K100LT stumbling and random stall.

[Fotocrazy]

Hi all. Broke down in Cambridge on A14 right on the centre reservation and had to get recovery home. The bike was bogging down before it cut out and and wouldn't restart. I have been experiencing stumbling of the engine for a few months now but has got worse over time. It has stalled a couple of times and did not restart till cooled. It hasn't been over heating so I put it down to the Hall effect sensor but yesterday I let it idle to get it nice and hot and the fan came on as normal. It didn't stutter or stall so that's the hall sensor suspicion out the window. The stumbling and stalling is very random. Today I changed the fuel filter in the tank. I put the new filter to my mouth and could blow through it but the old one seemed to be partially blocked as I was unable to create the same effect. Could this have been the fault? I have taken in out on a 30 mile ride after the filter swap and no problems at all but as I said, the problem was very random. The reason I ask is because I have a 400 mile ride coming up over the weekend and I'm a bit paranoid about braking down again and lost a bit of faith in the bike. Could the fuel filter be the problem. Thanks guy. I'm new to the forum and hope I am asking in the right area.  :falldown:

[johnny]

greetings fotocrazy...

welcome to motobrick.com...

if thats my motobrick... i would do this...

1... backspin starter maintenance...
2... clean under tank 4 pin connector...
3... clean motronic contacts...
4... clean the battery hot and all battery grounds...
5... make sure sparkplugs and sparkplug wires are tight...

give it a go... you may be pleasently surprized...


j o

[Fotocrazy]

Thanks Johnny for your reply. I did take a ride out today and all seemed fine until earlier when I has a pillion. Started and then died. The engine was cold. And would not restart. I'm going to get some electrical contact cleaner tomorrow and abuse it on all contacts. Bit odd as it's intermittent so as to your advise I will try this. The only problem is, I don't know how to remove the tank as I'm not very educated on this model and fear I will break something. I have seen this problem on other forums with no solution but will defiantly have a look. I've changed the grey box under the seat and the fuel filter. Could it be the hall sensor? I thought they become defective over time and become heat sensitive but the bike was cold. Start motor works fine and the plugs where changed a couple of months ago due to annual service. I pick my brain so much it hurt. I will have a look at electrical connections. Could it also be the fuel pump? I do hear it pressurising the system for a second or two but when all failed earlier I didn't check this. I'll have a mooch tomorrow.

[motodude]

I had a K100 that was sputtering when it was cold outside (I don't remember, maybe low 30's high 20's F).  I checked many things including the FI "computer".  Nothing seemed to fix it.  During my troubleshooting I noticed that the engine temp sensor was "off" by an order of magnitude but did "track" with engine temperature (resistence rose (or was it fell) as engine temp came up).  Not finding anything else "wrong", I finally replaced the sensor and have not had any trouble with cold weather running since.

If you can test the resistance you can tell if yours is "off by an order of magnitude" too.  PM me if you need more information as I don't have it handy at the moment.