Engine dies on the run. Wait a few minutes, and it runs again. Likely suspects?

[bizzaro]

 I am trying to get ready for my annual road trip with my brother on Monday.

So on the run, when the engine has warmed up, not distance relative, my 94K1100LT starts to choke and sputter then dies.  It quits within a few hundred yards of the onset of the symptoms.  If I sit for a minute and poke around.  It fires up again and drives normal.....................sometimes it does not recur for a long time. Others it will happen again in a few miles, but  it will always get me home....so far.  I thought I found the problem the other day as the fuel pump connection seemed wonky. Nope.  Cleaned it up and it still happens. 

So the last time it happened I proceeded to eliminate the source and find out WTF was going on on the roadside.  Pressure in fuel line was good, after it has died. Spark was strong after it quit.  NO telling if they were both up to snuff when it was quitting on the go. Always happens when it is warm, so far. Though I have noticed that it isn't started as quickly as it did last year. 

Things I have done since last year when this started happening.  It has gotten much worse:

1.New fuel filter and and quick inspection of fuel tank.
2.Checked tank cap assembly for correctness.
3.new plugs
4.compression test.
5.fuel pressure via visible strong flow out of fuel line. Note: I have installed a longer than normal hose so I can slide back the tank and not
   have to disconnect it.
6.Plug lead wire check by viewing for stray (lightning) sparks at night.
7.Throttle body sync
8.air leaks in and around the throttle bodies/air intake/crankcase breather

I may have done other things to try and fix this. this is what I can recollect.

So I am going to next check:
1. air leaks in and around the throttle bodies again.  I will use the propane test. 
2. adjust the TPS. I will use the click test.(It does not click now)  Can this actually shut a bike down on the run? Isn't it for idling?
3. Check compression. 
4. Empty and clean tank.

This is a quick review as I am running out of time to get it road ready for my trip.  My options are to get it fixed, borrow my sister in laws Suzuki  :mbird ,  or buy an ST1100 so I can have a running bike to drive to my local BMW dealer and get parts to fix my *%*&$#$$ indestructible K bike. (can ya taste the bitterness?)

[Laitch]

. . . or buy an ST100 so I can have a running bike to drive to my local BMW dealer and get parts to fix my *%*&$#$$ indestructible K bike.

Check the 4-pin fuel pump plug under the tank for tight fit and corrosion. While you're there check the ignition switch plug for the same conditions. Check the ignition switch for corrosion. These are less complex procedures to do first.

Is that the ST1100 up in St. Albans? Not too inspiring.

00p0p_vo53I1zjKh_600x450.jpg (34.93 kB . 337x450 - viewed 646 times)
I'd prefer this FJR down near Rutland or this PC800 over in NH.

00g0g_6p8GDQundjN_600x450.jpg (38.74 kB . 450x450 - viewed 645 times)

The PC always had an attraction for me because the fairing makes messing with it so inconvenient, it's liable to run better. :giggles

At the end of the day, consider the old maxim. Purchase in haste; repent at leisure.

[jakgieger]

Possibly this or that damned connection for fuel pump????

[Snowman]

Fuel tank venting problem? The volume of the fuel taken from the tank while its running is not being replaced with air. Next time it happens just open the fuel cap, see if it starts.

[thecableguy]

Disassemble and clean the contacts in the ignition switch.  Intermittent contacts here can cause all sorts of odd symptoms.  Mine was exhibiting a similar failure and cleaning the ignition switch cured it.


Of course YMMV...


Good Luck!
Jim

[bizzaro]

Thanks all.
So there is a four pin connection(hard wired?) under the tank as well Laitch. The one I worked on is connected by wires and is usually stuffed under the tank. I am really suspicious of the fuel pump connections.  With the key on and the bike not running the other day I could wiggle the wires and hear the pump kick in and out.  So I was pretty sure that I found the problem and cleaned it up.  That didn't fix it, nor have I been able to repeat the pump going on and off since I cleaned up the connection.  Even with the key on, unplug and replug the connection? I haven't really looked at the ignition switch. I have also cleaned up the kill switch now that you remind me. 

The ST1100 in St. Albans, yes. And there is one in Barre as well.  Newer and less miles.

Man that PC800 is one ugly P O S! :mbird

"Purchase in haste; repent at leisure."    Thanks for that one. I am feeling the pressure! No hasty decisions.

[bizzaro]

Jack...shit, right hall effect sensor....I  read that last year, and forgot about it.

Snowman....tank cap is assembled correctly.  I will throw my spare key in the tank cap and pop it on the run next time it starts to act up.

