What could be the problem if the bike will start and run, as long as the throttle and choke are not touched?
The bike starts OK, and idles perfectly, but when the throttle is moved, or the choke is moved to the top of the stop, it stops instantly.
Background: The ignition coils failed, (old brown type) eight months ago. I left the bike sit, and during that time the battery went flat. So, new Bosch coils were bought and intalled, and new battery fitted.
The coils were wired incorrectly the first time, with the red and blue wires interchanged. There was a fairly substantial backfire during that episode, but the error was corrected and the bike started. However, it now will not run beyond a nice even idle.
Any clues before I disassemble it?

Update:
1. I have tried starting it with the Throttle Postion Switch (TPS) both connected, and disconnected. No change.
2. I checked all the resistances with a Fluke digital multimeter and get the same resistances as mentioned on the troubleshooting starting post on http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm
Still researching.

I would be looking at the air flow meter.

Gundy wrote:I pulled the pump out today and what a mess. Bits of rubber everywhere I think I will replace the filter, pump and return line hose.
Gundy

It looks like your engine is starving for fuel.
If the bike has been sitting for 8 months, I would start to look a the fuel supply (pump and filter).

I was thinking of air flow meter too, robinm. I was hoping someone would know if there was some switch function that activated just off the bottom of the throttle travel. If I move the throttle off the lower stop, or push the choke lever up to the top stop, the engine stops.
CrazyFrog, the stop is too sharp and defined to be a bad fuel problem. I would imagine a fuel problem to be less defined than that problem I am having.
So, a switch function of some sort is the first suspect, but which switch? I suspected the lower (idle) TPS at first, but disconnecting it made no difference. If I am checking the air flow meter, what throttle function is initiated in the transition from the idle to the rev range managed by the airflow meter when the throttle moves just off the bottom stop?

I am also going to replace all the fuel and check the filter. The fuel pump sounds good and strong, and works when the ignition is turned on and the starter is pressed.
Thank you both for your responses.

Hi Peter,

No real switch to speak of other than what you disconnected but you mention it happens with the "choke" fully on but what about in between?

Do you still have the original throttle cable or the modified one. It was replaced for a reason but I can not recall what it was but I believe something electrical.

Original one has the adjuster some distance from the handlebar.

Regards,

Phil

If it stops that suddenly it would normally point to the transition from the running via the throttle switch to when the switch clicks off which it would do both when you twist the grip or use the Choke which is a fast idle control really not a choke it just cracks the throttle open a little bit. I suspect the air flow meter got damaged by the backfire. You need to see if it is intact and as it moves the resistance varies smoothly.
Regards,
K-BIKE

Peter,
Sounds like the lack of fuel pressure....however, don't go buying an expensive pump that you intend to be replacing, go here to my file sharing and download the replacement fuel pump.
http://www.4shared.com/account/dir/32417964/fca60d54/sharing.html?rnd=82
This is a copy from another K owner and I will be doing this if mine packs up. A cheap Ford pump will do it.
Ajays

Well, I agree with Peter in that a sudden stop does not indicate a lack of fuel. If the pump doesn't pump enough quantity (same with a dirty fuel filter) and you slowly open the throttle the bike starves slowly, not abruptly. I wonder if you've fried your ignition module with the wrongly connected coils, but then again you would not expect it to idle as well.
When you opened up the TPS were the connectors wet or corroded? Did you clean the connector? Otherwise it might be a wrongly seated ECU connector (did it lock?) or ECU problems (although rare). I feel that it is an electrical problem. Have you cleaned all your connectors??

Hi all. Thank you for your advice, I haven't forgotten you. I will be looking at the bike on Saturday 24 April 10, but will have to leave it for ten days after that. I am going to Beijing, and will start work in the bike on 7 May 10, when I get back.
I will report my findings on this site then.
I have removed the ECU from under the seat and tested it on a 1989 BMW K100 LT that I have. The ECU works perfectly, so that is not the problem.
I am going to test the air flow meter from the broken bike on the good bike when I get back, and see if that changes anything. I will go over it with the multimeter first.
Till then, ride safely.
PeterFG.
The problem still persists in that the bike will start if I don't touch the throttle or the "choke", (throttle advancer, really). Yes, it is starting cold and baulks a little, but the weather is warm here and it will eventually start, after a couple of attempts.
The moment I touch the hand throttle, it stops. I can move the "choke" up to the first stop OK, but if I push it into the top of the rotation, it stops. (The choke has a long travel, then a short push but will pop back travel at the top of the arc. That will stop the bike.)
I look forward to letting you all know what it was, when I find out what it was.

Interesting problem. I would also lean toward the air flow meter, test the resistance changes when you move the vane, of if you have one that definatley works swap it out and test it.

As for the TPS if you have removed it in the passed, often when replaced the switch isn't closed on no throttle, you should hear it click when you turn the throttle slightly, and then again on full throttle. If it idles when you disconnected it that tells the EFI you are part throttle.

But I think you have to cross off the air flow before moving on.

Hi Peter, I have just aquired a K100LT with exactly the same problem. I am following this thread with the hope that a remedy is found.

Hi evo1340,
Have you done all of the checks on the resistance of the sensors and the air flow sensor?
Regards,
K-BIKE

Sorry that i have not replied to the post i only collected the bike last weekend and this weekend was the first time i have had time to look at it. My problem has been sorted and yes it was the airflow meter that was to blame in a strange way. After removing the fairing it all became clear as to the problem. When the bike backfired it blew the intake pipe from the airbox off the manfold. Once this was replaced the bike fired up and ran as sweet as a nut. So yes the problem was no signal from the airflow meter, NO AIRFLOW NO READING!!!
Thanks to the forum for pointing me in the right directin.
Chris

evo1340 wrote:.... When the bike backfired it blew the intake pipe from the airbox off the manfold. Once this was replaced the bike fired up and ran as sweet as a nut. So yes the problem was no signal from the airflow meter, NO AIRFLOW NO READING!!!
Thanks to the forum for pointing me in the right directin.
Chris

So it ran a bit too lean. good to remove all intake leaks
Seriously, good to hear your problems are solved.

I had a friend with an R1100 which had exactly the same problem as you describe.
In the end if I remember correctly it turned out to be the crank sensor.