you all sorts of issues in the future - your instrument cluster. You mentioned  a "lot" of moisture build up in it. Judging by the video, you were not kidding! It's not unusual to get a little fogging of the glass in cold weather, but yours is extreme and all that wetness is going to cause corrosion of the connector pins and internal components and affect the speedo and rev counter which equals an expensive cluster replacement.  I would strongly encourage you to remove it from the bike (quite straight forward to do, not forgetting the bolt/screw that holds the plug in place). Remove the back of the cluster (lots of long screws) and check that the seal is good (if missing or broken/worn you'll need to try and get a replacement) and check that the gortex vents at the back of the the unit aren't damaged. With the unit open, leave it somewhere warm and dry for several hours - but not too hot as you don't want to bake it. A sunny window sill perhaps. That should allow it to throughly and naturally dry out and get rid of all that excess moisture before you button it up again and put it back on the bike. Just a thought or two.

Good luck

Thanks guys.

I'll go try all of those this evening.

-I've done the fuel pump pressure test Rick mentioned before, which is what prompted me to get a new pump.
-The filter is brand new (as is the pump).
-The lawn mower is my 89 acura integra trying to power my bike. I'll do the video with a different car tonight (one with enough power that I dont need the vehicle running).

I'll try testing the fuel pump again, as well as the FI relay. I have no clue how to test or find the fi relay. Its been many years since I've used a multimeter, but i do have one.

Just to say, before the bike totally stopped there was a while - as I mentioned - when the bike could only start by being popped into gear. Maybe relevant, maybe not..

Thanks for all the input!

well, the fuel pump has no power. Just ran rick's test and not a drop is coming out of the filter.

to answer the obvious question, the two leads on the pump itself are attached correctly

So I guess I stupidly just replaced the fuel pump before verifying the power was okay.

found two helpful posts

First is BeachGuy's comment here:
http://www.i-bmw.com/showthread.php?t=37313

Second is in a different forum where someone said:

Engine turning, but no power to the fuel pump,,,Paul.
----------------
Then you could check if you got power at the relay socket, ....terminal 30 unswitced, terminal 86 switched.
And that you got ground at terminal 85 for a couple of seconds, when the starter button is pressed.

If you don't measure ground at 85, check at the yellow/brown wire at the ignition ECU under the tank, which
is the other end of the wire (keep the ECU connected).

Still nothing.......check that you got power at the black/yellow wire at the ignition ECU, when pressing the
starter button.

If you got power at this wire......the ignition ECU is the problem.

Also check that the ECU itself have good ground, brown wire.

Just looked up "how to use a multimeter" but could someone teach me how it works in this instance? Sorry haha.

For example, BeachGuy said I should test first the power wires coming off battery. Should I connect only the wire that goes to the fuel relay and put the red probe on the wire and the black on the frame, then do a voltage test?

And the fuse itself is okay, but would I test the connection with a voltage test or a resistance test..? (same question to test the relay)

Yes well first I'd make sure the black common or earth probe is connected to a good earth point on the engine frame, then the red probe set on 20volts or higher can be pushed into or onto the pump positive with the ignition on, remember to touch the starter (some will disc the starter heavy wire and isolate prior but be out of and away from the fuel then if no power go back one connector and test there, a four pin connector on the R/H side frame rail that runs down to the gearbox from the tank and check there. Have you a wiring diagram? One that shows the places for these connectors, It comes in the manual me thinks. You should be able to find it in here in the portal section. The F/I Unit is under the seat, and its the connector that can be loose or a little dirty that causes issues most remove and clean very carefully each little contact and stick it back together.

The FI unit under the seat is indeed a source of trouble, I found this on a K75 for a friend last year, had a similar issue on my own K in February. The connection on my own was intermittent, as is described, the clip that holds the plug connector captive had got a crack in it, allowing the electrical connection break down. Seems this happens a bit but the unit itself did not go faulty. I swapped it with the one in the LT and that solved it. I used a 3200 wet and dry paper used dry to clean the pins on the 'new' unit before popping it in. Its one of those little jobs I do every year. A suitable adhesive will repair the crack in the one I took out.

okay guys... so... don't make fun of me here...

So. Back in November, my bike died three days before a trip. As I mentioned, I worked pretty erratically and frantically to try to diagnose the problem before I left, and concluded it was the fuel pump failing. When I came home 2 months later, I replaced the pump and the bike still didnt turn on. I did a multimeter test on the fuel pump, and got a reading of .04v when I cranked the engine (read 0.0 standing). I did a quick check to make sure everything was connected, couldnt figure it out, and gave up due to lack of time.

Then I asked for help here. Someone mentioned checking the relay, so last night I proceeded to take off my gas tank to get to the relay boxes. I started taking off the gas tank carefully so I wouldnt damage the hoses and power going into the tank. I realized that there was none of the normal resistance when taking off the tank, so I looked under it. Sure enough, I never plugged the damn power cable back into the tank. Its a mystery why cranking the engine gave me any difference in reading on the fuel pump. Regardless, I plugged everything back in, and sure enough the bike fired right up.

