Bought a 1988 K100LT last November. Totally love it even if it is not running all of a sudden. Mechanic said it was the starter relay but I've pulled it out and it seems to work fine so waiting for the freaking SNOW to stop and take another look at it. Thinking fuel pump relay...

In any case love the bike and looking forward to many miles of riding!!!

Hi there, what are the symptoms? We dont care about the snow in order to start helping.
And welcome
Best regards
JAP

Wow, that was fast.
I made a mistake. I had the bike on a 6V battery tender for December. (Not sure if this matters but ...).
The bike ran fine for about 2 weeks on many short trips.
1 morning I drove about 3 miles and lost all power and it was making a clicking noise right under my seat (crotch) and as it was failing when I gave it more gas it stalled sooner. It started a few more times only to stall again within seconds. After that would not start at all.
When the starter is pushed it sounds strong and the bike turns over but it never catches - no firing at all.
I have since cleaned the plug, charged the battery and pulled the starter relay out. The relay has one worn contact point that does not make contact but I don't see how this would make a difference but I know nothing about the relay. Under my finger is the contact point spoken of.
Photo attached.

btw-when I hook the copper terminals on the bottom to a battery everything seems to work on the relay. The copper become a magnet and the top half click down (although only 1 contact point).

I posted in the other thread you created with tips about the starter relay and starter motor. It seems that the starter motor and start circuit is operational.

Your problem might be related to poor electrical contacts. It is important to make sure all connectors are making good electrical contact. It would be a worthwhile exercise to disconnect every connection you can find (and get ahold of) under the tank. For each contact set:
1) Separate the contact set (male/female)
2) Spray the contacts with electrical contact cleaner
3) Mate and dosconnect the connector set several times to make sure that the contact cleaner works and removes oxidation.
4) Some people on this list recommend using De-oxit. This is a contact enhancer; it improves contact lifetime by putting an airfree barrier over the contact surface. Don't use a contact grease because it will do the opposite and maybe cause more problems for you.
5) check female connectors to make sure that they are closed enough to make good contact with the male counterpart. Squeeze them gently with needlenose pliers if they are opened.

Do this process for all relay connectors in the fuse box as well. K-bikes are notorious for exhibiting weird electrical problems related to poor contacts.

Another suggestion is to remove the starter motor, disassemble it and clean it thoroughly. The starter motor is used as a ground return for much of the electrical system on the bike. Motor brushes within the motor wear, giving off dust that causes resistance. This resistance inhibits electrical current flow. This starter motor cleaning will take less than 1/2 hour to do and can eliminate many gremlins. While the motor is apart, make sure that the brushes are not worn (highly unlikely given the service cycle of the starter circuit) and that the commutator is not worn as well (also highly unlikely). Reference

Hope that points you in the right direction.

It does. Most everything on the bike seems fairly simple mechanically although I've run into one embarrassing problem. I'm having trouble getting the fairing off without breaking anything and I can't find a "how to" anywhere.
-JR
1988 K100LT (my first)

Ps. and thank you for your advice - it will be taken!

jr wrote:It does. Most everything on the bike seems fairly simple mechanically although I've run into one embarrassing problem. I'm having trouble getting the fairing off without breaking anything and I can't find a "how to" anywhere.
-JR
1988 K100LT (my first)

Look at this writeup by Drake Smith. It might be helpful. Much better than breaking expensive parts.

That's is PERFECT. I'll let you know how it goes! I am THRILLED I found this forum!.

Hi jr. Welcome to the forum.
It may well be the relay but I had a similar problem a few weeks ago. Ran for a couple of miles then spluttered and wouldn't restart.
Turned out to be the fuel pump. Have you checked it?
If you open the fuel cap and press the starter you should hear the pump buzz for a couple of seconds after releasing the button.
Its not unheard of for it to fail after the bike hasn't been started for a while.
By the way, check out the downloads section for downloadable workshop manuals.

Hi jr,
The use of a 6 volt battery tender is not a good idea because it will only charge when the battery is down at about 6.7 volts which is dead- deceased 12 volt battery territory. The buzzing clicking under the seat sounds like the start relay was not getting enough voltage to stay pulled in and was cycling in and out. Fully charge the battery on a 12 volt car battery charger then use a 12 volt battery tender in future.

