K100RT fuel problem

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K100RT fuel problem

Postby gmitchell » Sat Jun 25, 2011 7:51 pm

i have a '85 K100RT ( 85,000 k's ). i have owned it for about 4 months and love it to bits. However two times recently it has let me down i think it is a fuel problem. i start it up and within a 100-200 mtrs or so it dies on me. the first time i think i had moved the electronic fuel control a bit when i was accessing the battery, played around a little bit and got it started (not sure what i did!). However this time i have unable to restart the old girl. can anyone suggest anything i can do or where i can take to get it repaired. i live south of the river (warnbro). any help would be appreciated.
regards graham
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Re: K100RT fuel problem

Postby astroengineer » Sun Jun 26, 2011 10:53 am

Hi Graham - welcome to the wonderful world of the old Ks (I've owned an 85 K100RS for ~5yrs) ! This could be pretty simple - seems like most of the old ones have need of attention to the electronics connectors - I've found that mine likes an annual "pat on the head" (unplug & refit the main connectors) in the fuel & ignition control circuits, although since I coated the contacts with some silicon tune-up grease it has been good for a long time (so now it will die on me this week!).
First check whether the fuel pump is running, though - you should hear it for a few seconds when you hit the starter button - if its running you probably have fuel pressure, so next thing is the controller connector. If not, first pull the left knee pad off & make sure the connector is ok beneath the front/left side of the tank (it pulls off downward) - care required as the fuel vapors tend to harden the insulation on the wire & connector plastic, it can crack & break (bad). I had to replace the connector on my K due to the connector body cracking - the contacts had gotten corroded & overheated. (Not a big deal if you can find the connector & have the tools though). More trouble is if it is running but the filter is clogged - but leave that for now.

The controller connector is basically just unplugging & carefully cleaning the fuel controller connector (the one above the battery you bumped) - there is a catch on the right end released through a hole inside the little tool tray, push it away from the connector with a small screwdriver and pivot the connector out from the right end where the cable comes into it). The contacts on both the cable & mating body are thin spring-fingers, so be careful not to snag them, but you can wipe them off with a cotton bud & some contact cleaner (or just flood it with cleaner if that sounds safer) - whatever you can get at Autopro (right, Dave?), Jaycar or supercheap will work fine. Also make sure that the cable is strapped in a way that doesn't pull on the connector when it goes back on.
If that doesn't help, more drastic surgery might be required, but try the easy stuff first.
Hope this helps...
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Re: K100RT fuel problem

Postby gmitchell » Mon Jun 27, 2011 9:34 am

many thanks for the help on this problem, i will give it a go. any thoughts of where i can take it to if i can't fix it?
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Re: K100RT fuel problem

Postby jono » Mon Jun 27, 2011 8:29 pm

I've heard the fuel pumps have a rubber component that fails with age and bits of rubber end up blocking the fuel delivery. the cheapest way to resolve this is to replace the fuel pump with of all things a Ford Falcon one.
If you cant resolve the problem I would recommend Dave Munro at Better Motorcycle Repairs, however Dave is off recovering from an operation and wont be back on deck till mid July.

Good Luck
JonO
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Re: K100RT fuel problem

Postby goldie » Mon Jun 27, 2011 9:50 pm

My k75 was doing the same thing.I also had an r1100 rt ,in both cases it turned out to be the hall sensor which is in the front of the motor it runs the ignition system. I hope it is a fuel problem because the hall sensors are dear.I would recomend talking to one of the BMW mechanics that are around.
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Re: K100RT fuel problem

Postby gmitchell » Wed Jun 29, 2011 1:03 pm

many thanks for your advice on the fuel problem, it turned to be a loose connection behind the fuel pump fuse. so fingers crossed off i go. but i've got the bike transporters phone no.in my phone tho'.
regards graham
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