I know...I know... Don't say it...

I forgot about the problem that predated my fuel pump though:

I rode the bike around the block for about 5 minutes, and came back. Waiting at a long stop light, my bike died. When I hit the starter, the battery was COMPLETELY drained, despite me having JUST ridden it. When I got home, a multimeter test gave me a reading of about 9v on the battery when the bike is turned off.
My question is: is this more likely to be caused by the battery needing to be replaced, or the alternator? I think I'd cry if it was the alternator...

bgambrogi wrote:okay guys... so... don't make fun of me here...

Sure enough, I never plugged the damn power cable back into the tank..... I plugged everything back in, and sure enough the bike fired right up.

I know...I know... Don't say it...

I rode the bike around the block for about 5 minutes, and came back. Waiting at a long stop light, my bike died. When I hit the starter, the battery was COMPLETELY drained, despite me having JUST ridden it. When I got home, a multimeter test gave me a reading of about 9v on the battery when the bike is turned off.
My question is: is this more likely to be caused by the battery needing to be replaced, or the alternator? I think I'd cry if it was the alternator...

Doh! you're not the first and certainly won't be the last to fail to connect the fuel pump plug.

But I do refer the honourable gentleman to posts 4 & 9 though - I still believe Rick is bang on the money.

For the battery to get that flat in 5 minutes suggests to me that your battery is kaput - even if the alternator was not working, there should be enough charge in a good condition battery for much longer than 5 minutes. If the battery is at the end of it's life, then the alternator will not be able to charge it.

"Well and truly r00ted" as we say here in Oz
Its more likely your battery is just incapable of taking a charge rather than the alternator failing to deliver. At 9V its past saving and has probably suffered plate damage. Having to jump start the bike is a pretty good indication the battery needed attention or replacing. I'd suggest paying slightly more and getting a sealed maintenance free battery like an AGM or gel type minimum 25Ah

Do not attempt to use the starter using the old battery!! There's a reasonable risk of frying the starter relay contacts and that relay ain't cheap.

To test the alternator, run the engine at >2000rpm. The voltage across the battery should measure 14.0V ±0.4V. (ie; 13.6V to 14.4V). If it's too low it'll likely be the voltage regulator/brushes. Its easy to remove, clean the contacts etc, check the length of the brushes, replace. Its at the back of the alternator.

Put the battery on charge for  about 8 hours then take it to an auto shop and ask them to load test it. They will do it free because they think a sale is there. It will be cactus (I will bet on it) then when you get a new sealed AGM type (Motobatt MTB30 is the best choice, I got 7 1/2 years from mine) check the charging. The ideal is 14.2 volts at 2000rpm. While your battery is out remove the regulator/brush assembly from the back of the alternator and check the length of the brushes. Haynes manual will show the proceedure with a few pictures. If you don't have a manual send me a PM and I will send a link to one.

Good job, now you know the connector is working, the rest will be easy

I am with the other guys on the bad battery.  If it's not an AGM sealed battery and you can't remember when it was new it is old enough to be totally whack.  As the others have said, if you keep using that battery, you are flirting with adding a new starter relay to the cost of getting things right.

Bite the bullet, you can get a new one for under a hundred bucks, and you'll be good to go for the next three or four years minimum.

I have had this battery in my K75RT for just over two years and 17,000 miles now and it has worked flawlessly.  It starts the bike even at 0 degrees F in the dead of winter.

https://www.batterystuff.com/powersports-batteries/sYT51913-22.html

Living in Sandyeggo like you do, you will be running the bike often enough that you won't need a tender, but if you do, this is a nice cheap one that has done the job keeping the batteries in three bricks happy over the long winter here.  Simple red/green LED tells you when the battery is charged.

http://www.ebay.com/itm/121917166470?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

just got a load test done. My battery was at 10% haha. 

...Hope I didn't mess up the starter relay   lol

So I've seen a lot of battery recommendations. I'm wondering if anyone can suggest a cheap battery (or tell my why I should not use cheap batteries). Like in the $60 range. I'm broke and I don't plan on having the bike for more than another year. Someone recommended Panasonic LC-X1228P, but after shipping its $75, and the Odyssey would be about $105. Is the extra 30$ worth it? Are there other cheap batteries? I don't know much about batteries or electrical stuff so I'm loving all your advice :p

I've seen them running around with ride on lawn mower batteries in them so how cheap are they up your way??

Hmm... And if I went to a battery store how do I know which lawn mower battery is the right one? What specs am I matching?