Both relay contacts should close simultaneously when the are pulled down by the magnetic force between the coil core and the armature. Check there are no iron filings sitting on top of the coil core that can stop it closing properly. When you are sure it is pulling down as far as it can check the two contacts are firmly closed. That may need some judicious bending to ensure that both touch at the same time and break at the same time.
Also treat every electric connector with DeoxIT from Caig Laboratories.
Regards,
K-BIKE

Thank you both. All the current questions are answered. I now have a 12V tender (staying at about 12.8V) and I will fix the relay or replace it now that I am sure it was not working properly.

The DeoxIT - I put it directly on the area the connect? OK, will do.

I'll also check out the fuel pump - good to know.

UPDATE on Starter relay. No dice.

Today I put my old STARTER RELAY in that I tried to fix myself by filing the 1 bad point a bit to make contact again.
It did not start.

What did happen was:
a. when I press the starter button the headlight does dim and the engine turns over.
b. when I release the starter button I hear a "hissing" sound that does not sound wrong.

Is the hissing sound the fuel pump and if so is that an indication that my fuel pump is fine? (oh please please)
and if so should I assume that my starter relay fix just was not good enough and I should try a new starter relay before I try anything else?

Note- I should also add that my bike had a full tune up and once over by a very good mechanic in Carol Gardens just last November. That same mechanic saw my bike 2 hours after it first stalled and was kind enough to give me his opinion of what was wrong on the spot.
He was very convinced that the problem was Low Voltage in the battery that lead to a bad starter relay.

At the time I didn't realize i was charging my battery on a 6V battery tender - I've since corrected that but Tom (the mechanic) was right on the low voltage.

Again - should I just invest in a new starter relay before i do anything else? Hate to admit it but even the $50 for that is a stretch at the moment.

Hey Jr,

Here is a $50 answer.
If your starter turns the engine over, you are OK. I applied the same cleaning treatment on the starter relay of my K75 and it's still working after 6 or 7 years.
The hissing can be and certainly is the fuel pump. One quick way to see if the pump is working is to open the tank's fuel cap an push the starter button. You should be able to see the gas moving in the tank (The pressure relief valve on the back of the throttle body should send the gas back to the tank). The other way is to pull the hose from the tank and push the starter button. You should have a container to catch this gas as you don't want to start a fire.
Having flow from the fuel pump doesn't insure that you have a good pressure. In order to measure the pressure you should put a gauge.
Have a look at the EFI troubleshooting page. There is some pictures at the bottom of the page.

Bert

Cool - thank you.
So my plan is:
I've ordered a new starter relay and battery.
I'll install both Monday and if the bike starts GREAT, if it does not I'll look in the tank to see if fuel is moving.

If it does start I will learn to take off and put on the fairing quickly and learn to clean the starter asap to avoid future problems.

Fingers crossed,
JR

Don't forget, use fresh fuel and if the plugs are wet it will not start, you will need to dry them, clear the fuel out of the cylinders and put the plugs back in and then start. That's assuming you have been getting injection.
Regards,
K-BIKE

FRUSTRATION.
I installed the new battery and starter relay today.
No change - still won't start.
I can't say with any authority but it really seems like the engine just is not getting any gas.

I'm going to try to find the links for "HOW TO" check to see if the fuel pump is pumping (I am pretty sure I hear it working) but I've never done that before and if it's the fuel injectors I might really be in trouble as I don't feel very confident tackling that job alone.

Today I just began to take the fairing off to get to the relays and gas tank.

I'm just venting - all you guys have been super helpful, thanks for that.
I'll read back through the posts and see what I can try next.
-JR

K-bike's suggestion in the post above may be easiest to tackle at this point, before removing the fairing. Remove the decorative plate covering the spark plugs, remove one spark plug wire and then remove the plug. If the plug is wet, it means that the engine is getting gas. Since it is turining over and you have confirmed that the engine is getting gas, then concentrate on the coils and ignition system. If the plugs are dry, then your assumption that the fuel supply / injection system might be at fault has more creadence.

I would tend to think that your problems might be related to electrics rather than fuel just because you mentioned that the bike was operational before being stored and suddenly after a hyatis, the bike is failing to start. It points to corrosion or broken wires somewhere.

