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1Back to top Go down   Difficulty starting 1989 K100RS Empty Difficulty starting 1989 K100RS on Fri Jul 24, 2020 5:27 pm

TimK100

TimK100
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Out of the blue, the bike doesn't want to start. Once I hit the button there is an initial pop, but then it continues to crank and crank. If I hold the throttle wide open and crank it for a good few seconds it fires up and smells like it's flooded. I noticed a small gas puddle near the center stand. Once I get it going it seems to run fine. As soon as I shut it off and try to restart I get the same problem. It's my daily rider for the past 9 years and there was no indication of any problems. Yesterday it fired like a top, today nothing but trouble. I'm just not very good at troubleshooting, I was hoping somebody might have some insight on what it might be.

    

2Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Fri Jul 24, 2020 6:02 pm

MartinW

MartinW
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Check the temperature sensor values and check if the sensor plug is clean and has a good connection.
Regards Martin.


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K75s Hybrid
    

3Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Fri Jul 24, 2020 9:30 pm

TimK100

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I will check that, thanks. Would that affect it from a cold and warm start?

    

4Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Sat Jul 25, 2020 1:00 am

MartinW

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Yep it's one of the known sources of flooding. Another one is a sticky injector/s that doesn't fully close on shut down.
Regards Martin.


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K75s Hybrid
    

5Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Sat Jul 25, 2020 6:21 pm

TimK100

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Thanks for the input, Martin. That will give me something to work on in the coming week.

    

6Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Sun Jul 26, 2020 6:52 pm

TimK100

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Well I have checked the temp sensor & plug voltage, they both seem to be working ok. Pulled all the injectors and checked them, they seem ok. I connected them back to the fuel rail and hit the ignition, they all seem to spray evenly and shut off all the same. Maybe somebody may have some other suggestions, I would sure appreciate it. I'm not sure where to go from here. I'm no mechanic but I do enjoy doing my own work and learning a thing or two in the process. It still floods when starting, fuel dripping out of the manifold after cranking for a bit.
Thanks for any input.

    

7Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Sun Jul 26, 2020 7:10 pm

StandardK

StandardK
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Is your start button intact and still “springy“? They don’t seem to be happy running when left in the depressed position...

Regard

Dan

    

8Back to top Go down   Difficulty starting 1989 K100RS Empty starting problem on Sun Jul 26, 2020 9:52 pm

daveyson

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Was the fuel spraying on and off, or a constant spray, I'm guessing on off.

You might have a blockage in the fuel return line, raising the pressure. With the fuel cap assembly removed, can you see fuel returning to the tank? There is a recent thread like that "another k100 running too rich"


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

9Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Sun Jul 26, 2020 10:19 pm

MartinW

MartinW
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A non OEM return has a tendency to crimp over where it goes into the tank. The OEM hose has the bends molded in. Cheap hose and hot weather makes the crimping over more probable.

Regards Martin.


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K75s Hybrid
    

10Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Fri Jul 31, 2020 3:18 pm

TimK100

TimK100
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Well, no luck yet. I did notice the vacuum line going to the FPR was somewhat dry and cracking, so I replaced that. Then I did a fuel pressure test. Even though it won't start, it was reading 39 or 40 psi, while it was cranking. I also tried disconnecting the idle switch and starting- no difference there either.  I really appreciate all of the help, but I may have to rely on professionals to figure this one out for me.

    

11Back to top Go down   Difficulty starting 1989 K100RS Empty No go on Fri Jul 31, 2020 6:29 pm

daveyson

daveyson
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Also you might have constantly open injectors, which is rare,  but easy to check.

Some people here (not me) are also professionals.

Did you check the return hose like Martin mentioned?

You might be able to get it going with the fuel pump electrical connection unplugged if constantly open, I guess the reading is high for this problem though.

While cranking, with a screwdriver to an injector and its handle to your ear you should hear the ticking sound of the injectors turning on and off.

Or while cranking, using a (12V) computer safe test lights clip on battery positive and probe to the loom of an injector plug,  the light should remain off at one pin,  and flash on/off at the other.

The pin that remains off would be power (positive to positive) The other pin (earth, as in the photo) should flash on and off.

Difficulty starting 1989 K100RS 04110



Last edited by daveyson on Sat Aug 01, 2020 3:14 am; edited 3 times in total (Reason for editing : edit for photo)


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

12Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Fri Jul 31, 2020 8:37 pm

gabriel

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Hi

What about the battery?
How old is your battery? Perhaps it’s time to replace?
Might have enough charge to turn the motor. But not enough for all the electrical systems.


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;BMW; 1984 BMW k100..frame number 6228?
    

13Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Fri Jul 31, 2020 9:46 pm

TimK100

TimK100
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I hadn't mentioned the hose to Martin as I didn't noticed it yet. I had pulled the fuel rail with the injectors connected and they all sprayed and shut off equally. Would a low battery cause it to flood?

    

14Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Fri Jul 31, 2020 9:52 pm

TimK100

TimK100
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I did not check the return hose yet. Would the fuel come back into the tank if it's not starting, only cranking? I also had replaced the spark plugs after realizing it had been a while since I did that.

    

15Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Fri Jul 31, 2020 9:55 pm

TimK100

TimK100
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A couple of years ago, I did have a low power battery that would crank quite a bit but not start the bike. A jump start fired it right up, so I replaced it. However I don't recall the flooding and fuel dripping underneath.

    

16Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Fri Jul 31, 2020 10:15 pm

TimK100

TimK100
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Also I didn't mean to infer that there were not professionals on this forum, I was only referring to myself and lack of knowledge. Sometimes I doubt myself testing these things, whether or not I'm doing it right.

    

17Back to top Go down   Difficulty starting 1989 K100RS Empty No go on Fri Jul 31, 2020 10:23 pm

daveyson

daveyson
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Fuel should return to the tank, even while cranking.

Multiple failed attempts to start could cause flooding, but fuel leaking out the headers seems an excessive amount.


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

18Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Fri Jul 31, 2020 10:31 pm

Point-Seven-five

Point-Seven-five
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Couple questions:

1. you mention checking the Temperature sensor voltage.  You should be checking resistance in ohms.  A cold engine should give a reading of 2500 ohms, at running temperature it should be about 250 ohms.

2.  what kind of spark plugs are in the engine?  KGK D7EA are good plugs, but have been known to cause problems if they don't have the "terminal nut" installed on the terminal where the plug wire connects.

3.  Have you pulled the spark plugs to see what the electrodes look like?  Are they sooty and black, wet, or normal tan/light brown?


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

19Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Fri Jul 31, 2020 11:01 pm

TimK100

TimK100
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I did check the resistance on the sensor. I probable meant to say I checked the plug for the sensor to make sure I didn't have a bad ground. I did just put in the NGK D7EA plugs, I added the terminal nut from another new set of plugs. The old plugs looked like a fairly normal wear.
I also wondered if anybody knows why I can't seem to see any of the photos that anybody has posted on the forum. They are all some blank image of a mountain.

    

20Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Sat Aug 01, 2020 12:21 am

gabriel

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Have a look at the technical guides located on the first page of the “how to” section of the forum.
I suggest clean and degrease all connectors including under the petrol tank. Unplug the ecu and ignition control unit and use the connector plug to check for continuity.
Check Ground points under petrol tank.
Do not apply a multimeter to the ecu and ignition units, only the connectors.
Use the technical manual to guide you.
Make certain your battery is in good condition

LE-JETRONIC-DIAGNOSIS-TEST-EQUIP



 Gabriel


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;BMW; 1984 BMW k100..frame number 6228?
    

21Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Sat Aug 01, 2020 12:38 am

gabriel

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Difficulty starting 1989 K100RS D63fc510


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;BMW; 1984 BMW k100..frame number 6228?
    

22Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Sat Aug 01, 2020 12:56 am

gabriel

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;BMW; 1984 BMW k100..frame number 6228?
    

23Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Sat Aug 01, 2020 2:00 pm

TimK100

TimK100
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Thanks Gabriel, I will look into that

    

24Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Sat Aug 01, 2020 11:07 pm

TimK100

TimK100
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OK so today I put the battery on charge while I got to work. I started with checking the ECU connection, it looked pretty clean, but i cleaned it anyway. Then, I removed the gas tank and removed the ignition control unit, checked the connections, and cleaned them. On the ICU connections, a few of the tabs looked a little dark while the others looked pretty shiny, so i cleaned them pretty thoroughly. Then I proceeded to remove the ground bolt under the tank with several wires connected to it, and thoroughly clean all of the connections and put it back together. Then I removed the air box to check the fuel return hose, which was not blocked up, but it did have some dry cracking, so I replaced it. After that I put the tank back on, the battery back in, made sure everything was connected, and thought "Well, here goes". I was actually fairly surprised when it fired right up. Sounded pretty smooth as well. I can't thank you guys enough for all of the help and suggestions. I wish I knew what the final solution was, but I won't linger on it too long, just happy it's up and running again.
Happy riding everybody! cheers

    

25Back to top Go down   Difficulty starting 1989 K100RS Empty Re: Difficulty starting 1989 K100RS on Sun Aug 02, 2020 12:50 pm

gabriel

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Well done!  Enjoy...l


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;BMW; 1984 BMW k100..frame number 6228?
    

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