Author Topic: Sudden death  (Read 223 times)

Offline JPaganel

  • ^ Proficient Motobricker
  • Posts: 167
Sudden death
« on: June 12, 2019, 12:13:35 PM »
So, the Frankenbeemer up and quit about halfway to work this morning.

I was riding a gear lower than I normally would, pursuant to this conversation: http://www.motobrick.com/index.php/topic,12523.0.html

Going about 60. Suddenly engine shut off. No weird noises, or anything. Pulled over on the shoulder, cranked a bit. Crank, no start. I can hear the pump running in the tank, so that part is OK.

Once I manage transport it home, I'll check spark. Any other ideas?

  • Minnesnowta
  • 1986 K100RT, 1996 R1100RS

Offline volador

  • ^ Motobrick Curious
  • Posts: 66
Re: Sudden death
« Reply #1 on: June 12, 2019, 01:40:28 PM »
Starter Backspin

Starter Motor Cleaning Tutorial

Check your ground points: Left footpeg plate transmission ground and a frame ground wire connection on the left side of the center frame tube under the fuel tank
  • NYC
  • 1991 K100RS 1993 K75S ABS

Offline The Mighty Gryphon

  • ^ Quintessential Motobricker
  • Posts: 4398
Re: Sudden death
« Reply #2 on: June 12, 2019, 02:27:38 PM »
I am not all that conversant with the wiring schematic for the K100LT, but it could be an issue in the ignition or kill switch. 

A couple years ago, I had problems with my K75RT shutting down on me suddenly while riding.  In my case turning off the ignition and turning it on again brought back normal running most of the time.  Finally, the engine wouldn't start no matter what I did.  Disassembling the ignition and cleaning the internals brought back proper operation, and I haven't had any problems in the 30,000 miles since.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too
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Offline JPaganel

  • ^ Proficient Motobricker
  • Posts: 167
Re: Sudden death
« Reply #3 on: June 12, 2019, 04:18:18 PM »
Starter Backspin
Starter Motor Cleaning Tutorial
Check your ground points: Left footpeg plate transmission ground and a frame ground wire connection on the left side of the center frame tube under the fuel tank

Starter is fine - I can crank it till the battery dies.

Ground... That sounds like a maybe.

I am not all that conversant with the wiring schematic for the K100LT, but it could be an issue in the ignition or kill switch. 

A couple years ago, I had problems with my K75RT shutting down on me suddenly while riding.  In my case turning off the ignition and turning it on again brought back normal running most of the time.  Finally, the engine wouldn't start no matter what I did.  Disassembling the ignition and cleaning the internals brought back proper operation, and I haven't had any problems in the 30,000 miles since.

Ignition switch has been disassembled and completely cleaned/degreased last fall.  Kill switch was gone through about the same time. Not that they can't develop new problems. Or that wiring harness isn't at fault.

In hindsight, I should have tried flipping the kill switch a few times in case it was that... On all my other bikes kill switch would stop the engine, but let the starter crank.








  • Minnesnowta
  • 1986 K100RT, 1996 R1100RS

Offline Laitch

  • ^ Quintessential Motobricker
  • Posts: 6373
Re: Sudden death
« Reply #4 on: June 12, 2019, 05:33:18 PM »
You replaced fuel injectors and spark plugs last year. The engine was running well in October.

How have you checked for spark? How have you checked that the fuel pump is actually pumping all the way to the injector rail when it's running? Are the spark plugs wet or dry after starting is attempted?




  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline The Mighty Gryphon

  • ^ Quintessential Motobricker
  • Posts: 4398
Re: Sudden death
« Reply #5 on: June 12, 2019, 05:36:31 PM »
I suspect an electrical problem.  Fuel problems usually sputter before dying.  A sharp cutting off of the engine is normally electrical.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too

Offline Laitch

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  • Posts: 6373
Re: Sudden death
« Reply #6 on: June 12, 2019, 05:47:13 PM »
I suspect an electrical problem.
That was clear.
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline JPaganel

  • ^ Proficient Motobricker
  • Posts: 167
Re: Sudden death
« Reply #7 on: June 12, 2019, 06:26:05 PM »
You replaced fuel injectors and spark plugs last year. The engine was running well in October.
It was actually running well the last two months of daily use (with the exception of one or two heavy rain days) if you don't count occasional smoke clouds.

How have you checked for spark?
I haven't yet. Highway patrol around here frowns on roadside mechanic work on controlled access freeways.