You need something at minimum 19Ah. Physical size and orientation of the terminals is important for correct fit/installation. I've seen some really cheap gel bats around but I couldn't tell you which ones. Have a look on ebay. Some guys here use golf cart bats and others use bats from solar systems. Do a search on the Portal page.
Cheers

Here are some good candidate batteries to check out:

OEM Battery (Yuasa 53030)
* Cold Cranking Amps (CCA): 325
* 20Hr Nominal Capacity (Ah): 20
* Reserve Capacity Minutes: N/A
* Metric Dimensions L x W x H (mm): 186 x 130 x 171
* Weight (kg): 7.7

Aftermarket Replacements
Deka ETX16L ($119)
* Cold Cranking Amps (CCA): 325
* 20Hr Nominal Capacity (Ah): 19
* Reserve Capacity Minutes: N/A
* Metric Dimensions L x W x H (mm): 175 x 100 x 155
* Weight (kg): 7.7

Yuasa GYZ20HL ($149)
* Cold Cranking Amps (CCA): 320
* 20Hr Nominal Capacity (Ah): 20
* Reserve Capacity Minutes: N/A
* Metric Dimensions L x W x H (mm): 175 x 87 x 155
* Weight (kg): 7

Odyssey PC680-P ($169)
* Cold Cranking Amps (CCA): 170
* 20Hr Nominal Capacity (Ah): 16
* Reserve Capacity Minutes: 24
* Metric Dimensions L x W x H (mm): 181.5 x 76.3 x 167.8
* Weight (kg): 7

Yuasa YXT20HL-BS ($119)
* Cold Cranking Amps (CCA): 310
* 20Hr Nominal Capacity (Ah): 18
* Reserve Capacity Minutes: ??
* Metric Dimensions L x W x H (mm): 175 x 87 x 155
* Weight (kg): 7

Rob Mack (and all),

thanks for the suggestions. If I go 100+ I'll get the odyssey. I was just wondering if there are suggestions in the "lawn mower" category.

But the Yuasa GYZ20HL is in that range. Although I think the Panasonic LC-X1228P has it beat:

Voltage: 12 V AH: 28 AH Type: AGM - SLA    CCA: 400   Polarity: RH +

Why is the Odyssey PC 680 so highly recommended? It seems that all its specs (the AH and the CCA) are considerably lower than the others..

The panasonic is 6.9" high. That will fit, right?

ugh. i give up. i don't understand this. the cheaper batteries have better specs!? people recommend the odyssey one over and over again, but it seems to have especially low specs to me... Rick G, i can't find the MTB30 you suggested.

I give.. I'll bump up my price. Someone just tell me what to buy hahah.


also, any idea why this says "Solar power"?

Oddessy batteries have construction differences which allows for deep cycle discharge, more than is possible with the Gel cells and cheaper AGMs you're looking at.


yes, it will fit. 6.9" is not too tall.

Rick G meant to type MBTX30U. That's what I use also but if I was to buy another battery for a K100 I would choose its little bro...

MotoBatt MBTX24U  US$125
AGM
24Ah
285cca

BMW recommend 25Ah and at battery shops where I've inquired, they've looked up the K100 battery requirements in their database which says 25Ah 320cca

Motobatt recommend the MBTX30U for the K100 only because the cca rating fits the spec at 360cca

EDIT: Have a look at some of these golf buggy bats on US ebay. Over 30Ah, unknown cca but they appear to be deep cycling batteries.
http://www.ebay.com/sch/i.html?_odkw=golf+cart+batteries+12+volt&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.TRS0&_nkw=golf+cart+batteries+12+volt&_sacat=0

There are a few there well under $100. Just need to check the terminal orientation and height as the terminals are protruding up.

These give a good choise
http://www.ebay.com/sch/i.html?_odkw=motobatt+battery&_sop=10&_osacat=10063&_from=R40&_trksid=p2045573.m570.l1313.TR1.TRC0.A0.H0.Xmotobatt+battery+MBTX30U.TRS0&_nkw=motobatt+battery+MBTX30U&_sacat=10063

The odessy is also a good battery.

Did you check the link in my post above?  $76 delivered in two days for a direct replacement AGM is the best deal I could find when I was shopping batteries.

Yes .75 that should do the job, Surely there is a battery place near him he can wander down to? Dollar wise it is a good price.

Thanks guys. You guys are super generous with your time in giving so much advice. this forum is great haha.

Point Seven Five, I saw the scorpion. It looks like a great deal, but I have been told to get a batt with 25ah or higher?

The motobatt and the odyssey are only 5$ apart. Seems like you guys would go with the motobatt? How does that Panasonic LC-X1228P stack up against them? It's 90$ to get it to my door, and seems to come highly recommended. Is it a good enough battery that its worth saving the extra money and getting the panasonic? (i promise after these questions I'm buying a battery  haha)

Guys,

I just wanted to say thanks again for your time in helping me. It all worked!

Of course now I have a new problem with the bie... but I'll talk about that in a different post hah.

Glad you got it sorted