I will clean up the ignition. Can I cheat and just squirt it with electric cleaner?

[Laitch]

Can I cheat and just squirt it with electric cleaner?

If you're going to cheat, why waste the cleaner? Try reiki on it. Here are some instructions anyway. The condition of the wiring to your pump is suspicious and should be analyzed for integrity of its connections. How about posting a photo of that array while you're resting?

[BrickMW]

I had the same symptoms years ago... I switched to non-ethanol gas and it hasn't happened since. (knock on wood) Although, I did remove the tank to dump the old fuel, so it could have also been the 4-pin and I accidentally fixed it by excercising the connector. :dunno

[wally.fisher]

I am trying to get ready for my annual road trip with my brother on Monday.

So on the run, when the engine has warmed up, not distance relative, my 94K1100LT starts to choke and sputter then dies.  It quits within a few hundred yards of the onset of the symtoms.  If I sit for a minute and poke around.  It fires up again and drives normal.....................sometimes it does not recur for a long time. Others it will happen again in a few miles, but  it will always get me home....so far.  I thought I found the problem the other day as the fuel pump connection seemed wonky. Nope.  Cleaned it up and it still happens. 

So the last time it happened I proceeded to eliminate the source and find out WTF was going on on the roadside.  Pressure in fuel line was good, after it has died. Spark was strong after it quit.  NO telling if they were both up to snuff when it was quitting on the go. Always happens when it is warm, so far. Though I have noticed that it isn't started as quickly as it did last year. 

Things I have done since last year when this started happening.  It has gotten much worse:

1.New fuel filter and and quick inspection of fuel tank.
2.Checked tank cap assembly for correctness.
3.new plugs
4.compression test.
5.fuel pressure via visible strong flow out of fuel line. Note: I have installed a longer than normal hose so I can slide back the tank and not
   have to disconnect it.
6.Plug lead wire check by viewing for stray (lightning) sparks at night.
7.Throttle body sync
8.air leaks in and around the throttle bodies/air intake/crankcase breather

I may have done other things to try and fix this. this is what I can recollect.

So I am going to next check:
1. air leaks in and around the throttle bodies again.  I will use the propane test. 
2. adjust the TPS. I will use the click test.(It does not click now)  Can this actually shut a bike down on the run? Isn't it for idling?
3. Check compression. 
4. Empty and clean tank.

This is a quick review as I am running out of time to get it road ready for my trip.  My options are to get it fixed, borrow my sister in laws Suzuki  :mbird ,  or buy an ST1100 so I can have a running bike to drive to my local BMW dealer and get parts to fix my *%*&$#$$ indestructible K bike. (can ya taste the bitterness?)

Cannot do a click test on a k1100 tps, it must be set using your multimeter, the setting should be .38 with ignition on, not started.


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[Martin]

Try wriggling the infamous 4 pin connector while the bike is running and listen to the pump. If it I faulty don't worry about trying bodge it up replace it with a new waterproof connector, Tandy should have one.
When it does die have you pulled the spark plugs if so what is the condition. The Honorable Minister had a problem once with her car cutting out when hot, I was away so she took it to an auto electrician who could not find the problem. I came home and found the problem by getting to heat up and then cut out. I then packed crushed ice wrapped in a cloth around various electrical components while she tried to get it to start. When I cooled down the crank sensor it fired right up. In the end I could get it to cut out and then spray it with a hose and it would fire up again. Spray coolant would be a bit more sophisticated but hey you use what you have got.
Regards Martin.

[bizzaro]

Here ya go Laitch....  Confirmation

[wally.fisher]

Use a wire brush to clean the male n female connections,
.


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[Martin]

Even cleaned they can still have intermittent connections, infected with Gremlins from the Black Forest.  Do the wiggle and listen while running test.
Regards Martin,

[The Mighty Gryphon]

Even if it isn't the problem it is a good thing to clean the ignition switch.  The design is marginal as far as contact pressure so it takes very little to interfere with the electrical functioning.  I don't think there are any short cuts to getting it right.

[Scott_]

Something that no one has mentioned yet... use some spray contact cleaner on the MOTRONIC multi-pin connector.
I've had that connector give me fuel pump problems on my '97. Cleaned and re-seated a couple of times, and all has been good since.

What other indicators are you having besides the engine dying... is the headlamp going out, are the cluster lamps going out, gauges going to full left off positions.... Where I'm going here, like some other have mentioned, the ignition switch contacts, but it could also be a broken/damaged power wire to the ignition switch.