How have you checked that the fuel pump is actually pumping all the way to the injector rail when it's running?
I tried to pinch the fuel hose. Felt like it had pressure, but that isn't necessarily reliable.

Kinda want to install a fuel pressure gauge now...


Are the spark plugs wet or dry after starting is attempted?
Dunno. Will find out after I trailer it home.
  • Minnesnowta
  • 1986 K100RT, 1996 R1100RS

Offline The Mighty Gryphon

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  • Posts: 4398
Re: Sudden death
« Reply #8 on: June 12, 2019, 10:30:20 PM »
f o r e   p i n

I was thinking that as well, but the O.P. said the pump was running. 
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too

Offline JPaganel

  • ^ Proficient Motobricker
  • Posts: 167
Re: Sudden death
« Reply #9 on: June 12, 2019, 11:34:52 PM »
Got the carcass home.

1. Not the kill switch - hitting that makes it not crank.

2. Used an inline spark tester and it blinked on #1 and #2 cylinders. Got spark.

3. The pump runs - verified by unplugging the connector. The sound goes away when I unplug it.

4. Tested injectors - ground at rest, power when cranking.

5. Pulled a plug after cranking - plug is dry.

6. Going with what Laitch said, pulled the hose from the fuel rail. 

Sonofabitch. A little dribble, then nothing.

Hose clamp inside the tank loosened and the hose popped off the pump. It was sucking air.  I guess because this happened at high RPM, the gas in the system got used up quickly.

Hose back on, back to running just fine. It's fixeded.

  • Minnesnowta
  • 1986 K100RT, 1996 R1100RS

Offline JPaganel

  • ^ Proficient Motobricker
  • Posts: 167
Re: Sudden death
« Reply #10 on: June 12, 2019, 11:53:14 PM »
greetings...

so it started after you messed with the fore pin...

ok... so there you go...

j o

I fixt that fore pin last fall, too. Taken apart, all four pins, cleaned all of them, re-insulated wires. Been all through that bastard.
  • Minnesnowta
  • 1986 K100RT, 1996 R1100RS

Offline Laitch

  • ^ Quintessential Motobricker
  • Posts: 6373
Re: Sudden death
« Reply #11 on: June 13, 2019, 12:11:55 AM »
Hose clamp inside the tank loosened and the hose popped off the pump. It was sucking air.  I guess because this happened at high RPM, the gas in the system got used up quickly.
Let's not get giddy with theory. It happened because the hose clamp wasn't tight and the hose fell off. It probably would have happened similarly even at low speed while you were stalking somebody. :giggles It's also too early for celebration. Head back to the freeway. Pack a lunch.
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline JPaganel

  • ^ Proficient Motobricker
  • Posts: 167
Re: Sudden death
« Reply #12 on: June 13, 2019, 10:18:15 AM »
Kinda want to install a fuel pressure gauge now...

Wow. I guess this is made just for us...
  • Minnesnowta
  • 1986 K100RT, 1996 R1100RS

Offline JPaganel

  • ^ Proficient Motobricker
  • Posts: 167
Re: Sudden death
« Reply #13 on: June 13, 2019, 11:54:34 AM »
Let's not get giddy with theory. It happened because the hose clamp wasn't tight and the hose fell off. It probably would have happened similarly even at low speed while you were stalking somebody. :giggles

Oh, I'm not theorizing why it happened. I'm only theorizing why it felt like a sudden cutoff of an electrical issue rather than a gradual sputter of a fuel problem.
  • Minnesnowta
  • 1986 K100RT, 1996 R1100RS

Offline The Mighty Gryphon

  • ^ Quintessential Motobricker
  • Posts: 4398
Re: Sudden death
« Reply #14 on: June 13, 2019, 12:04:20 PM »
Rapid depressurization of the rail.  Without any pressure no injection.  Not like the gradual loss of rail pressure, the drop in float bowl level or a piece of crap blocking an orifice.

I have to update my troubleshooting memory banks.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too

Offline Laitch

  • ^ Quintessential Motobricker
  • Posts: 6373
Re: Sudden death
« Reply #15 on: June 13, 2019, 12:53:59 PM »
I'm only theorizing why it felt like a sudden cutoff of an electrical issue rather than a gradual sputter of a fuel problem.
You're not in Kansas anymore, Dorothy, and where's Toto anyway? :giggles
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

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