Hi jr
I'm a novice here but had a similar problem early on. Undo the earth wire attached to the frame, mine had gunk all under the small washer. I cleaned it off and the patch on the frame, with emery, contact cleaner. Then it fired up first go. Then I had blocked injectors. Then I kicked my dog.
RT

Hi Robert -
I pulled all the plugs, cleaned them all and checked the gap. None were wet and to be honest they all looked almost new. The bike was service last November so no surprise there.
The bike is on the same block as a highly respected BMW motorcycle mechanic.
I'm hoping if I take off the fairing & check everything I can he will take a look at it Monday for (with all luck) no more than an hours labor which is about all I have at the moment. As far as electronics I'm learning as fast as I can. A faulty Multi-Meter was my introduction...not the best start but going so far so good now.

RT - Earth wire... huh - that sounds so simple. I'll have to learn where the heck it is and do the same tomorrow.
Good thing my dog has passed on. 160lb Akita might bite me back, or worse emasculate me further by not noticing the kick at all.

OHHHH!!!! I just reread the Spark Plug Wet suggestion. I checked them after it sat for a day. What I believe you mean is: "try starting the bike and then check the plugs right after." Right? and by wet you mean literally I'll see moisture on them ad I would assume smell gas."

OK - not I think I get it.

NOw I'll just look up where and what the coils do. OH FUN FUN JOY.

That's right. You want to check that the injectors are spraying gas into the cylinders. If so, then you can be assured that the engine would start if it gets spark. That's the next bit. Since you have the plug wire off, using a screwdriver bridge the spark plug wire you've just removed and create a small spark gap to the engine block. Crank the engine and see if you get a spark across the gap. If not, you have ignition problems. If so, then you'll have to delve deeper into the problem (or ask your mechanic for help).

Update - April 3, 2011.

Spark yes - I checked for a spark with the spark plug wires. There was a spark and I was mildly electrocuted.
Plugs dry - After trying to start it for about 15 seconds I checked the plugs and they were dry.

Gas NO - When I pulled the hose from the fuel rail and tried to start the bike no gas came out of the hose that I marked A in the 2nd photo.
(The Hose I pulled was from the rear stub under the gas tank on the drivers left that goes almost straight down to the rail - arrows pointing to it in pictures.)

As I do hear the fuel pump when I start the bike, if we assume the pump does work, where should I go now?
I saw mentioned it could be "simply" a bad connection somewhere. Should I pull the tank and try pulling all the relays, cleaning the connections, and go from there?

Oh. And I bought a new $10 Multi-meter. This one WORKS!! What a difference. (my last one was about 25% off)

My guess is that your problem is fuel starvation and not electrical. What you have done is disconnect the primary fuel line leading to the injector rail. Fuel delivery is a closed system; fuel is delivered from the pump through the fuel filter and into the injectors via that line you disconnected, continues through the fuel pressure regulator and back to the tank.

Since you disconnected the fuel line nearly at the source, you have isolated the problem to one of only a few components in the fuel delivery system. You can eliminate the fuel injectors, fuel regulator and associated lines for the moment as they do not contribute to your problem (yet).

Either your fuel pump is mechanically bad or the fuel filter in the tank is blocked or there is possibly a hose loose in the tank and your engine is not getting gas. Have a boo in the tank and check the hose connections to make sure they are secure. Remove the fuel filter while you're in there and replace it unless you are absolutely certain it is relatively new. Any one of the following filters is a suitable substitute for the BMW original:
Deutsch "FF424"
Fram G3802 (Ford Mustang 4.6L V6)
Napa Gold 3032
Triumph T1240850
AC GF61
BMW 16 14 325 859
Fleetguard FF149
KKnecht Mahle KL145
Motorcraft FG-2
Perolator F20011
Wix 33032
If, after all that, things seem kosher, then possibly it's time to pull the fuel pump and check it out on the bench. It might be clogged.

thats a nice find jr .......its good to narrow things down ....i suspect you will be cleaning out the tank ..and scrubbing it up before you put in the new filter .....the bosch pump is susceptible to small bits of gunge from rubber ,,, stale gummy fuel etc ....seiing that you have noise from it ...(good sign) i suggest a good flush with new fuel ....check all the rubbers inside ,,,the fuel filter gause at the bottom of the pump and replace anything that looks dodgy ...crumbly ,,,and then put in a new fuel filter .hoses etc ..dont forget the breather hose from the bottom of the fuel pump filter (1/4 inch id)....mine had fallen to bits ,,,and unluckilly siezed the pump solid with little flakes of dodgy rubber

please chose hoses rated for full imersion in fuel ...as most of the fuel lines you can buy are only external use with fuel running inside a special layer of rubber compound ,,the outside is not rated for fuel at all ...... good luck !!!!!