[Elipten]

Better get a can or two of dexoit


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[bizzaro]

Thanks to everyone.  I am working though it all. I will be out and about to today road testing.  Of course the real test will be on the road trip next week! If I find a "definitive" answer I will surely post it. That may be hard to nail down as I am doing multiple kinds of maintenance to eliminate the the problem?  Fuel tank is cleaner than clean. Gas cap and relief tube are clean and clear. Working through the all electrical contacts/connections with cleaner etc. will check HES later today.  I am hoping for some heat today as it does seem to be heat related/exacerbated.  Which can affect the gas tank, electric connections, and the engine and its components. Well that sure narrows it down! :hehehe :hehehe :hehehe

[White Dog]

While you have the 4 pin connector apart, notice that your female ports are smaller than their male counterparts.  What I had to do to get my fuel pump to run when it was supposed to, was to slightly flatten the female holes so the male pins would touch.

[bizzaro]

The holes in the female part of the connector are split in four places and sprung in toward the pin for a positive connection. Not sure what the tech term is. Crushing the connector to get good contact would be a last resort. No turning back after that (may as well replace it)and who knows how long it may last?  I shaved the top of my female connector to get better penetration, from the pins.

[White Dog]

I should have said the female ports were larger than the male pins.  By slightly flattening the female ports, the male pins fit tighter, thus no worries with wiggly pins.

A 4 pin trailer connector will work better if you are good at soldering small wires.

[bizzaro]

I should have said the female ports were larger than the male pins.  By slightly flattening the female ports, the male pins fit tighter, thus no worries with wiggly pins.

Yes, I assumed you ah.......got your wires crossed! :hehehe . But the reason the holes are larger is because of the design of the connection. It is like an inverted banana plug.

[Al]

My 1990 K75 did a die and live again routine on me. When the bike was hot-especially if was heat soaked after a ride- it would run about 2-5 minutes and then cut out. Let it sit a few minutes and it would run fine until the next time. Sometimes it would do it a couple time in a month and other times i would happen several times a day. At the Billings rally it died completely. WOuldn't start first thin in the morning. I had suspected the Hall sensor so I bought 4 of them for $36 from a Chinese lady in Germany. As opposed to $500 from BMW. It has been running fine ever since. I now carry the 2 spare with me just in case. I also picked up a burned out unit so that I can just do the old switcher instead of soldering it on the road.


Oh, except one  or two incidents when it died after sitting. I was immediately thinking it was the Hall sensors but turned out to be the kill switch. The plastic shaft develops a ring worn on it which prevents it from sliding down into the contacts. On the MOA site someone showed how he took some very fine sand paper and smoother that ring away resulting in no problems henceforth.


I'm not impressed with eh quality of BMW K bike switches, The seem kind of mickey mouse to me.


Not sure if any of these help but maybe someone will get some use from the info.

[Motorhobo]

I was immediately thinking it was the Hall sensors but turned out to be the kill switch. The plastic shaft develops a ring worn on it which prevents it from sliding down into the contacts. On the MOA site someone showed how he took some very fine sand paper and smoother that ring away resulting in no problems henceforth.


I'm not impressed with eh quality of BMW K bike switches, The seem kind of mickey mouse to me.


Not sure if any of these help but maybe someone will get some use from the info.

Same answer as with the other post --

I also had exactly the same issue with the start button -- I think the electrical contacts inside the combo switches are a hugely underrated cause of problems. For me, it was with a bike that has seen a lot of Seattle rain from the time I acquired it in 2000 to the time the corrosion in there started interfering with the contact in 2009. So that's 10 years of neglect -- which is probably a lot better than a Mickey Mousey switch would have fared. So -- not sure I agree with the quality assessment -- you have to do the maintenance on 20+ year old stuff, and those switches are parts that never see the light of day so people assume they're bulletproof -- they're not.

Anyway, I ended up tearing the thing apart trying to bridge past the start button so I could at least push-start it (it was a sidecar rig). The switch was destroyed but I was able to push start it avoiding a costly tow. I got a new used combo switch from kbikeparts.com, no problem since, and I don't live in Seattle anymore so less rain gets in there...

BTW -- all power goes thru the right side combo switch. If it's bad, the bike will cut out and that might be the last place you'd look for a problem, but it shouldn't be.

[BlitzenGruv]

I'm not impressed with eh quality of BMW K bike switches, The seem kind of mickey mouse to me.

You ought to try rebuilding the Lucas switches on '70s British bikes. THOSE are really Mickey Mouse.  :hehehe