K100 Engine Just Quit

[kris]

90km/ 55 miles into a perfect ride. Bike was running great. Was doing about 50kmh/ 30mph and went to throttle up and the bike simply died. No sputter, no strange noises. Tried cranking but no start. All lights on. Fuel pump pressurizes. Starter turns just fine. Let the bike cool for a bit (after speaking with the Mighty Gryphon....thanks Jim!) but still no go. I get towed back home. Days later I have a look. Thought I'd attempt a start before digging in to troubleshooting. Bike starts and runs poorly then quits. Engine is flooded - likely still from 4-5 days ago. Pulled the plugs. They are wet but look OK - number 4 (rear-most) really wet. Ground is good. Battery is good. Terminals are clean. 4-pin looks good. Inside the tank all fuel lines are connected and appear to be solid. Any ideas? Has anyone experienced something like this before? Yes, I did do some research but didn't see anything definitive on this set of circumstances. Thanks in advance for any advice!

PS - Gryph mentioned the temp sensor. That connection is good. And the sensor is new (2 months). Absolutely no issues or telltales before this episode

[beemuker]

Had an issue with my 1100 which turned out to be a bad connection in my ignition switch but everything would go out just like shutting the switch off yours is obviously a different issue good luck with it. There are some good troubleshooting flow charts on the site.

[daveson]

After a try at starting remove the vacuum hose from cylinder  four throttle body. It should be dry, if wet with fuel you need another fuel pressure regulator.

Actually before that remove cylinder four spark plug and the coil earth's, and beware that fuel might shoot out at cranking. Then replace it.

Actually before any of that, just remove the hose and see if it's damp. If it's damp don't just crank it, you could bend the con rod.

[The Mighty Gryphon]

What is the resistance between pins 10 and 13 on the big ECU connector?  Should be around 2500 ohms.

Also, while the connector is off, pull the ECU out of the bike and connect it.  Then try to start the bike again.  It's possible that the connector is hanging up on the frame tubes and not being connected properly.

[kris]

Thanks Gryph and Daveson. She is running now. I didn't see your two posts until after the work had been done.

Pulled the plugs - they weren't bad but cleaned and gapped 'em. Pulled and reseated spark leads at the coils. Cleaned battery terminals and topped up battery on charger. Cleaned bell housing and main frame ground. Pulled connectors on 90 percent of the wires under the tank. DEOXITed everything. Dried out the cylinders. Checked fuel pump lines. Pulled and reseated electronic ignition plug, obviously the computer plug. Put it back together and she reluctantly flashed after a number of cranks and then ran really nicely for 10 minutes. I will take her out locally for some close-to-home trips and see how she does. Not being able to pin down a specific cause casts a shadow on her reliability at this point but maybe I'll get lucky as a result of the above. If she kacks out again I'll let y'all know and I'll have to dig in deeper or call my mechanic. But I will check out both your suggestions, Gryph and Daveson, and see if that shows anything. Thanks again.

PS - getting back under the tank and pulling her covers underscored how well these machines were built - this girl is always garaged and has a pretty good life so not challenged in that regard (corrosion, constant moisture) - her gizzards clean up nicely - the quality is still evident!

[kris]

Daveson, just checked the vacuum hose on 4 and it appears to be bone dry. Thanks

[frankenduck]

Sudden death can be caused by a flaky ignition switch.

[beemuker]

Sudden death can be caused by a flaky ignition switch.

true, but in the poster's case his lights stay on, wouldn't everything turn off if it's the switch?

[Laitch]

It could be time to do the Hall sensor test described in the troubleshooting guide available as a PDF link at the end of this post, Kris. It doesn't take much takedown effort. Use a 12V LED.

[frankenduck]

It could be time to do the Hall sensor test described in the troubleshooting guide available as a PDF link at the end of this post, Kris. It doesn't take much takedown effort. Use a 12V LED.

Wouldn't restart even after it had cooled down.  Typically a failing HES will run again after cooling.

[Laitch]

Typically a failing HES will run again after cooling.

Sometimes, circumstance will fail to meet expectations.   

[alexg]

Hi:
have you checked the big plug to the engine computer under the seat, over the battery. Mine was loose, finally disconnected and the bike died w/o any previous warning.

Just a simple try.

Alex

[kris]

Thank you, gentlemen. Have been off the job for a couple of days. My temp sensor resistance readings are off by quite a bit. I am going to test everything again with another multimeter to see if there is a problem with my meter. Otherwise, it'll be a fresh temp sensor (and not one of the units from China...which is what I put in) and I will trace/ test the wire to see what might be causing the high resistance readings. If that all checks out I will go to the HES. Laitch, thanks for the info on that one. Frankenduck, my starter/kill switch was taken apart 1-2 years ago (time flies) and it checked out just fine as far as I could tell. I will keep you posted in order that the experiential troubleshooting and home repair guide builds!

Cheers!

[kris]

I told you I would update this situation so here it is. It appears that the replacement temperature sensor from China is faulty. It may have been OK at inception but the readings I got off it are way off (on the multimeter). This unit, under light use, didn't last more than a few months. Put the old Bosch back in - its readings were good. I was taking the readings off the Bosch incorrectly with my multimeter and that caused me to think it was faulty and to replace it. The situation was illumuminated and correction taken from the musings and suggestions of The Might Gryphon! Thanks Jim. His first instinct told him it might be the sensor.  It's early in the game yet and Heinz has yet to prove herself on the long haul but I'm hoping this sensor was the cause of the flooding and subsequent engine shutdown. The cool down at roadside wasn't more than 20-30 minutes before the tow truck arrived and I doubt that's long enough to clear a flooded engine.

FWIW, I did buy a replacement sensor. It is a "Blue Streak" unit - number TX39. This company flies under the old Standard Motor Products brand (US), or operates alongside it, and SMP is now, too, under the Intermotor group of  companies. I mention this because it can be a little confusing as to where to search for an alternate unit/ brand at what might be a better price point. The Blue Streak unit is manufactured in Spain. Further, the Bosch sensor unit number from my bike is 0280 130 032.

My two cents....

[frankenduck]

The cool down at roadside wasn't more than 20-30 minutes before the tow truck arrived and I doubt that's long enough to clear a flooded engine.

For a really flooded engine you probably need to pull the spark plugs and use a heat gun (or time) to evaporate the fuel.

On my 86 K100 a previous owner or wrench had left the clip off of the temp sensor and the connector just fell off while riding. With infinite resistance so much gas was being pumped that it was making a puddle of gas on the ground where the headers meet the exhaust collector when I tried to restart it.

Bosch 0280130032 is superseded by Bosch 0280130069.

[kris]

Thanks Frankenduck. And, yes, I had some fuel leak out of my headers when I tried my restart at home. Kinda surprised me. No heat gun with me and no tools at time of failure. Wouldn't have been worth getting taken out on the side of a 2-lane rural highway in any event!

Cheers!

[The Mighty Gryphon]

Good to hear you're back up and running.

Probably wouldn't have done any good to clear the excess fuel.  As soon as you tried to start again with the funky temperature sensor the engine would have flooded again anyway.  BTW, I've had good luck clearing a flooded engine by unplugging the "tank" electrical connector to disable the fuel pump and cranking the engine until it blows out the excess fuel and starts.  It usually only takes about 10-15 seconds.