You'll need fuel hose with SAE 30R10 printed on it. This is the stuff that's used for full immersion.

The proper, full immersion fuel hose is surprisingly difficult to find in spite of common usage in cars these past few years...I bought some in a coupla metres length from the 'Bins just to have it around.

I looked today for that hose with no luck but being in NYC I hope that my location gives me SOME advantage.
I plan to pull the tank off tomorrow. Empty it. Check the vent hole/line (?) and fuel filter and hoses. A general clean all around and fresh gas.

Although it sounds like a dangerous idea if I were to pour gas directly from a Gas Can into the hose that goes into the speed rail would the bike theoretically run if nothing else was wrong?

Also - I have an extra battery. Is there a way to safely connect the fuel pump to a battery just to see if it is pumping gas? Away from the bike that is.

I would like to do more work at once but I have to ride a bicycle about 2 miles to where my K100LT is parked. A little extra challenge.

the answe is .........no ....sorry jr ...you would need to preasure the system to 32lbs first ...required for the injectors to inject into the valve / intake manifold ......running the pump out of the fuel is a no no as well ....they require the cooling etc from the fuel passing through it ....but if you wanted to hook up the batery to the pump for a few seconds it would probably be ok .....maybe if you had it sitting in a tub of "clean fuel" and solid connections to the power terminals ie (:definately no arcing ) you could test it so see if it pumps fuel .....might be a good idea to have a bit of hose on it to circulate the fuel back into the container insted of a fountain of fuel covering everything ...safety first ....please

Jr, You can momentarily apply 12V to the pump from the tank's electrical plug to test the pump's operation. There should be four connections on the plug. The Brown and Green/White wires are for the pump. Use a fused line (10A) and connect the battery negative to Brown and battery positive to Green/White. The pump should run if it is not defective. Follow charlie99's suggestion of recirculating the fuel back into the tank or catch it in another container. Be very careful of fumes and sparks in the vincinity of such fumes; maybe test in the open air or in the open garage door.

Maam, is the computer plugged in?

OK - so I've been out riding to avoid embarrassment.

Umm, so yeah - I was out of gas. I was trying to come up with a funny way to say it but - oops, there it is.
I rocked the bike back and forth and heard liquid. I peaked through the tiny little hole and thought I saw gas. I DID smell gas and the gauge said I had 1/4 tank.

I removed the 4 screws in the cap to take it off the tank to check the filter and hoses in the tank. I was surprised how clean the inside of the tank was and how new everything looked. That was about a 2 second thought, then it hit me. 'Why can I see everything so clearly...? What's missing...? NO, no no no."

Yes. 1 gallon later it started after 2 seconds on the starter and has run perfectly since. #&$*)%UQ_#*()$@9‡°®™ªº90√ Yeah.

Bike has been running perfectly. Got from Park Slope Brooklyn to 34st in 16 minutes this morning and wow easy (I am normally the slow guy). I've met my neighbor who has a new BMW 1200 but had owned k100r a while back, and 3 other people on my block who also covet my bike and used to be K100 owners.

Ok. Hope my sharing made you smile.
A little red,
JR

That's something I'd do!

Glad I'm not the only one.

All's well that ends well!

woohoo jr ...thank hevens for small mercies huh ?

cheers mate

Good you're back on the road!! I guess we all have our "Homer Simpson Moments" from time to time.

Lmbo I am sitting here reading about all the possibilities I may have to go thru with my k100 I am trying to get. Spark, check, starter check.fuel, yeh should be.. Bueller, Bueller? Where is Bueller?

Ahhahahahahahah that's never happened to me..
I had a 91 GMC truck, always did the maintainance thing, thought I had a fuel filter go out on me.. Thought I was out of gas, so what did I do? I filled the sucker up! All 21 gallons worth and then checked the filter... Dry as a bone.. Which meant I had a bad pump... ANyone have an idea what 21 gallons plus a tank weighs? Yup. Way too much.. Ended up using a forklift to lift the bed off.

Yes the story is good and I am glad you got it fixed. You guys rock..